International Union of Speleology
Informatics Commission - Dictionary Sub-commission

The UIS Cave and Karst Glossary
Stage 1

Terms published: 2023-04-14
Preamble updated: 2023-05-03

This is a works-in-progress Stage 1 of introducing the English version of the UIS Cave and Karst Glossary. At this stage of the project it is effectively just a direct conversion of Malcolm Field's 2002 Second Edition PDF US-EPA publication (A Lexicon of Cave and Karst Terminology with Special Reference to Environmental Karst Hydrology), but with our Term Numbers added. With Malcolm's assistance we are using it as the starting point for a major UIS Glossary resource. In April 2023 the UIS Caver's Multi-lingual Dictionary concepts were linked to this Glossary, at last providing it with definitions. Both of these resources now form part of the UIS Dictionary System. More details about the Glossary can be found on our Project page.

Each term can be directly accessed or linked to by appending for example, #33, to the address of this page in order to go directly to Term Number 33. These Term Numbers are now stable and are independent from the Concept Numbers used in the Multi-lingual Dictionary. Similarly, details of references can be accessed: e.g. for Reference [10], append #ref10 to the page address and press <Enter>. This web page can also be downloaded for offline use (675KB). Printing or producing a PDF of this web page will run to about 207 A4 pages, with intelligent page breaks.

The conversion from the 2700-term PDF Lexicon to this web page has involved quite a lot of detailed work, and there could be things we missed, so if you notice anything that needs fixing, please do email us with the details. Any temporary editorial comments added by the Glossary Project will show as [GP: .... ].

Terms Number	Terms	Definition / Description
1	abîme	(French) 1. An abyss. 2. A wide, deep shaft, in limestone, the walls of which are vertical or overhanging [10].
2	ablation	The wearing away of ice or snow through the process of evaporation [16].
3	abney level	Type of clinometer with a bubble tube used in cave survey to determine vertical angles [25].
4	abris sous roche	(French) See rock shelter.
5	abseil	1. (n.) A controlled descent of a rope using friction obtained by either wrapping the rope around the body in a particular way or passing the rope through a carabiner or passing the rope through a descender [25]. 2. (v.) To do an abseil [25]. Synonym: rappel.
6	absorption	The process by which substances in gaseous, liquid or solid form dissolve or mix with other substances [22].
7	abyss	Extremely great depth [16].
8	accelerated corrosion	A localized concentration of solution intensity, produced by factors favoring greater aggressivity of the water in certain parts of the karstland creating differential solution rates and thereby a marked unevenness in the overall erosion of the karstland [19]. See also corrosion; alluvial corrosion.
9	accessory mineral	Mineral constituents of a rock occurring in very small amounts [16].
10	accidental	An animal accidentally living in a cave [25].
11	acclivity	Ascending a slope [16].
12	accretion	Land addition by sediment deposition of a stream [16].
13	accumulation	Building of new land by addition of sedimentary deposits [16].
14	acetylene	An inflammable hydrocarbon gas, C₂H₂, produced by water reacting with calcium carbide. When burned, yields carbon dioxide as well as light [25].
15	acid	Any chemical compound containing hydrogen capable of being replaced by positive elements or radicals to form salts. In terms of dissociation theory, it is a compound which, on dissociation in solution, yields excess hydrogen ions. Acids lower the pH. Examples of acids or acidic substances are hydrochloric acid, tannic acid, and sodium acid pyrophosphate [6].
16	acidity	The property of water having a pH below 4.5 that is caused by the presence of mineral acids. Usually expressed in equivalent amounts of calcium carbonate [16]. See also alkalinity; pH.
17	acid mine drainage	Acid waters originating from surface or underground mine workings [16].
18	acoustic log	Geophysical borehole log measuring the speed of sound in rocks to determine porosity [16].
19	acoustic resistance	The product of wave velocity and rock density indicating the reflective power of a boundary between two strata [16].
20	activated charcoal, activated carbon	A granular material usually produced by the roasting of cellulose base substances, such as wood or coconut shells, in the absence of air. It has an extremely porous structure and is used in water conditioning as an adsorbent for organic matter and certain dissolved gases [6]. It is especially useful for adsorbing tracer dyes.
21	active cave	1. Cave containing a running stream. 2. Cave in which speleothems are growing. (Less common and less desirable usage.) Compare live cave [10].
22	active glacier	Glacier in the stage of actively enlarging and moving as a result of accumulation of precipitation that exceeds the rate of ablation.
23	active water	Water with corrosive properties [16].
24	adaptation	An inherited structural, functional, or behavioral characteristic that improves an organism’s chances for survival in a particular habitat [23]. See also mutation.
25	adiabatic	The property of thermodynamic process with no heat exchange [16].
26	adjusted stream	Stream flowing parallel to the strike of underlying beds [16].
27	adsorption	Adherence of gas molecules, ions, or molecules in solution to the surface of solids [22].
28	adsorption isotherm	A graphical representation of the relationship between the bulk activity of adsorbate and the amount adsorbed at constant temperature [22].
29	advection	1. The process whereby solutes are transported by the bulk mass of flowing fluid [6]. 2. Phenomenon of cool air mass intruding and interrupting evaporation and causing condensation due to heat loss [16]. See also convective transport.
30	aeolianite	See eolian calcarenite.
31	aeration	The process of bringing air into intimate contact with water, usually by bubbling air through the water to remove dissolved gases like carbon dioxide and hydrogen sulfide or to oxidize dissolved materials like iron compounds [6].
32	aeration, zone of	See zone of aeration.
33	aerial photograph	Photograph of the landscape taken from an airplane. Synonym air photo. See also stereo aerial photographs.
34	aerobic	A property of aquatic life forms that can exist only in the presence of oxygen. See also anaerobic.
35	age of caves	The ages of individual caves may vary enormously. In most regions the youngest cave passages have reached their present dimensions during the last 10,000 years, or since the last Pleistocene glacial retreat. In higher latitudes most caves can be related to erosion during the later Pleistocene climatic variations of the last million years, and older caves have largely been removed by continuing surface lowering. In tropical regions less interrupted erosion conditions have encouraged survival of older caves; the Mulu caves of Sarawak include large passages at least two million years old. Relict caves hundreds of millions of years old may survive in some buried limestones, but are commonly filled with younger sediments (see neptunian deposits), minerals or, very rarely, igneous rocks. These fill materials may themselves be dateable, either on the basis of contained fossil material (including pollen), by comparison with similar rock types that occur at the surface or by isotopic age determination methods identical to those applied to suitable surface rock materials. See also dating of cave sediments [9].
36	aggradation	Land addition through sediment deposition [16].
37	aggrading river	River that is actively elevating its bed by deposition of sediments [16].
38	aggregate	Grain mixture loosely held together [16].
39	aggregation	The formation of aggregates. In drilling fluids, aggregation results in the stacking of the clay platelets face to face; as a result, viscosity and gel strength decrease [6].
40	aggressive	Referring to water which is still capable of dissolving more limestone, other karst rock, or speleothems [25].
41	aggressive water	1. Water having the ability to dissolve rocks. In the context of limestone and dolomite, this term refers especially to water containing dissolved carbon dioxide to form carbonic acid or, rarely, other acids. 2. Quality of waters that attack metals and concrete chemically by dissolution [10].
42	aggressiveness	A measure of the relative capacity of water to dissolve rock material. In the context of karstification and speleogenesis this usually concerns the dissolution of limestone or dolomite by the action of dissolved carbon dioxide (carbonic acid), though other acids may also be involved [9].
43	aguada	(Spanish for watering place.) In Yucatán, shallow depression generally covering several hectares used for water supply [10].
44	A-horizon	The topmost eluviated horizon of a soil profile [16].
45	aîle	See aisle.
46	air pocket, air bell	1. An enclosed air space between the water surface and the roof of a cave [10]. 2. Part of a flooded passage where the ceiling rises above the water level to create an air pocket isolated from the rest of the cave [9].
47	air separating tank	A tank in which desorbed gases are separated from a liquid and evacuated by pumping [16].
48	air-space ratio	The ratio of (a) the volume of water that can be drained from a saturated soil or rock under the action of force of gravity to (b) the total volume of voids [22].
49	aisle	An elongated high narrow traversable passage in a cave [10]. See also crawl, crawlway; corridor; passage. Synonyms: (French) aisle, aîle; (German) Kluft; (Greek) farangothes ipoyios thiavasis; (Russian) hod; (Spanish) laminador vertical; (Turkish) dar geçit; (Yugoslavian) nis a.
50	albedo	The ratio of reflected radiation to total radiation on a natural surface [16].
51	algal limestone	Type of limestone formed by calcium secreting algae [16].
52	alkali flat	A salt covered or heavily saline depression in an arid environment [16].
53	alkaline	Any of various soluble mineral salts found in natural water and arid soils having a pH greater than 7. In water analysis, it represents the carbonates, bicarbonates, hydroxides, and occasionally the borates, silicates, and phosphates in the water [6].
54	alkalinity	The property of water to neutralize acids. Usually expressed in terms of calcium carbonate equivalents [16]. See also acidity; pH.
55	allochthonous	Said of material originating from a different locality than the one in which it has been deposited [16]. See also autochthonous.
56	allochthonous drainage	Less common synonym for allogenic drainage [9].
57	allogene stream	A surface-water course flowing over a karst terrane, but fed by a spring (or springs) issuing from a non-karst terrane [20]. Synonyms: (French) rivière allogène (cours d’eau); (German) allochthoner Fluss (all. Waßerlauf); (Greek) allothigenes ryax, or potamos; (Italian) corso d’acqua allogeno; (Spanish) río alóctono; (Turkish) karst disi kökenli akarsu; (Yugoslavian) alogena rijeka, alogena reka.
58	allogenic	Formed or generated elsewhere, usually at a distant place [1]. See also autogenic; recharge, allogenic; recharge, autogenic.
59	allogenic drainage	Underground karst drainage that is derived entirely from surface run-off that originates on adjacent non-karstic, generally impermeable, rocks. Also allochthonous drainage. See also autogenic drainage [9].
60	allogenic valley	A karst valley incised by a watercourse originating on impervious rock with a volume sufficient for it to traverse a limestone area on the surface. The valley is incised from the limestone contact and with the passage of time the river is increasingly likely to pass underground as the waters enlarge joints. Occasionally such a valley may represent the large- scale collapse of the cavern system along a subterranean stream or the enlarging of a series of karst windows [19].
61	alluvial	Pertaining to or composed of alluvium or deposited by a stream or running water [6]. Also applies to material lining the floor of a cave and deposits at the mouth of a spring.
62	alluvial apron	A fan-like plain from the deposition of glacial outwash [16].
63	alluvial channel	River or stream channel bed composed of unconsolidated alluvial material [16].
64	alluvial corrosion	Greater intensity of solution, caused by the passage of water through unconsolidated deposits rich in carbon dioxide, thus increasing aggressivity [19]. See also corrosion, accelerated corrosion.
65	alluvial fan	A fan-like deposit of detrital material from steep mountain slopes [16].
66	alluvial plain	A plain formed by the deposition of water borne sediments [16].
67	alluvial veneer	A very thin cover of water borne sediments [16].
68	alluvium	A general term for clay, silt, sand, gravel, or similar unconsolidated material deposited during comparatively recent geologic time by a stream or other body of running water as a sorted or semi-sorted sediment in the bed of the stream or on its floodplain or delta or as a cone or fan at the base of a mountain slope [6].
69	alpine karst	1. Karst formed at high latitude, or in polar regions regardless of altitude. 2. Almost synonymous with glaciokarst but restricted to areas of high altitude and relief [9]. Synonyms: glaciokarst; nival karst.
70	alternative	Adjective used to designate an intake or resurgence operating only during rainy seasons; in some areas reversible; equivalent to intermittent. Also used as a noun [10].
71	alveolar	1. Consisting of a honeycomb shape [16]. 2. A specific erosional pattern resulting in a cellular structure [16]. See also alveolization.
72	alveolization	(From the Latin word “alveolatus”, meaning hollowed out.) Pitting of a rock surface produced by wind loaded with sand, by water charged with carbonic acid, or by plant roots [10]. See also alveolar. Synonyms: (French) alvéolisation; (German) Aeolisation ? Wabenverwitterung; (Greek) kypselothis epiphania; (Italian) alveolizzazione; (Spanish) alveolizacion; (Turkish) çukurlaşma; (Yugoslavian) alveolizacija.
73	ammeter	A meter used to measure the flow of water in a stream channel. Synonym: current meter [16].
74	amorphous silica	Silica with no definite crystalline structure [16].
75	analysis, chemical	Laboratory procedure in water quality determination to identify chemical constituents [16].
76	analysis, complete chemical analysis	Chemical analysis of a water sample for physical, chemical, and bacteriological constituents [16].
77	analysis, core	Petrophysical analysis of a rock core acquired through the process of boring a hole in rock with the intention of producing a core of rock as opposed to chips [16].
78	analysis, morphometric	A geodetic and geometric description of basin, stream network, or sinkhole plain, the purpose of which is to determine the frequency and hierarchy of occurrences [16].
79	analysis, sieve	Mechanical grain size analysis by sieving an unconsolidated material through a series of sieves [16].
80	anastomosis	1. The development of a network of branching, intersecting, and rejoining channels in a two dimensional system. Anastomosing tubes, or cave anastomoses, which are generally formed due to dissolution by slow, poorly directed, phreatic flow along a bedding-plane parting or fracture in limestone, represent an important element in the early stages of cave development. Individual anastomoses most commonly have a diameter of approximately 100 mm and networks may contain hundreds of tubes. Most anastomoses are abandoned when one channel offers preferential flow conditions so that it increases in size at the expense of others. Such abandoned or relict anastomoses are commonly only exposed by subsequent wall or roof collapse [32]. 2. A network of tubular passages or holes in a cave or in a cave or solution-sculptured rock. A complex of many irregular and repeatedly connected passages[9, 21]. Synonym: labyrinth; (French) anastomose; (German) Labyrinth; (Greek) anastomosis; (Italian) anastomosi; (Russian) labirint; (Spanish) anastomosís; (Turkish) geçit şebekesi; (Yugoslavian) splet kanala.
81	anastomotic cave pattern	A type of maze cave consisting of tubular passages or holes in a cave or in a solution-sculptured rock. A complex of many irregular and repeatedly connected passages. Synonym: labyrinth.
82	anchor	A fixed object used to secure a man whilst operating a safety rope or for attaching equipment such as ladders or ropes [25].
83	anchor ice, ground ice	Ice that is temporarily attached to the bottom of a river [16].
84	anemolite	A helictite in which the eccentricity is ascribed to the action of air currents [10]. The word is derived from wind-control theory of helictite formation [9].
85	anemometer	A device used to measure wind speeds [16].
86	angle of contact, wetting angle	The angle between the liquid phase and solid boundary measured through the liquid phase [16].
87	angle of repose	The natural slope of unsupported granular material [16].
88	anglesite	A cave mineral — PbSO₄ [11].
89	angular	The property of unconsolidated grains with sharp edges [16].
90	angular unconformity	A geological unconformity with marked difference in dip of the superimposed series [16].
91	anhydride	Anhydrous calcium sulfate, CaSO₄ [16].
92	anion	A negatively charged ion that migrates to an anode, as in electrolysis [6].
93	anion exchange	Ion exchange process in which anions in solution are exchanged for other anions from an ion exchanger [6].
94	anisotropic	The property of aquifer systems displaying different hydrological properties in different directions [16]. See also anisotropy; anisotropic mass.
95	anisotropic mass	A mass having different properties in different directions at any given point [22].
96	anisotropic steering	Anisotropic structures (anisotropies) in the rock like schistosity, inclusions and fractures which can deviate or “steer” the direction of fractures subsequently developed.
97	anisotropy	The condition of having different properties in different directions [22].
98	annual frost zone	The top layer of ground subject to annual freezing and thawing [16].
99	annual mean	The mean value taken over all events that have occurred during a year such as precipitation, river stages, water-table levels [16].
100	annulus	The annular space between drill pipe and casing or between casing and the borehole wall [16].
101	anomaly	The deviation from normally expected findings, especially in exploration geophysics indicating a change in subsurface environmental conditions [16].
102	antecedent precipitation index	A precipitation index that is based on the amount of previous precipitations [16].
103	antecedent-soil moisture	The degree of water saturation in the soil prior to a precipitation event [16].
104	antecedent stream	A stream having established its course before occurrence of orogenic events that would later alter the general drainage pattern [16].
105	antenna (plural antennae)	A feeler; an appendage, sensory in function, that occurs in pairs on the heads of crustaceans, insects, and certain other animals [23].
106	anthodite	1. Radiating crystals of aragonite, mostly sharp needles 1–20 mm long. They occur sporadically in some caves but they may also be spectacularly abundant, with clean white crystals growing all over the rock and calcite surfaces. Carlsbad Caverns (USA) and Grotte de Moulis (France) have fine anthodite displays [9]. 2. A cave formation composed of feathery or radiating masses of long needlelike crystals of gypsum or aragonite, which radiate outward from a common base [10]. See also cave flower.
107	anthropocentric definitions	Definitions of caves or parts of caves that include accessibility by human explorers as one of their limiting conditions. Most well known among these is the definition published by the International Speleological Union, that “A cave is a natural underground opening in rock that is large enough for human entry” (see proto-caves) [9].
108	anticlinal valley	A valley that is established along the axis of an eroded anticline [16].
109	anticline	Upfolded stratum [16].
110	aphthitalite	A cave mineral — (K,Na)₃Na(SO₄)₂ [11].
111	apparent ground-water velocity	See specific discharge.
112	appendage	An arm or other limb that branches from an animal’s body [23].
113	approach segment	That part of a hydrograph curve before onset of precipitation [16]. See also hydrograph.
114	apron	A smooth bulging mass of flowstone covering sloping projections from walls of caves or limestone cliffs [10].
115	aquatic	Living in water. Aquatic cave animals include amphipods, isopods, crayfish, planarians, fish, and blind salamanders [23]. See also terrestrial; marine.
116	aqueduct	A conduit to convey water, usually above ground [16].
117	aquiclude	A formation which, although porous and capable of storing water, does not transmit it at rates sufficient to furnish an appreciable supply for a well or spring. See also confining unit [22].
118	aquifer	1. A formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs [6]. 2. A ground-water reservoir. 3. Pervious rock that is completely saturated and will yield water to a well or spring. Historically the term has been applied to beds favoring early cave development, probably synonymous with some inception horizons [18].
119	aquifer, artesian	A confined aquifer where the potentiometric surface rises above the top of the aquifer bed [16].
120	aquifer, coastal	An aquifer in a coastal region open to salt-water intrusions [16].
121	aquifer, flowing artesian	An artesian aquifer in which the water, under hydrostatic pressure rises above the land surface.
122	aquifer, karst	An aquifer in which the flow of water is or can be appreciable through one or more of the following: joints, faults, bedding-plane partings, and cavities — any or all of which have been enlarged by dissolution [18].
123	aquifer, leaky	An aquifer overlain or underlain by semipermeable strata from or into which water will flow [16].
124	aquifer stimulation	A type of development that is done in semiconsolidated and completely consolidated formations to alter the formation physically to improve its hydraulic properties [6].
125	aquifer storage	Gas storage in an aquifer [16].
126	aquifer system	A body of permeable and poorly permeable material that functions regionally as a water-yielding unit; it comprises two or more permeable beds separated at least locally by confining beds that impede ground-water movement but do not greatly affect the regional hydraulic continuity of the system; includes both saturated and unsaturated parts of permeable material [22].
127	aquifer test	A test to determine hydrologic properties of the aquifer involving the withdrawal of measured quantities of water from or addition of water to a well and the measurement of resulting changes in head in the aquifer both during and after the period of discharge or additions [6].
128	aquifere epikarstique	See epikarst zone.
129	aquifuge	A formation which has no interconnected openings or interstices and therefore neither stores nor transmits water [22]. See also confining unit.
130	aquitard	A confining bed that retards but does not prevent the flow of water to or from an adjacent aquifer; a leaky confining bed. It does not readily yield water to wells or springs, but may serve as a storage unit for ground water [22]. See also confining unit.
131	aragonite	1. A relatively rare form of calcium carbonate (CaCO₃), chemically identical to the more common calcite but of orthorhombic crystal form. Its pure form is metastable in the cave environment, where calcite forms preferentially. It is relatively abundant in some caves due to the presence of impurities, notably strontium, that distort the carbonate lattice and favor aragonite growth. The commonest form seen in caves as small radiating crystals (anthodites) that develop in humid caves, where surfaces are covered by a moisture film but not by flowing water. 2. A mineral composed of calcium carbonate, CaCO₃, like calcite but differing in crystal form [10]. 3. An unstable orthorhombic carbonate mineral, CaCO₃ [16].
132	ardealite	A cave mineral — Ca₂(SO₄)(HPO₄)·4H₂O [11].
133	area of influence of a well	The area surrounding a pumping or recharging well within which the potentiometric surface has been changed [22].
134	arête and pinnacle karst	A landscape of naked reticulated raw-topped ridges having almost vertical slopes and a relief of as much as 120 meters. The ridges rise above forest- covered corridors and depressions. Found in New Guinea at elevations of 2,000 meters and more [10]. Both pinnacle karst and arête karst are varieties of limestone landscape formed under equatorial rain forest cover. They are characterized by vertical sided blades of bare rock fretted by dissolution [9].
135	argillaceous	The property of rocks containing clay in non-negligible proportions [16].
136	argillaceous limestone	Limestone containing considerable amounts of clay [16].
137	arid	The property of dry climates and regions with a net deficiency of moisture [16].
138	arrival time	1. The time of arrival in subsurface flow tracing for the first tracer pulse to arrive at a discharge location. 2. The time of arrival in geophysics for the first seismic wave to arrive at a geophone [16].
139	artefact	A product of human manufacture or art, e.g. tools of bone, stone, etc., paintings, engravings. In caves, tools are often buried in sediment. (Scientific attention should be drawn to the finding of artefacts in caves [25].)
140	artesian	Synonymous with confined.
141	artesian aquifer	Synonymous with confined aquifer. See aquifer, artesian.
142	artesian flow	Flow through a confined aquifer where the elevation of the overlying aquiclude is locally depressed so that the entire aquifer is saturated and the flow is under hydrostatic pressure. Some maze cave development in cavernous limestones may be due to artesian flow, which is commonly related to synclinal fold structures [9].
143	artesian spring	See spring, artesian.
144	artesian well	A well deriving its water from a confined aquifer in which the water level stands above the ground surface [6]. Synonym: flowing artesian well.
145	arthropods	Animals with jointed legs and bard external skeletons (exoskeletons). The group includes insects, crustaceans, spiders, millipedes, and several other types of animals commonly found in caves [23].
146	artificial discharge	The discharge of ground water by pumping wells [16].
147	artificial recharge	Recharge at a rate greater than natural, resulting from deliberate or incidental human activities [6].
148	ascender	A mechanical device used by cavers who are either ascending or are descending through a vertical opening in a cave (e.g. vadose shaft) that uses a cam to grip a rope while downward pressure is being applied to the device [13]. See also mechanical ascender; prusiking; prusik knot.
149	association	A relatively stable community of different species living in a characteristic habitat [25].
150	atmometer	An instrument used to measure evaporation intensities [16].
151	atmosphere	A gaseous envelope of the earth that contains and transports air and water in vapor and condensed form [16].
152	attapulgite clay	A colloidal, viscosity-building clay consisting of hydrous magnesium aluminum silicates and used principally in salt-water drilling fluids [6].
153	attrition	The wearing away of rocks by friction [16].
154	auger	A rotary drilling device where the dry cuttings are removed continuously by helical grooves on the drill pipe [16].
155	aurichalcite	A cave mineral — (Zn,Cu)₅(CO₃)₂(OH)₆.
156	autochthonous	Property pertaining to sedimentary material originating and deposited at about the same location [16]. See also allochthonous.
157	autochthonous drainage	Less common synonym for autogenic drainage [9].
158	autogenic, authigenic	Formed or generated in place [1]. See also allogenic; recharge, autogenic; recharge, allogenic.
159	autogenic drainage	Underground karst drainage that is derived entirely by absorption of meteoric water into the karst rock surface [9]. Synonym: autochthonous drainage. See also allogenic drainage.
160	available water	The water available to plants in the soil zone as defined by the interval between field capacity and wilting point [16].
161	aven	1. A hole in the roof of a cave passage that may be either a rather large blind roof pocket or a tributary inlet shaft into the cave system. A feature described as an aven when seen from below may equally be described as shaft when seen from above, and the naming of such a feature commonly depends purely upon the direction of exploration. Many avens close upwards to impenetrable fissures but may still be important hydrological routes; few caves are without them. In parts of France, aven is equivalent to the British term, pothole [9]. 2. (French) A vertical or highly inclined shaft in limestone, extending upward from a cave passage, generally to the surface; smaller than an abîme. Commonly related to enlarged vertical joints. Compare cenote; natural well; pothole. 3. (British) A vertical extension from a shaft in a passage or chamber roof that tapers upward rather like a very elongate cone [10]. Compare dome pit.
162	average interstitial velocity	See velocity, average interstitial.
163	azimuth	The true bearing of a survey line, determined by measurement from an accurate survey or by observations of sun or stars [25].
164	azonal soil	Soils without distinct layering in horizons [16].
165	azurite	A cave mineral — Cu(CO₃)₂(OH)₂ [11].
166	backflooding	1. Temporarily rising water level in a cave caused by downstream passage being too small to pass an abnormally high discharge. The excavation and reexcavation of some caves is ascribed to the enlargement of a passage at or near the water table by gravity flow alternating with periods of calcite precipitation [10]. 2. Flooding due to backup of excess flow behind a constriction in a major conduit. Water that is ponded in tributary passages and proto-caves upstream of the constriction may contribute to the enlargement of maze caves [9].
167	background noise	The level of intensity of signals due to normal activities other than the specific signal emission [16].
168	backwater	The accumulated water above the normal level of a water course due to impoundment at a point downstream [16].
169	backwater curve	Water surface profile in a stream or channel above a constriction or impoundment [16].
170	bacon	Thin, elongated, translucent flowstone having parallel colored bands on or projecting from roofs and walls of some caves [10]. See also blanket; curtain; drapery.
171	bacteria	Simple, colorless one-cell plants, most of which are unable to manufacture their own food using sunlight. Bacteria are possibly important in caves as synthesizers of food materials from minerals. They are also important as decomposers [23].
172	bactericide	A substance used to destroy bacteria (e.g. iron bacteria) [6].
173	bailer	1. A cylindrical container used to withdraw a sample of water from a well. 2. A cylindrical container with a bottom valve for the clearing of drill cuttings from the bottom of a borehole [16].
174	bailing line	Cable operating a bailer [16]. Synonym: sand line.
175	balcony	Any projection on the wall of a cave large enough to support one or more persons [10].
176	bank	Ascending slope bordering a river [16].
177	bank erosion	Erosion of a river bank [16].
178	bank storage	1. Subsurface conduit water that has been driven back up into older, higher karst levels and into the surrounding rock matrix during a high flow period. 2. River water that has infiltrated river banks during a high flow period and being retained in temporary storage [16].
179	barbels	Fleshy threadlike sensory structures hanging like whiskers near the mouths of certain fish, such as catfish [23].
180	bare karst	A type of karst landscape lacking soil cover and where dissolution of carbonate rocks to form karst landforms occurs primarily on the exposed bedrock surface [9]. See naked karst.
181	barite	1. A cave mineral — BaSO₄. 2. A natural finely ground barium sulfate used for increasing the density of drilling fluids [6].
182	barograph	A pressure recorder [16].
183	barometer	An indicator of barometric pressure [16].
184	barometric efficiency	The ratio of water level change to atmospheric pressure change in a well [16].
185	barrier	A geological formation or part of a formation having become impervious to ground-water flow due to a facies change [16].
186	barrier, freshwater	Barrier of freshwater injected into an aquifer to stop the inflow of seawater into a coastal aquifer [16].
187	barrier, hydrologic	Lithologic formation preventing horizontal movement of ground water [16].
188	barrier, permeability	A geologic or petrographic feature in a bed obstructing free flow [16].
189	barrier spring	See spring, barrier.
190	base exchange	The displacement of a cation bound to a site on the surface of a solid, as in silica- alumina clay-mineral packets, by a cation solution [6].
191	base flow	1. That part of the stream discharge that is not attributable to direct runoff from precipitation or melting snow; it is usually sustained by ground-water discharge [22]. 2. Sustained fair weather runoff [16].
192	base level	Lowest level of erosion by a stream [16].
193	base level of erosion	The lowest theoretical level of surface to be achieved by erosion [16].
194	base level, karst	See karst base level.
195	base line	1. An arbitrary line from which deflections of self potential are read [16]. 2. Shale line [16].
196	baseline monitoring	The establishment and operation of a designed surveillance system for continuous or periodic measurements and recording of existing and changing conditions that will be compared with future observations [22].
197	base of karstification	Level below which karstification has not occurred. See also karst base level.
198	base width	The width of the hydrograph as determined by a line parallel to the time axis cutting through the points where the rising limb starts and where the recession curve ends [16].
199	basin	Hydrogeographic unit receiving precipitation and discharging runoff in one point [16].
200	basin characteristics	The physiographic, geologic, and ecologic characteristics of a basin [16].
201	basin, closed	Drainage basin with no surface flow outlet [16].
202	basin, drainage	The area contributing to runoff which sustains streamflow [16]. See also drainage basin.
203	basin, experimental	A basin chosen for the thorough study of hydrological phenomena [16].
204	basin, ground-water	The area throughout which ground water drains towards the same point. It can be larger than the associated drainage basin if permeable layers extend outside of the topographical divide [16]. In karst terranes, the ground-water basin often does not resemble the drainage basin.
205	basin, infiltration	Basin in which water is spread for recharge [16].
206	basin, intermontane	A basin lying between two mountain ranges [16].
207	basin method	A recharge method in which water is spread in shallow basins [16].
208	basin mouth	The point at which runoff leaves a basin [16].
209	basin perimeter	The circumference of a basin following the divide [16].
210	basin relief, maximum	The elevation difference between basin mouth and the highest point within a basin perimeter [16].
211	basin, settling	A basin used for the settling out of solids from suspension [16].
212	bat	A member of the order Chiroptera, the only mammals capable of true flight as they have membranes between the toes of their forefeet [25].
213	bathybenthic	Of the bottom of the truly deep areas of the sea, where the “rain” of organic material produces a deposit of food [23].
214	bathypelagic	Of the deep sea. Refers to the depths between roughly 3000 feet below the surface and the bottom of the sea. No food accumulates in these waters [23].
215	bathyphreatic	Referring to water moving with some speed through downward looping passages in the phreatic zone [25]. See bathyphreatic zone, ground water, phreas.
216	bathyphreatic zone	See bathyphreatic, ground water, phreas.
217	bathometer	An instrument for measuring water depths in wells [16].
218	beach	A shore consisting of sand or gravel deposits [16].
219	beachrock	1. Rock composed of sand grains and/or sand-sized shell fragments cemented by calcium carbonate, commonly formed very rapidly on some beaches in tropical and sub-tropical areas. Beachrock generally occurs as thin beds between bedding planes that dip seawards at angles similar to those of the beach slope [9]. 2. A friable to indurated rock consisting of sand grains of various minerals cemented by calcium carbonate; occurs in thin beds dipping seaward at less than 15°. Also known as beach sandstone [10].
220	bearing	The angle measured clockwise that a line makes with the north line. True, magnetic and grid bearings are measured respectively from true, magnetic and grid north [25].
221	bed	1. A layer in sedimentary rocks; a stratum [10]. 2. A sedimentary deposit of relatively small thickness and great areal extent, separated by bedding planes from over- and underlying deposits [16].
222	bed load	See bedload.
223	bed, lower confining	An impermeable bed underlying an aquifer [16].
224	bed, marker	Bed with characteristic features that can be followed over large areas for identification purposes [16].
225	bed, mortar	Secondary calcium carbonate cementations in the lower part of a soil profile [16]. Synonym: hardpan.
226	bed, river	The channel of a river covered by water [16].
227	bed roughness	The roughness of a channel or river bed [16].
228	bed, stream	The bottom of a stream covered by water [16].
229	bed, upper confining	Impermeable bed overlying an aquifer [16].
230	bedding	Applies to rocks resulting from consolidation of sediments and exhibiting surfaces of separation (bedding planes) between layers of the same or different materials (e.g., shale, sandstone, limestone, etc.).
231	bedding cave	See bedding-plane cave.
232	bedding grike	Term used to describe the occurrence of the dissolution and widening (similar to that which occurs in joints) of nearly vertical bedding in karst terranes [8]. Synonym: (German) Schichtfugenkarren.
233	bedding joint	A joint in rocks that runs parallel to or on a bedding plane [16].
234	bedding plane	1. A primary depositional lamination in sedimentary rocks that may be preserved, though possibly with different properties, in metamorphic rocks. These laminations may be clearly visible where lithologies change or where depositional cycles were completed/initiated, or they may be effectively invisible to the naked eye, marking subtle changes in depositional conditions. Most bedding planes were originally horizontal or very slightly inclined, but more steeply inclined bedding planes developed in rocks deposited in deltaic or sand dune environments or in marine reefs. When rocks are folded the bedding planes provide an indication of the degree of deformation. Bedding planes play a crucial role in the inception and ongoing development of most caves and many surface karst features [3]. 2. A plane that separates two strata of differing characteristics [10]. See also parting.
235	bedding-plane cave	1. Bedding planes are widespread and very significant features within most carbonate rocks, and cave passages are commonly guided by them. Their structure, their distribution and the chemical contrasts that some bedding planes provide may be the major influence during the earliest phases of development of a cave system. The term bedding-plane cave is strictly applied to a passage that has not enlarged by growth into a major tube or canyon, but has remained almost entirely on the bedding plane. A famous example is Hensler’s Passage, in Gaping Gill, Yorkshire, which is over 400 m long, nearly over 5 m wide and nowhere higher than 1 m [9]. 2. A passage formed along a bedding plane, especially when there is a difference in susceptibility to corrosion in the two beds [10]. 3. A cave whose location is controlled by the bedding of the enclosing formation or formations [20]. Synonyms: (French) grotte de stratification; (German) schichtgebundene Höhle; (Greek) strosigenes speleon; (Italian) grotta di interstrato; (Russian) pescera v ploakosti naplastovanija; (Spanish) cueva adaptada a planos de estratificación; (Turkish) tabakalanma magarası; (Yugoslavian) slojna pećina.
236	bedding-plane parting	See bedding plane and parting.
237	bedeckter karst	See covered karst.
238	bedload	The part of the total stream load that is moved on or immediately above the stream bed, such as the larger or heavier particles (boulders, pebbles, gravel) transported by traction or saltation along the bottom; the part of the load that is not continuously in suspension or solution [6].
239	bedrock	Solid rock underlying unconsolidated material [16].
240	bench mark	A relatively permanent mark, natural or artificial, furnishing a survey point at a known elevation in relation to an adopted datum [16]. Bench marks, or marked points, connected by precise leveling, constitute the control of land-surface settlement in subsidence studies [21].
241	bend	Curve in a water course [16].
242	bentonite	A colloidal clay, largely made up of the mineral sodium montmorillonite, a hydrated aluminum silicate [6].
243	B-horizon	Illuvial horizon in which soluble material from the overlying A-horizon has been deposited [16].
244	belay	A safety rope tied around a caver that is played out or taken in by a second person as the caver moves. The purpose of the belay is to prevent the caver from falling more than a few feet [13].
245	beudantite	A cave mineral — PbFe₃(AsO₄)(SO₄)(OH)₆ [11].
246	bicarbonate	A salt containing the radical HCO₃⁻, such as Ca(HCO₃)₂ [10].
247	bifurcation	The forklike separation of a water course into two arms [16].
248	bifurcation ratio	The ratio of the number of stream segments of a given order to the number of segments of next higher order [16].
249	biological clock	An inherited time-measuring process within a living thing, which governs its responses to certain external events [23].
250	biomass	The total weight of living matter, whether in an entire community, at a particular trophic level, or of a particular kind of organism in the community. Thus we may refer to the biomass of a pond community, of herbivores in the pond, or of copepods in the pond [23].
251	biomicrite	A microscopic-textured limestone composed of skeletal grains in a matrix of micrite; micrite is a finely crystalline carbonate sediment with the upper crystalline diameter being 4 microns [20]. Synonyms: (French) biomicrite; (German) Biomicrite; (Greek) micrite; (Italian) biomicrite; (Spanish) biomicrita; (Turkish) biyomikrit; (Yugoslavian) biomikrit. See also micrite; peloid.
252	biospeleology	1. The study of subterranean living organisms, particularly in karst caves and other openings in rock formations[9, 21]. 2. The scientific study of cave animal life, or the biology of caves, karst, and groundwater. A biologist who specializes in this study is called a biospeleologist [23]. Synonyms: (French) biospéléologie, biospéologie; (German) Biospeläologie; (Greek) biospeleology; (Italian) biospeleogia; (Russian) biospeleologija; (Spanish) biospeleología; (Turkish) biyospeleoloji, magara canlıları bilimi; (Yugoslavian) biospeleologija.
253	biphosphammite	A cave mineral — NH₄H₂PO₄ [11].
254	birnessite	A cave mineral — (Na,Ca)Mn₇O₁₄·3H₂O [11].
255	blade	In a cave, a thin sharp projection jutting out from roof, wall, or floor, of which it is an integral part; generally the remains of a partition or bridge [10].
256	blanket	A thick layer of dripstone, not translucent [10]. See also bacon; curtain; drapery.
257	blind chimney	See chimney.
258	blind shaft	A vertical extension upwards from part of a cave, but not reaching the surface; small in area in relation to its height [25].
259	blind valley	1. A karst valley abruptly terminated by the passage underground of the watercourse which has hitherto resisted the karst processes and remained at the surface. An intermediate type, the half-blind valley, exists in which the valley form continues downstream from the sinkhole used under conditions of normal river flow. The watercourse only flows here intermittently and the valley may (except for its use as a flood conduit) be fossil in that it represents the section abandoned by the river as it sought progressively higher swallow holes [19]. 2. A karst valley with no evident downstream continuation, and one in which the water drains and disappears underground into one or more ponors [20]. 3. A valley that terminates abruptly at a point where its stream sinks, or once sank, underground. As sinks develop higher up the blind valley, the original valley termination may be dry under most flow conditions [9]. Related to marginal polje. Synonyms: (French) vallée aveugle; (German) Blindtal, (Kesseltal); (Greek) kliste karstike kilas; (Italian) valle cieca, valle chiusa; (Russian) slepaja dolina; (Spanish) valle ciego; (Turkish) kör vadi; (Yugoslavian) slijepa dolina, sepa dolina. See also half-blind valley; marginal polje.
260	bloedite	A cave mineral — Na₂Mg(SO₄)₂·4H₂) [11].
261	blowhole	1. Opening in the roof of a cave or cavern through which air is expelled vigorously. In coastal areas the phenomenon is usually due to compression of air within the cave by incoming tides or waves [20]. 2. Cliff top entrance to a sea cave, also known as a geo, gloop, or gloup [9]. 3. (Australian) A small hole in the surface of the Nullarbor Plain through which air blows in and out with observable force, sometimes audibly [10]. Related to breathing hole. Synonyms: (French) trou souffleur; (German) Windhöhle; (Greek) ope ekphysosa; (Italian) bocca soffiante; (Spanish) soplador; (Turkish) üflenme agzı; (Yugoslavian) vjetrenica, veternica, puhaljka, pihalnik, dihalnik. See also steam hole.
262	blowing cave	A cave out of which or into which a current of air flows intermittently [10].
263	blowing well	A well or borehole into which air is sucked and from which air is blown (often with considerable velocity) due to changes in barometric pressure or in water level. The phenomenon indicates that the well or borehole is in communication with an underground air-filled cavity. Synonyms: (French) puits souffleur; (German) Windkamin; (Greek) ekphysosa ope; (Italian) pozzo soffiante; (Russian) dujuścij kolokec; (Spanish) sondeo soplador; (Turkish) üfleç kuyu. See also steam hole.
264	blowout	An uncontrolled escape of drilling fluid, gas, oil, or water from a well caused by the formation pressure being greater than the hydrostatic head of the fluid in the hole [6].
265	blue hole	1. Deep resurgence pool, notably in Jamaica and Florida, that may have a blue color due to the presence of algae. Also a deep submarine cave of the Bahamas. The latter type are large flooded shafts cut into the limestones of the shallow reefs and lagoon floors. Many are 100 m in diameter and some are 100 m deep. Opening from the shafts are flooded cave passages at various depths, some of which have been explored subhorizontally for more than 1 km. Their origins are complex. Extensive stalagmite deposits show that large old caves were drained when sea-levels were low during the Pleistocene (when water was held in the ice sheets). They are now being modified by marine dissolution, notably at the interface between fresh and salt waters (sea littoral zone) and by powerful tidal flows between connected holes [9]. 2. (Jamaican) A major emergence where water (artesian spring) rises from below without great turbulence. 3. (Bahamas) A drowned solution sinkhole [10]. 4. Caribbean expression for a major quiet up- welling karst spring inland or along the coast. The blue color is due to the scattering of sunlight by water molecules, although in some cases it may be attributed to the presence of calcareous algae [20]. Synonyms: (French) source bleue (Jura), bleu-fon (South of France); (German) Blaue Grotto; (Greek) galapo speleo. See also boiling spring.
266	bobbin	A decender that opens to enclose the rope around two fixed pulleys. May have a handle (“STOP”) which must be squeezed to allow descent [25].
267	Bodenbedeckter karst	See subsoil karst.
268	bog	Swamp [16].
269	bogaz	1. (Slavic) An elongated depression in limestone or karst terrain; thus it embraces a defile, a blind valley or a ravine leading to a ponor. It can be considered as a giant grike. This meaning is based on the Serbian use [20]. 2. A variable-discharge artesian spring in which hydrostatic pressure is great enough to cause a turbulent or even fountain-like discharge. 3. A long narrow chasm enlarged by solution of the limestone [10]. 4. Large linear fissure or box valley through a karst block. Effectively a giant grike, perhaps 50 m deep and 1 km long, formed by dissolution on a fault or joint in very massive limestone [9]. Synonyms: (French) défilé, bogaz; (German) Doline, Karstgaße, Blindtal, Zangön; (Greek) faragothis doline; (Spanish) zanjón; (Turkish) bog az; (Yugoslavia) bogaz. See also canyon; gorge; grike; corridor; struga; zanjón.
270	boiling spring	See spring, boiling.
271	bollard	A projection of rock over which rope, tape or wire can be placed to create an anchor [25].
272	bolt	A high tensile steel bolt used as an anchor; either a conical bolt screwed into a metal holder in a hole drilled in rock, causing expansion for grip, or a bolt with partially filed thread hammered into a slightly smaller hole [25].
273	bone-breccia	1. Cave breccia including much bone [10]. 2. A breccia containing many bone fragments. (Scientific attention should be drawn to the finding of such in caves [25].)
274	bone cave	A cave recognized particularly for its contained deposits of animal bones. The bones may be the remains of animals that fell into the cave, as in the Joint Mitnor Cave, Devon, or in many other pitfall or fissure sites. Alternatively the bones may be of animals that originally lived in the cave — and these may include man, as at Niah Cave, Sarawak, or at Russell Cave, USA. A third, and most important, type of bone cave is the ancient animal den, into which scavengers such as hyaenas dragged the remains of many other animals, as for example at Kirkdale Cave in North Yorkshire [3].
275	borehole	1. Boring into unconsolidated and consolidated materials for the purpose of subsurface hydrogeological investigations. 2. Synonym for a well developed phreatic tube passage [9].
276	botryoid, botryoidal speleothem	1. Generally sub-spherical or globular calcium carbonate deposits ranging in size between tiny beads and masses up to 1 m across. Botryoidal describes a form resembling a bunch of grapes [9]. 2. A grape-like deposit of calcium carbonate generally found on walls of caves [10]. Synonyms: clusterite; grape formation. See coralloid speleothem.
277	bottom hole	The lowest part of a drilled hole where the drilling bit cuts into the rock [16].
278	bottomland	A lowland along an alluvial river plain [16].
279	boulder clay	See glacial till.
280	boundary spring	See spring, boundary.
281	bourne	(British) 1. A stream that appears in a normally dry valley, particularly on the Chalk outcrop in southern England, during wet conditions [9]. 2. Intermittent stream in a normally dry valley in chalk country [10].
282	boxwork	1. A three-dimensional network of thin sheets of mineral projecting from a cave wall. The boxwork is vein fillings etched from the cave wall by dissolution of the host limestone and consists mostly of calcite and quartz. It is not common, but spectacular displays occur in Ind Cave, South Dakota, USA [9]. 2. Network of thin blades of calcite or gypsum etched out in relief on the limestone walls and ceiling of a cave [10].
283	brackish water	Water containing from 1000 to 10,000 ppm of total dissolved solids [16].
284	braided stream	A stream that divides into or follows an interlacing or tangled network of several small branching and reuniting shallow channels separated from each other by branch islands or channel bars, resembling in plan the strands of a complex braid [6].
285	brake bar	A round bar approximately 2½ × ¾ inches that is placed on rappel racks or carabiners so that rope can be threaded through the rack or carabiners for rappelling [13].
286	branchwork cave pattern	1. A cave system that has been formed by the intersection of tubular or canyon-like conduits as tributaries in the down-flow direction. 2. A dendritic cave system of subterranean watercourses having many incoming branches and no visible outgoing ones [10].
287	breakdown	See cave breakdown.
288	breakthrough	A quantum jump in erosional activity that is associated with the transition from dominantly laminar to dominantly turbulent flow conditions [9]. See turbulent threshold.
289	breakthrough curve	1. A plot of relative concentration versus time, where relative concentration is defined as C/Co with C as the concentration at a point in the ground-water flow domain, and Co as the source concentration [22]. 2. A plot of tracer concentration, C, versus time, t, for a ground-water tracing study in karst conduit for the purpose of quantitatively determining how much tracer mass was recovered, mean time of travel, mean tracer flow velocity, and related hydraulic flow and geometric parameters. Synonyms: recovery curve; tracer-breakthrough curve; tracer-recovery curve.
290	breakthrough time	The time required to develop a conduit large enough (usually 5–10 mm in diameter) to support turbulent flow [9].
291	breathing cave	Air movement through a cave is described as breathing when it reverses more frequently than the seasonal reversal of a through-draught in a cave with higher and lower entrances. Slow breathing occurs in response to barometric pressure changes, when the volume of cave air is forced to change. It is notoriously strong in large caves of the Australian Nullarbor Plain. More rapid wind reversals or oscillations, as in Breathing Cave, Virginia, are a resonance phenomenon, similar to the effect produced by air passing over the neck of a bottle. In the cave environment the resonant frequency is relatively low and periodic air flow reversals occur, rather than the sound waves observed at the higher frequencies met in the bottle neck example [9].
292	breathing hole	Opening in the roof of a cave, cavern or other underground void through which air is sucked in and expelled in a rhythmic manner similar to inhalation and exhalation of breath [20]. Related to blow hole and steam hole. Synonyms: (French) trou souffleur; (German) Luftloch, (Greek) anapnéousa opí spiléou; (Spanish) respirador; (Turkish) esintili delik.
293	breccia	1. Angular fragments of rock, commonly, but not inevitably, cemented by finer-grained materials including silica, iron minerals, and calcite to form a new rock. Many fault planes are marked by zones of broken rock, either loose or re-cemented, forming a fault breccia [9]. 2. Rock composed of angular fragments [16].
294	bridge	1. May be a natural bridge of bedrock normally formed outside a cave entrance by partial collapse leaving an isolated roof segment, as in the famous examples of Rakov Škocjan, Slovenia. Rock bridges may also occur inside caves due either surrounding phreatic dissolution or collapse between superimposed passages. Another common type inside a cave is a span of false floor where sediment is washed from below, as at The Bridge in GB Cavern in the Mendip Hills [9]. 2. In a cave, a residual rock span across a passage [10]. 3. In water wells, an obstruction in the drill hole or annulus. A bridge is usually formed by caving of the wall of the well bore, by the intrusion of a large boulder, or by filter pack materials during well completion. Bridging can also occur in the formation during well development [16]. See also natural bridge.
295	bridging effect	The forming of arches in a packing of materials [16].
296	brine	Water containing more than 100,000 ppm of total dissolved solids [16].
297	brittle deformation	The sudden failure of a rock with complete loss of cohesion across a plane.
298	brochantite	A cave mineral — Cu₄(SO₄)(OH)₆ [11].
299	brushite	A cave mineral — CaHPO₄·2H₂O [11].
300	bubble gage	A stage recorder based on the principle of equating a gas pressure to water level [16].
301	bucket	A measuring reservoir in liquid gaging instruments [16].
302	buffered solution	A solution that resists changes in the pH value upon addition of acids or bases [16].
303	buildup	The vertical distance the water table or potentiometric surface is raised, or the increase of the pressure head due to the addition of water [22].
304	buried karst	Karst topography entirely buried by relatively younger post-rock or sediments and not part of the contemporary landscape [17]. Synonyms: fossil karst; (French) karst couvert, karst fossile, paleokarst; (German) bedeckter Karst, Urkarst; (Greek) kaymeno paleokarst; (Italian) carso sepolto; (Spanish) karst soterrado; (Turkish) gömülü karst; (Yugoslavian) pokriveni krs̃. See also covered karst; paleokarst; subsoil karst.
305	buried valley	An ancient valley buried by recent, often glacial deposits [16].
306	burst	1. Periods of heavy rainfall [16]. 2. An explosive breaking of brittle rock material (e.g., rock burst in a deep mine tunnel).
307	caballing	The mixing of two water masses to produce a blend that sinks because of it is denser than its original components. This occurs when two water masses have the same density but different temperatures and salinities.
308	cable ladder	A ladder used in vertical caving that is made of two parallel cables with metal rungs held in place on the cables with metal tubes crimped to the cables [13].
309	cable way	A cable stretched across a river from which a cable car is suspended to allow for stream discharge measurements [16].
310	caisson	A protective chamber for the excavation of water submerged unconsolidated sediments [16].
311	calanque	(French) 1. Cove or small bay. 2. A valley excavated in limestone or formed by collapse of the roof of a cave and subsequently submerged by a rise in sea level [10].
312	calc-	Prefix meaning limy; containing calcium carbonate [10].
313	calcarenite	1. Limestone or dolomite composed of coral or shell sand or of grains derived from the disintegration and erosion of older limestones. Size of particles ranges from 1/16 to 2 millimeters [10]. 2. A carbonate rock that consists predominantly (>50%) of sand-sized calcite (or dolomite) particles. Many of the particles are the angular or degraded fragments of fossil shells [9].
314	calcareous	1. Containing calcium carbonate [10]. 2. Descriptive of a rock that contains calcium carbonate [9].
315	calcareous tufa	See sinter.
316	calcification	Replacement of the original hard parts of an animal or plant by calcium carbonate [10].
317	calcilutite	1. Clastic limestone or dolomite in which the grains have an average diameter of less than 1/16 millimeter; calcareous mudstone [10]. 2. A carbonate rock that consists predominantly (>50%) of silt and/or clay size calcite (or dolomite) particles [9].
318	calcirudite	A fragmental limestone in which the particles are generally larger than 2 millimeters [10].
319	calcite	1. The commoner, more stable, mineral form of calcium carbonate, CaCO₃. It is the dominant component of all limestones and, due to its dissolution and reprecipitation by natural waters at normal temperatures, it is also the dominant mineral of chemical cave deposits including stalactites and stalagmites. It is white or colorless when pure but may be stained, most commonly to yellows and browns, by included impurities such as iron oxides. Its uninterrupted growth in a pool may allow development of good crystals, shaped as elongate scalenohedral pyramids of trigonal habit. Growth in stalactites and stalagmites is either in masses of fine parallel or radiating needles, or in a mosaic of larger rhombic crystals, easily identified by their well developed cleavage surfaces. Calcite is also the dominant vein mineral in limestones [9]. 2. A mineral composed of calcium carbonate (CaCO₃) like aragonite but differing in crystal form; the principal constituent of limestone and other speleothems [10].
320	calcite bubble	A hollow sphere formed by the deposition of calcite around a gas bubble; the interior is smooth, and the exterior consists of small jagged crystals [10].
321	calcite flottante	(French) See floe calcite.
322	calcite raft	A veneer of reprecipitated calcite forming a sheet over all or part of the surface of a static cave pool in conditions favoring the release of carbon dioxide [19].
323	calc-sinter	See sinter.
324	calcium carbonate	Naturally occurring compound with the chemical formula CaCO₃. It occurs commonly as the mineral calcite and less commonly as aragonite, and is the major component of carbonate rocks including limestone and marble. It also forms the matrix or cement that holds together many sandstones and other sedimentary rocks [9]. See also dolomite.
325	calcrete	(South African.) See caliche.
326	calibration	The experimental evaluation of the scale readings of an instrument against an absolute standard [16].
327	caliche	1. (Chilean and Peruvian.) A natural deposit of nitrates and other salts precipitated at the soil surface. 2. (Mexico and Southwestern United States.) Indurated calcium carbonate and other salts found in the soil at the surface in arid and semiarid regions, generally formed by evaporation of lime-bearing waters drawn to the surface by capillary action. 3. In some areas, refers to hardpan resulting from concentration of carbonate in the soil by downward leaching and reprecipitation [10]. 4. A deposit of precipitated minerals, mainly calcite or gypsum or both, formed in the soil or near-surface layers in arid and semi-arid zones at the horizon where ascendant capillary water evaporates and salts held in solution are deposited. 5. A similar deposit, formed by precipitation of salts leached from near-surface material and reprecipitated at shallow depths from downward moving waters [20]. Synonyms: (French) croûte; (German) Kalkkruste, Ca-Horizont; (Greek) apóthema oriktón aláton; (Italian) caliche; (Spanish) caliche; (Turkish) kaliçi. See also hardpan; havara; kafkalla; kankar; kunkar; nari; calcrete.
328	callow	(English) Top or rubble bed of a quarry.
329	canal seepage loss	Water lost to the subsurface by seepage through the channel bottom or walls [16].
330	canale	(Italian) Long drowned valley on the Dalmatian coast. Some canali may be drowned poljes [10].
331	cáno	(Spanish) Stream. See also stream.
332	canopy	1. Overhanging flowstone that projects from a cave wall. It may be a remnant of a once continuous false floor or a mass of flowstone that has built steadily outwards to create its own overhang [9]. 2. A compound cave formation consisting of flowstone hanging from a sloping wall projection and forming a fringe of shawls or stalactites on the outer edge [10].
333	canyon	1. A steep-walled chasm, gorge, or ravine cut by running water. 2. A chasm that has been formed by a cave stream. 3. A valley formed by collapse of the roof of a long fairly straight cave; a karst valley [10]. Related to corridor. Synonyms: (French) canyon, gorge, cañon; (German) Schlucht, Canyon; (Greek) pharangi; (Italian) forra, gola, orrido, canyon; (Russian) kanjon; (Spanish) cañón;, garganta; (Turkish) bogaz; (Yugoslavian) klanac, sutjeska, soteska, vintgar. See also bogaz; chasm; gorge; ravine.
334	canyon passage	1. A tubular passage (cave) that is formed by underground streams following gently tilted bedding-plane partings or fractures and are eroding channels downward through the rock. Their ceiling heights are greater than their widths. They are similar to surface canyons, but they possess roofs and are generally the same distance apart at the top as they are at the bottom. In Mammoth Cave, most are narrow and winding and may achieve dimensions of 50 feet wide by 100 feet high. If a canyon passage begins forming on an old tube passage, then a keyhole passage may result [15]. 2. Also known as vadose canyons, these are cave passages, most commonly formed by continued floor entrenchment or incision, by a free flowing vadose stream. The passage width at any particular level is determined by the flow of the formative stream, the rate of its downcutting and the effects of any subsequent collapse. Canyon height reflects the stream’s downcutting history. It depends upon the vertical distance available for erosional descent to the local base level and the time that erosional downcutting has been active, as well as upon the more obvious but less important influences of flow rate and erosional capacity. Vadose canyons commonly twist and meander sharply, while maintaining roughly parallel vertical sides. In contrast to some meanders in surface streams, underground meanders must generally be imprinted on a bedding plane before entrenchment of the canyon begins. Narrow canyon passages, commonly less than 1 m wide and more than 20 m high, are a particular feature of deep alpine caves. Perhaps the largest canyon passage in the world is that in Škocjanske Jama, Slovenia, which is over 100 m high and 50 m wide [9]. See paragenetic cave. See also keyhole passage; passage; tubular passage; vertical shafts.
335	capacity	The property to contain a certain volume or mass [16].
336	capacity, carrying	The capacity of a watercourse to transport solids [16].
337	capacity curve	A graphic presentation of the rate of discharge in a pipe or conduit or through porous material [16].
338	capacity, entrance	The property of a soil to let water infiltrate [16].
339	capacity, field; field-carrying; capillary	Soil moisture retained by capillarity and not removable by gravity drainage [16]. Synonym: specific retention.
340	capacity, ground-water	1. The ability of soil or rock materials to hold water. The yield of a pump, well, or reservoir.
341	capacity, hydraulic	The ability of a current of water or wind to transport detritus, as shown by the amount measured at a point per unit of time.
342	capacity, infiltration	The maximum rate at which a soil can absorb precipitation for given conditions [16].
343	capacity, self-cleaning	The capacity of a river to clean its water from pollutants over a given length of water course [16].
344	capacity, specific	The ratio of well discharge to corresponding discharge [16].
345	capacity, storage	1. The ability of an aquifer to store water [16]. 2. The capacity of rivers to store water in their own channels [16].
346	capacity, total	The maximum rate of yield of a well [16].
347	capacity, transmission	The property of a porous medium to conduct fluid [16].
348	capacity, well	The rate at which a well will yield water [16].
349	capillarity	The action by which a fluid, such as water, is drawn up (or depressed) in small interstices or tubes as a result of surface tension.
350	capillary action	The movement of water in the interstices of a porous medium due to capillary forces [22]. Synonymous with capillarity, capillary flow, and capillary migration.
351	capillary attraction	The adhesive force between a liquid and a solid in capillarity.
352	capillary condensation	The formation of rings of pendular water around point contacts of grains, and, when the rings around adjacent contacts become large enough to touch.
353	capillary conductivity	1. The property of an unsaturated porous medium to transmit liquid [22]. 2. Coefficient which expresses the extent to which an unsaturated permeable medium allows flow of water through its interstices, under a unit gradient of capillary potential [22].
354	capillary fringe	The lower subdivision of the unsaturated zone immediately above the water table in which the interstices are filled with water under pressure less than that of the atmosphere, being continuous with the water below the water table but held above it by capillary forces [22].
355	capillary fringe zone	The zone above the free water elevation in which water is held by capillary action.
356	capillary head	The potential, expressed in head of water, that causes the water to flow by capillary action [22].
357	capillary interstice	An interstice small enough to hold water by surface tension at an appreciable height above a free water surface, yet large enough to prevent molecular attraction from extending across the entire opening.
358	capillary migration	See capillary action.
359	capillary movement	The rise of water in the subsoil above the water table by capillarity.
360	capillary percolation	See imbibition.
361	capillary potential	The scalar quantity that represents the work required to move a unit mass of water from the soil to a chosen reference location and energy state [22].
362	capillary pressure	The difference in pressure across the interface between two immiscible fluid phases jointly occupying the interstices of a porous medium caused by interfacial tension between the two phases [22].
363	capillary rise	The height above a free water surface to which water will rise by capillary action [22]. Synonymous with height of capillary rise.
364	capillary stalagmite	Hollow stalagmite formed by saturated karst water pushed up through capillaries and small cracks in a sinter crust covering permeable fluvial deposits on the floor of a cave; first reported from Cuba, where such stalagmites are composed of aragonite [10].
365	capillary tension	See moisture tension.
366	capillary water	1. Water held in the soil above the phreatic surface by capillary forces [22]. 2. Soil water above hydroscopic moisture and below the field capacity [22].
367	carabiner	An oval of steel or aluminum with a movable spring-loaded gate on one side. A locking carabiner is one where the gate is threaded and has a ring that can be threaded over the gate opening to prevent it from opening [13]. Synonyms: karabiner; krab.
368	carbide, calcium carbide	A compound (CaC₂) of grayish color that reacts with water to produce acetylene gas and calcium hydroxide [Ca(OH)₂] [13]. Commonly used by cavers and miners earlier in this century as a means of providing light in caves or mines. Some cavers still prefer carbide lights over electric lights. See also carbide lamp.
369	carbide lamp	A carbide lamp, also known as a miners’ carbide lamp or acetylene lamp was introduced into mine use at about 1897. It consists of two chambers, a water tank above and a removable carbide canister below with a connection valve to permit controlled seepage of water into the calcium carbide. The carbide and water react to generate calcium hydroxide [Ca(OH)₂] and acetylene gas. The gas is passed through a filter into a tube and through a tiny burner-tip orifice designed for the optimum mixture of air and acetylene. Once ignited, it burns with a brilliant yellow-white flame produced by the incandescence of tiny carbon particles. A reflector concentrates the light in a particular direction [13].
370	carbonate	1. A salt or ester of carbonic acid; a compound containing the radical CO₃²⁻, such as calcium carbonate, CaCO₃. 2. A rock consisting mainly of carbonate minerals, such as limestone or dolomite [10].
371	carbonate-fluorapatite	A cave mineral — Ca₅(PO₄,CO₃)₃F [11].
372	carbonate hardness	Hardness of water due to presence of dissolved bicarbonates of calcium and magnesium which can be removed by boiling and hence the term “temporary hardness”. Synonyms: (French) dureté temporaire; (German) temporäre Härte, Carbonathärte; (Greek) parothiki sklipotis anthrakiki sklirotis; (Italian) durezza temporanea; (Russian) karbonatnaja zestkostj; (Spanish) dureza temporal; (Turkish) karbonat sertligi; (Yugoslavian) turdoóa, trdota.
373	carbonate-hydroxylapatite	A cave mineral — Ca₅(PO₄,CO₃)₃(OH) [11].
374	carbonate rock	A rock that consists of one or more carbonate minerals. Carbonate rock successions (or sequences) are those in which carbonate rock is dominant, but which also contain rocks of other lithology [9].
375	carbonic acid dissolution	Dissolution of calcium carbonate by carbon dioxide in aqueous solution, loosely termed carbonic acid, is the dominant reaction in karst processes, including speleogenesis. The reaction can be considered in several ways but it is most simply represented as: CaCO₃ + CO₂ + H₂O ⇌ Ca(HCO₃)₂ The reaction is reversible. The solution containing the dissolved reaction product, usually termed calcium bicarbonate, can lose carbon dioxide to the atmosphere and precipitate calcium carbonate. This process is responsible for the development of speleothems underground and tufa or travertine at the surface [9].
376	carnivore	An animal that lives by eating the flesh of other animals [23]. See also herbivore; insectivore; omnivore.
377	cascading water	In reference to wells, ground water which trickles or pours down the casing or uncased borehole above the water level in the well through cracks or perforations [22].
378	casing	Permanent liner of a well [16].
379	casing joint	Welded or threaded connection for tubular casing [16].
380	casing, surface	That part of a well casing that extends above land surface [16].
381	catch basin	1. A reservoir or basin into which surface water may drain. 2. A basin to collect and retain material from a street gutter that would not readily pass through a sewer system.
382	catchment	(Great Britain.) 1. An area into which surface water may drain. 2. A depression that collects rainwater (e.g., reservoir).
383	cation	An ion having a positive charge and, in electrolytes, characteristically moving towards a negative electrode [6].
384	cation exchange	Ion exchange process in which cations in solution are exchanged for other cations from an ion exchanger [6].
385	cation exchange capacity	The sum total of exchangeable cations that a porous medium can absorb. Expressed in moles of ion charge per kilogram of soil (or of other exchanges such as clay) [22].
386	causse	(French) A limestone plateau in the southeastern part of the central massif of France characterized by closed depressions, caves, and avens (jamas); a number of such plateaus in and around the basin of the river Tarn constitute Les Grandes Causses. This region was considered by Cvijić to exemplify karst development intermediate between holokarst and merokarst [10]. Synonym: (French) causse; (German) (Kalkstein Plateau), Cauße; (Greek) karstikón oropédion; (Italian) altopiano carsico; (Russian) izvestnjakovoje karstovoje plato; (Spanish) altiplano carstico; (Turkish) kireçtaşi düzlügü; (Yugoslavian) krs ̃ki plato, kras ̃ki plato.
387	cave	1. “A natural hole in the ground, large enough for human entry” is probably the most useful definition. This covers the enormous variety of caves that do occur but eliminates the many artificial tunnels and galleries incorrectly named caves. The size criterion is arbitrary and subjective, but practical, as it eliminates narrow openings irrelevant to explorers but very significant hydrologically, that may be better referred to as proto-caves, sub-conduits or fissures. A cave may be a single, short length of accessible passage, or an extensive and complex network of tunnels as long as the hundreds of kilometers in the Flint Mammoth Cave System. Most caves are formed by dissolution in limestone but sandstone caves, lava caves, glacier caves and tectonic caves also occur. Marginal candidates for use of the name cave include riverbank undercuts and rock shelters of various origins. In some countries a cave is regarded as being a horizontal opening, as opposed to a pothole, which is a vertical opening. This usage is common in England but is not ubiquitous [9]. 2. A natural opening formed in the rocks below the surface of the ground large enough for a man to enter. It may consist of a single connected opening or a series of small or large chambers connected by galleries [20]. 3. A similar artificial opening [10]. Related to cavern. Synonyms: (French) grotte, caverne; (German) Höhle, Grotte; (Greek) speleon; (Italian) caverna, grotta; (Russian) pescera; (Spanish) cueva; (Turkish) magara; (Yugoslavian) pec ̃ina. pec ̃, pes ̃tera, spilja, zijjalka, jama. See also active cave; bedding cave; cave system; grotto; sea cave.
388	cave balloon	See cave blister.
389	cave blister	1. A small pimplelike cave formation, roughly oval in shape, generally loose, and having a core of mud [10]. 2. A partly or completely hollow hemispherical to nearly spherical speleothem, usually of gypsum or hydromagnesite, attached to a cave wall. Synonym: cave balloon.
390	cave breakdown	1. Enlargement of parts of a cave system by fall of rock masses from walls and ceiling. 2. Heaps of rock that have collapsed from the walls and ceiling of a cave, generally called cave breccia [10]. 3. Synonym for the collapse of caves, or, in American usage, for the debris produced by collapse [18].
391	cave breathing	A resonance phenomenon in which air currents throb back and forth through constricted passages in a cave with periodicity of a few seconds to a few minutes. Synonyms: (French) passage respirant; (German) Grotte mit Resonanz; (Greek) anapneousa ope; (Italian) grotta a soffio alterno; (Spanish) gruta resonante; (Turkish) magara esintisi. See also blowing cave.
392	cave breccia	Angular fragments of rock forming a fill in a cave, either cemented together by dripstone or in a matrix of cave earth [10]. See also solution breccia.
393	cave bubble	A nonattached hollow sphere, usually of calcite, that has formed around a gas bubble on the surface of a cave pool.
394	cave coral	A rough, knobby growth of calcite resembling coral in shape, generally small; found on floor, walls, or ceiling of a cave [10]. Synonym: botryoid; coral formation; cave popcorn. See also knobstone.
395	cave cotton	Thin flexible filaments of gypsum or epsomite projecting from a cave wall. Synonym: gypsum cotton. See also gypsum flower.
396	cave development	The inception of cave development in carbonate rocks begins if water can move through the bedrock and commence dissolution. The earliest water movement may be due to mechanisms (including ground-water pumping and ionic diffusion effects) unrelated to those dominating later development. Similarly, inception may include physical and chemical dissolution (involving removal of carbonates and mineral impurities by water and by strong acids), as well as by the carbonic acid dissolution that dominates later cave growth. Initial water movement can be along primary pores in the rock (in coarse raffle limestones, oolites or chalk), along relatively thin non-carbonate beds within the succession, or along incipient or open fissures (joints, faults and bedding planes). These potential water routes are initially very narrow and water movement is severely restricted and laminar, allowing only very slow dissolutional growth (see gestation), until enlargement beyond the turbulent threshold (breakthrough) permits faster flow and accelerated cave growth. After establishment of turbulent flow conditions the effects of dissolution are augmented by mechanical abrasion and collapse, which expose new rock. During the early development stages a network of narrow openings is formed. Subsequently, geological factors guide the preferential expansion of favorable routes, which capture more of the local flow and enlarge, at the expense of less favorable openings, to form caves. The less favorable fissures are relegated to a subordinate role in transmitting percolation water or, more rarely, in carrying elements of overflow water during floods. Also during the early stages, all voids are water filled but as permeability increases and true hydraulic flow conditions are established, the upper voids drain freely, forming a water table. Almost all caves therefore originate under phreatic conditions but the overall passage morphology is modified during later growth into vadose or phreatic caves, enlarged from the original phreatic imprint, above or below the water table. Ultimately, cave development evolves towards efficient drainage close to the water table. Passage enlargement then becomes regressive as collapse increases. The stage of a cavernous karst collapsing extensively is relatively rarely achieved, being overtaken at high latitudes and high altitudes by surface lowering, but such collapse can contribute to the chaotic land forms of tropical karst [9].
397	cave earth, cave fill	Insoluble deposits of clay, silt, sand, or gravel flooring or filling a cave passage. In a more restricted sense, cave earth includes only the finer fractions: clay, silt, and fine sand deposits [10]. Synonym: cave soil.
398	cave ecology	The study of the interaction between cave organisms and their environment, e.g. energy input from surface, climatic influences [25].
399	cave fill	Transported materials such as silt, clay, sand and gravel which cover the bedrock floor or partially or wholly block some part of a cave [25].
400	cave flower	An elongate curved deposit of gypsum or epsomite on a cave wall in which growth occurs at the attached end [10]. Synonyms: gypsum flower; oulopholite. See also anthodite; cave cotton.
401	cave formations	1. Secondary mineral deposits formed by the accumulation, dripping, or flowing of water in a cave [10]. 2. Unsatisfactory term used to include all varieties of calcite, gypsum and other, rarer, mineral cave deposits; therefore a synonym for the equally unwieldly speleothem or the colloquial term “stall” [9]. See also sinter; speleothem.
402	cave group	A number of caves or cave systems, not interconnected but geographically associated in some relief feature or particular geological outcrop [10]. See also cave series.
403	cave guano	Accumulations of dung in caves, generally from bats; in some places partially mineralized [10].
404	cave ice	Ice formed in a cave by natural freezing of water. Loosely but incorrectly applied to calcium carbonate dripstone and flowstone [10].
405	cave-in	1. The collapse of the ceiling or side walls of a cave or of the land surface into a subterranean passage as a result of undermining or of pressure from above [10]. 2. The partial or complete collapse of earth material into a large underground opening, such as an excavation or a mine. 3. The sudden slumping of wall material into a pit. 4. A place where material has collapsed or fallen in or down.
406	cave-in lake	A shallow body of water whose basin is produced by collapse of the ground following thawing of ground ice in regions underlain by permafrost. Synonym: thermokarst lake.
407	cave lake	Any underground lake. The water can be in a partially drained phreatic cave, and may then be the entrance to a sump, or it can be open over its entire surface. In vadose caves lakes are most commonly formed by ponding behind banks of sediment or, in rarer cases, behind very large gour barriers [9].
408	cave marble	Banded deposit of calcite or aragonite capable of taking a high polish [10]. See also flowstone; onyx marble.
409	cave of debouchure	Outflow cave.
410	cave onyx	See onyx marble.
411	cave pearl	1. Carbonate concretion, usually of calcite, that is spherical or irregular in shape, with an internal structure of concentric banding round a central grain. Pearls form in pools of saturated water disturbed by dripping water, so that they are commonly found beneath high avens. Individual pearls may be lmm or many centimeters in diameter. Movement of the larger ones may become impossible and they can then become cemented to the pool floor. Some caves contain spectacular displays of cave pearls; in Jackson’s Bay Cave, Jamaica, they cover large areas of passage floor behind low gour barriers [9]. 2. Small concretion of calcite or aragonite formed by concentric precipitation around a nucleus [10]. Synonyms: pisolite; pisolith; (French) perle des cavernes; (German) Höhlenperlen; (Greek) speleomargarites; (Italian) perle di grotta; (Russian) pescernij zemcug; (Spanish) perla de caverna; (Turkish) magara incisi; (Yugoslavian) pećinski biseri, jamski biseri.
412	cave pisolite	See cave pearl.
413	cave popcorn	See cave coral.
414	cave postule	A white, hemispherical wall and roof deposit of calcite [25].
415	cave raft	A thin mineral film, usually of calcite, floating on a cave pool.
416	Cave Research Foundation (CRF)	An organization of cavers united primarily for scientific exploration and study of caves [13].
417	cave spring	See spring, cave.
418	caver	(American) 1. A slang term for one who engages in the hobby of cave exploration, or caving[9, 21]. 2. A person who explores caves in a safe manner while showing respect for the cave (all aspects of the cave), other cavers, and the land above the cave [13]. Synonym: spelunker; (British) potholer. See also speleologist.
419	cavern	1. Underground opening in soluble rock similar to a cave. When used as a noun, it refers to large openings, but when used as an adjective it tends to refer to rock texture and so to small openings. However, in some countries (e.g., Russia) cavern refers to small openings in a rock [20]. 2. A synonym of cave with the implication of large size. 3. A system or series of caves or cave chambers. 4. A cave, often used poetically or to connote larger-than-average size [10]. Synonyms: (French) caverne; (German) Höhle, Kaverne; (Greek) speleon; (Italian) caverna, grotta; (Russian) kaverna; (Spanish) caverna, cueva; (Turkish) kovuk; (Yugoslavian) kaverna. See also cave.
420	cavern breakdown	The process of cave enlargement which depends upon the mechanical failure and eventual collapse of sections of the cavern walls and ceiling [22].
421	cavern flow	Movement, often turbulent, of ground-water flow through caves, coarse sorted gravel, or large open conduits, either by gravity or under pressure.
422	cavernicole	An animal which normally lives in caves for the whole or part of its life cycle [25].
423	cavernous	Adjective used to describe a rock texture in which the rock contains openings generally of a small size [20]. Synonyms: (French) caverneux; (German) kavernös; (Greek) speleothes; (Italian) con grotte; (Russian) kavernoznij; (Spanish) cavernoso; (Turkish) kovuklu; (Yugoslavian) kavernozan. See also cavern.
424	cavernous karren	Pitted, rubbly limestone most commonly found in relatively recent and Tertiary limestones of the humid tropics [3]. See also covered karren; karren.
425	cavernous permeability	See conduit permeability.
426	cavernous rock	Any rock that has many cavities, cells, or large interstices (e.g., a cliff face pitted with shallow holes resulting from cavernous weathering).
427	cavernous weathering	Chemical and mechanical weathering on a cliff face, in which grains and flakes of rock are loosened so as to enlarge hollows and recesses.
428	cavern porosity	A pore system having large, cavernous openings. The lower size limit, for field analysis, is practically set at approximately the smallest opening that an adult person may enter.
429	cavern system	See cave system.
430	cave series	A group of caves of similar morphology in a particular district [10]. See also cave group.
431	cave shield	A semicircular plate of reprecipitated calcite located beneath joints in a cavern ceiling and believed to be formed by the seepage of hydrostatic water along the joint. Two shields form beneath one joint, descending from each side of the opening [22].
432	cave soil	See cave earth.
433	cave spring	See spring, cave.
434	cave system	1. An underground network of passages, chambers, or other cavities. 2. The caves in a given area related to each other hydrologically, whether continuous or discontinuous from a single opening [10]. Synonyms: (French) réseau souterrain; (German) Höhlensystem; (Greek) speleothes systema, thiction; (Italian) sistema carsico sotterraneo; (Russian) sistema podzemnih pescer; (Spanish) sistema de cavidades; (Turkish) magara sistemi, serisi; (Yugoslavian) pećinski (spiljski) sistem, amski sistem. See also cave; cave group; cave series; cavern.
435	caving	The sport of exploring caves. Synonyms: (British) potholing; spelunking. 2. A method of mining in which the ore is allowed to cave or fall [10].
436	cavings	Rock fragments that fall from the walls of a borehole and contaminate the well cuttings or block the hole. These fragments must be removed by drilling or circulation of drilling fluids before the borehole can be deepened.
437	cavitation	1. The collapse of bubbles in a fluid, caused by static pressure being less than the fluid vapor pressure. 2. A phenomena of cavity formation, or formation and collapse, especially in regard to pumps, when the absolute pressure within the water reaches vapor pressure causing the formation of vapor pockets [6].
438	cavity	A solutional hollow in a limestone cave.
439	cavity dweller	A coelobitic organism.
440	ceiling block	Roughly cubical joint-bounded large block, which has fallen from the ceiling of a cave [10]. See also cave breakdown; ceiling slab.
441	ceiling cavity	Solutional concavity in the ceiling of a cave. The orientation is determined by joints or a bedding plane [10].
442	ceiling channel	Sinuous channel developed in the ceiling of a cave, presumably during the phreatic phase of cave development [10].
443	ceiling meander	A winding upside-down channel in a cave ceiling [10].
444	ceiling pocket	See pocket.
445	ceiling slab, roof slab	A thin but extensive piece of rock that has fallen from the ceiling of a cave in roughly horizontal limestone [10]. See also cave breakdown; ceiling block.
446	ceiling tube	A half tube remaining in the ceiling of a cave [10].
447	celestite	A cave mineral — SrSO₄ [11].
448	cement	A microscopic textured nonskeletal void-filling material precipitated on an intragranular or intrasedimentary free surface that holds the material together [20]. Synonyms: (French) ciment; (German) Zement; (Greek) tsiménto; (Italian) cemento; (Spanish) cemento; (Turkish) çimento; (Yugoslavian) vezivo cement.
449	cementation	The process of binding granular material together by deposition of cementing material at contact points of grains [16].
450	cement grout	Cement slurry of pumpable consistency [16].
451	cement slurry	Liquid cement suspension [16].
452	cementing	See grouting.
453	cenote	(Spanish. after Mayan tzonet or dzonot.) 1. Steep-walled natural well that extends below the water table; generally caused by collapse of a cave roof. Term used only for features in Yucatán [10]. 2. Steep or vertical sided collapse doline floored by a lake whose surface is at the regional water table. The term originates from the many cenotes in the low karst plateau of Mexico’s Yucatan, but has been applied to flooded dolines in Florida and elsewhere. Probably the most famous cenote is the sacred well of Chichen Itza, Yucatan; it has vertical sides and is 60m in diameter, 30m deep and half full of water [9]. Synonyms: (French) cenote; (German) cenote; (Greek) voulismeno speleven. See also jama; natural well.
454	centrifuge moisture equivalent	See moisture equivalent.
455	cerussite	A cave mineral — PbCO₃ [11].
456	chain gage	Water level measuring device [16].
457	chalk	1. Used as a proper noun chalk describes a rock unit of Cretaceous age, that consists predominately of relatively soft, white, porous limestone with beds of marl and bands or nodules of flint. The term is used without its initial capital to describe any rock with similar appearance and properties. Generally chalk has a relatively high primary permeability and so rarely develops caves of explorable size, though conduit-water flow does occur. Some harder chalks in northern France and south-eastern England hold explorable active and relict caves, which extend for many hundreds of meters [9]. 2. Soft poorly indurated limestone, generally light in color; commonly composed of the tests of floating microorganisms in a matrix of very finely crystalline calcite [10].
458	chalcanthite	A cave mineral — CuSO₄·5H₂O [11].
459	chamber	(American) 1. An enlargement in a cave passage or system, commonly formed at a junction of passages, or locally in a single passage, where erosion has been enhanced by collapse exposing more rock to dissolution. Maximum chamber size is controlled by the strength and shape of the limestone ceiling. The largest chamber currently known, Sarawak Chamber in Lubang Nasib Bagus, at Mulu, Sarawak, is over 700m long, up to 400m wide and nowhere less than 70m high. It has formed where a large stream eroded sideways as it cut obliquely across the included bedding in unusually massive limestone. It is doubtful whether a much larger chamber could exist without collapse of its roof [9]. 2. The largest order of cavity in a cave or cave system; it has considerable length and breadth but not necessarily great height. 3. (British) A room in a cave [10]. Synonyms: (French) salle; (german.) Halle, Kammer, Dom; (Greek) ypoyios aethousa; (Italian) sala; (Russian) zal; (Spanish) sala, salón; (Turkish) oda; (Yugoslavian) dvorana. See also room; passage.
460	chandelier	Large variety of gypsum flower, with branching crystal structure that may hang many meters from a cave ceiling. Very rare, except in Lechuguilla Cave of New Mexico [9].
461	channel	Natural or artificial watercourse bounded by banks [16].
462	channel characteristics	Hydraulic properties of stream channel [16].
463	chasm	1. A deep, fairly narrow breach in the earth’s surface; an abyss; a gorge; a deep canyon. 2. A deep, wide, elongated gap in the floor of a cave [10]. Related to canyon, corridor. Synonyms: (French) gouffre, fracture ouverte; (German) Kluft; (Greek) chasma; (Italian) fattura beante, canyon; (Spanish) cañon, taso; (Turkish) derin yarıntı; (Yugoslavian) provalija. See also ravine.
464	chemical carbonate rock	Carbonate rock form by the precipitation of mineral matter in situ by chemical or biological processes.
465	chemical deposit	A sediment precipitated out of solution by chemical action [16].
466	chemical erosion	Processes partially synonymous with chemical dissolution, but including any other form of rock breakdown accelerated by chemical changes of the constituent minerals [9].
467	chemical equivalent	The expression of water characteristics such as hardness or alkalinity resulting from several ions in solution in terms of only one equivalent concentration [16].
468	chemical mobility	The tendency of an element to move in a given hydrogeochemical environment [16].
469	chemical oxygen demand (COD)	The measure of readily available oxidizable material contained in a water sample [16].
470	chert, chert nodule	1. Black, brown or grey rock, consisting of very fine-grained silica, that occurs as horizons of nodules and discontinuous bands, generally less than 200mm thick, within many limestones. It is very hard and almost insoluble in water, so commonly it projects from cave walls where it forms passage or shaft ledges and waterfall lips [9]. 2. Light-cream or gray to black rock composed of silica, found occurring as nodules or layers in limestone, or as a replacement of limestone [10].
471	Chézy equation	An equation used to compute the velocity of uniform flow in an open channel: mean velocity of flow (V) equals the Chézy coefficient C times the square root of the product of hydraulic radius in feet (R) times the slope of the channel [1]. See also Froude number; Manning equation; Reynolds number. [GP: This text under review.]
472	chimney	1. Nearly circular shaft rising upwards from the ceiling of a cave towards the surface of the ground; if it does not reach the surface it is termed a blind chimney. If the chimney is formed mainly by solution, it is related to a dome-pit; if formed mainly by collapse of the roof along bedding planes, it is related to cenote [20]. 2. A narrow vertical shaft in the roof of a cave, generally smaller than an aven; a dome pit [10]. Synonyms: (French) cheminée (aven); (German) Schlot, Kamin; (Greek) kapnothochos; (Italian) camino; (Russian) truba; (Spanish) chimenea; (Turkish) baca; (Yugoslavian) dimnjak.
473	chimneying	Ascending or descending by means of opposed body and/or limb pressures against two facing walls [25].
474	chlorophyll	A group of pigments producing the green color of plants; essential to photosynthesis [23].
475	chock	A block of metal for use as a chockstone [25].
476	chockstone	A rock wedged between the walls of a cave passage [10].
477	choke	1. A blockage of inwashed mud, sand or boulders in a cave passage. Most boulder chockes are formed by collapse of a passage roof and may have an open chamber or shaft above them; others are formed by collapse and inwashed debris where a large old passage is cut by a hillside. A passable route through a choke may be opened by excavation, and thereby lead to discovery of new passage — as was done so successfully in Ogof Agen Allwedd [9]. 2. Rock debris or cave fill completely blocking a passage [10].
478	C-horizon	Zone of weathered parent material in a soil profile [16].
479	chute	An inclined channel or trough in a cave [10].
480	ciénaga	(Spanish) Wetland. See also wetland.
481	cimolite	A cave mineral — Al₄(SiO₂)₉(OH)₁₂ [11].
482	cistern	A small water reservoir used to collect surface and rain water [16].
483	classical karst	Originally the region called Kras in Slovenia, which gave its name to the karst landscape. Used in this sense about 95% of the classical karst lies in Slovenia, with the remaining 5% extending to Italy. A slightly different area was covered by descriptions of early investigations or karst phenomena, when the name classical karst was applied to a region between Ljubljana, Gorizia and Rijeka, mainly in Slovenia with some parts in Italy and Croatia [9].
484	clastic	Pertaining to a rock or sediment composed principally of broken fragments that are derived from pre-existing rocks or minerals and that have been transported some distance from their places of origin [6].
485	clastic carbonate rock	Carbonate rock that is made up of carbonate grains (e.g., shells, shell fragments, oolites).
486	clastic rock; detrital rock	A sedimentary rock derived from fragmentated other preexisting rock or organic structures [16].
487	clastokarst	Karst phenomena in clastic rocks composed of detrital carbonate material [20]. Synonyms: (French) clastokarst; (German) Klastokarst?; (Greek) clastokarst; (Italian) carsismo clastico; (Russian) klastokarst; (Spanish) clastokarst; (Turkish) klastik karst; (Yugoslavian) klastokrs̃, klastokras, klastokarst.
488	claustrophobia	An irrational fear of being in a closed space [25].
489	clay	1. A rock or mineral fragment or a detrital particle of any composition smaller than a very fine silt grain, having a diameter less than 1/256 mm (4 microns, or 0.00016 in., or 8 phi units.) This size is approximately the upper limit of size of particle that can show colloidal properties. 2. A loose, earthy, extremely fine-grained natural sediment or soft rock composed primarily of clay-size or colloidal particles and characterized by a considerable content of clay minerals and subordinate amounts of finely divided quartz, decomposed feldspar, carbonates, ferruginous matter, and other impurities. It forms a plastic, moldable mass when finely ground and mixed with water, but retains its shape on drying, and becomes firm, rocklike, and permanently hard on heating or firing. 3. A term that is commonly applied to any soft, adhesive, fine-grained deposit (such as loam or siliceous silt) and to earthy material, particularly when wet (such as mud). 4. A term used by the International Society of Soil Science for a rock or mineral particle in the soil, having a diameter less than 0.002 mm (2 microns).
490	clay ball, clayball	A chunk of clay released by erosion of a clayey bank and rounded by wave action.
491	clay boil	A mud circle that suggests a welling-up or heaving of the central core.
492	clay colloid	1. A clay particle having a diameter less than 1 micron (0.001 mm.) 2. A colloidal substance consisting of clay-size particles.
493	clay fill	Dry or wet clay that fills a cave passage [10].
494	clay filling	Time interval between end of phreatic solution of a cave and beginning or deposition of flowstone [10].
495	clayey sand	1. An unconsolidated sediment containing 50–90% sand and having a ratio of silt or clay less than 1:2. 2. An unconsolidated sand containing 40–75% sand, 12.5–50% clay, and 0–20% silt.
496	clayey silt	1. An unconsolidated sediment containing 40–75% silt, 12.5–50% clay, and 0–20% sand. 2. An unconsolidated sediment containing more particles of silt size than of clay size, more than 10% clay, and less than 10% of all other coarser sizes.
497	clay loam	A soil containing 27–40% clay, 20–45% sand, and the remainder silt.
498	clay marl	1. A whitish, smooth, chalky clay. 2. A marl in which clay predominates.
499	clay mineral	One of a complex and loosely defined group of finely crystalline, metacolloidal, or amorphous hydrous silicates, essentially of aluminum.
500	claypan	A dense, heavy, relatively impervious subsurface soil layer that owes its hardness to a relatively higher clay content than that of the overlying material from which it is separated by a sharply defined boundary.
501	clay parting	1. Clayey material between a vein and its wall. 2. A seam of hardened carbonaceous clay between or in beds of coal, or a thin layer of clay between relatively thick beds of some other rock (e.g., sandstone).
502	clay plug	Fine flood deposits in a cut off river meander [16].
503	clean sand	Sand with little or no clay content [16].
504	cleavage	The tendency to cleave or split along definite parallel planes, which may be highly inclined to the bedding. It is a secondary structure and is ordinarily accompanied by at least some recrystallinization of the rock.
505	climate	The average weather conditions of an area, including temperature, rainfall, humidity, wind, and hours of sunlight, based on records kept for many years [23].
506	climatic factor	A factor influencing hydrologic parameters due to the local climate [16].
507	clinometer	An instrument for measuring vertical angles or angles of dip [25].
508	clint	(British) 1. Flat or sloping bare limestone outcrops (limestone pavements) weathered into straight-sided or furrowed blocks and ridges of limestone which are separated by deep clefts or solutionally widened joints (grikes) that often crisscross [20]. 2. Slabs of limestone, parallel to the bedding, forming a pavement. Widened joints, or grikes, isolate individual clints [10]. Synonym: (French) lapiaz; (German) Flachkarren, Karrenfeld; (Greek) pethion amaxotrochion thactyloglyphon; (Italian) campo carreggiato; (Russian) karrovoe pole; (Spanish) campo de lapiaz, lenar; (Turkish) pürtüklü, oluklu; (Yugoslavian) škrapari, škraplje. See also grikes; karrenfeld; lapies; limestone pavement.
509	clog, to	The action of blocking fluid flow paths, especially around a well bore [16].
510	clogger	A type of ascender without a handle; used with a karabiner to keep it securely on the rope [25].
511	closed depression, closed basin	1. Any karst hollow with internal drainage, including dolines, uvalas, poljes, cockpits and all varieties of blind karst valleys, of both small and large scales [9]. 2. A general term for any enclosed topographic basin having no external drainage, regardless of origin or size [10].
512	closed karst	A karst terrane that is covered by sediments. Synonyms: (Russian) skrytyĭ karst or zakrytyĭ karst. See also buried karst; interstratal karst; mantled karst.
513	closed traverse	A traverse which begins and ends at survey points with known co-ordinates and orientation or at the same point [25].
514	cloud	Large masses of coralloid or botryoidal calcite, deposited under water, with each mass reaching 200–800mm in diameter. Famous examples hang above the Lake of the Clouds in Carlsbad Cavens, New Mexico [9].
515	clusterite	See botryoid.
516	coarse	Composed of or constituting relatively large particles.
517	coarse sand	1. A geologic term for a sand particle having a diameter in the range of 0.5–1 mm (500–1000 microns, or 1 to zero phi units.) 2. An engineering term for a sand particle having a diameter in the range of 2 mm. 3. A soil term used in the U.S. for a sand particle having a diameter in the range of 0.5–1 mm (the diameter range recognized by the International Society of Soil Science is 0.2–2 mm).
518	coarse silt	A geologic term for a silt particle having a diameter in the range of 1/32 to 1/16 mm (31–62 microns, or 5 to 4 phi units).
519	cockpit	(Jamaican) 1. Any closed depression having steep sides. 2. A star-shaped depression having a conical or a lightly concave floor. The surrounding hill slopes are steep and convex. Cockpits are the common type of closed depressions in a kegelkarst [10].
520	cockpit karst	(Jamaican) 1. Term describing an area containing numerous scattered, yet closely spaced dolines; generally a tropical karst land form. The corresponding Yugoslav term may more accurately be translated as “pock-marked” karst. 2. Tropical karst topography containing many closed depressions surrounded by steep-sided conical hills. Divided by French and German geographers into several types depending on shape of hills [10]. Synonyms: (French) karst cockpit; (German) Turmkarst, Kegelkarst; (Greek) dolinovrithes karst; (Italian) campo carsico a doline; (Spanish) karst esponja; (Turkish) düdenli karst; (Yugoslavian) boginjavi krś, kozavi kras. See also cone karst; Halbkugelkarst; Kegelkarst; Spitzkegelkarst; tower karst.
521	coefficient of compressibility	Compressibility is the aptitude of the soil to be deformed. It is expressed by means of a coefficient which is the ratio between a void ratio decrease from e₀ to e and an increase in effective stress. The value a_v = e₀–eΔp represents the coefficient of compressibility for the range p₀ to p₀ + p. Units are usually cm²/kg [21]. See also coefficient of volume compressibility.
522	coefficient of permeability	An obsolete term that has been replaced by the term hydraulic conductivity [6].
523	coefficient of storage	See storage coefficient.
524	coefficient of transmissivity; coefficient of transmissibility	An obsolete term replaced by the term transmissivity.
525	coefficient of volume compressibility	The compression of a clay (aquitard) per unit thickness, due to a unit increase of effective stress, in the load range exceeding preconsolidation stress. It is expressed by the equation: m SUB v = {a SUB v} OVER {1 + e SUB 0} in which e₀ is the initial void ratio. Units are usually cm²/kg [21]. See also coefficient of compressibility.
526	cohesion	Shear resistance at zero normal stress. An equivalent term in rock mechanics is intrinsic shear strength.
527	coliform organism	A microorganism, the concentration of which is used as an indication of the degree of biological pollution of water [16].
528	collapse breccia	A mass of rock composed of angular to rounded fragments of limestone or dolomite that has formed as the result of the collapse of the roof of a cave, of an underlying cave, or of an overhanging ledge [10]. See also solution breccia.
529	collapse chamber	An underground chamber containing notable quantities of collapsed material. The term is commonly abused in describing the origin of cave chambers floored by collapse debris. Though wall and roof collapse are common modifying processes in larger chambers, it is important to remember that such collapse cannot form a chamber, as it can only take place into a pre-existing cavity [9].
530	collapse sink; collapse sinkhole	1. A variety of closed depression that forms by collapse of the rock above an existing cave passage or chamber [9]. 2. A closed depression formed by the collapse of the roof of a cave [10]. See also doline.
531	collapse of caves	Collapse and breakdown of cave walls and ceilings are continuing aspects of cave development and modification. Massive unfractured limestone can easily span a void of over 100m, but thinly bedded, closely jointed, faulted or poorly lithified limestone may collapse into very small passages. Collapse is a significant component of cave erosion. As well as simple falls of unsupported rock forming connections between passages, the collapse process exposes more rock surface area for potential dissolution. As rates of collapse are measured on a geological time scale collapse in natural caves offers a negligible threat to explorers, in comparison to the dangers of roof collapse in mines [9].
532	collector well	A central well with horizontal sections of screened collector pipe arranged radially to increase yield [16].
533	colloid	Extremely small solid particles, 0.0001 to 1 micron in size, which will not settle out of solution. It is intermediate between a true dissolved particle and a suspended solid which will settle out of solution [6].
534	column	1. A subsurface dripstone formation produced by the union of a stalactite and a stalagmite in a cave [20]. 2. A flowstone formation, generally cylindrical, formed by the union of a stalactite and stalagmite [10]. Not to be confused with pillar. Synonyms: (French) colonne, pillier stalamitique; (German) Tropfstein-Säule; (Greek) stalaktitike stele; (Italian) colonna (stalagmitica o stalattitica) (Russian) kolonna; (Spanish) columna; (Turkish) sütun; (Yugoslavian) stup, steber, stolpic̃. See also pillar.
535	comminution	The reduction of a substance to a fine powder; pulverization; trituration.
536	community	All the plants and animals that live in a particular habitat and are bound together by food chains and other interrelations [23].
537	compaction	A decrease in the volume of a mass of sediments from any cause. In general, compaction may be regarded as the decrease in the thickness of sediments, as a result of an increase in vertical compressive stress, and is synonymous with “one-dimensional consolidation”, as used by engineers. The term compaction is applied both to the process and to the measured change in thickness. In thick fine-grained beds, compaction is a delayed process involving the slow escape of pore water and the gradual transfer of stress from neutral to effective. Until sufficient time has passed for excess pore pressure to decrease to zero, measured values of compaction are transient [21]. See also compaction, residual; compaction, specific.
538	compaction, residual	Compaction that would occur ultimately if a given increase in applied stress were maintained until steady-state pore pressures were achieved, but had not occurred as of a specified time because excess pore pressures still existed in beds of low diffusivity in the compacting system. It can also be regarded as the difference between (1) the amount of compaction that will occur ultimately for a given increase in applied stress, and (2) that which has occurred at a specified time [21]. See also compaction; compaction, specific.
539	compaction, specific	The decrease in thickness of deposits, per unit of increase in applied stress, during a specific period of time [21]. See also compaction; compaction, residual.
540	compass	An instrument with a magnetic needle which is free to point to magnetic north. For survey the needle is either attached to a graduated card or can be read against a graduated circle to measure the angle in degrees from the north clockwise [25].
541	competition	The struggle between individuals or groups of living things for common necessities, such as food or living space [23].
542	complete well penetration, fully penetrating	1. The property of a well that penetrates an aquifer completely from the upper confining bed or water table to the lower confining bed [16]. 2. A well that is completed over the whole thickness of the aquifer to allow radial production over its entire completed length [16].
543	compressibility	The relative change in volume with pressure of water or aquifer matrix [16].
544	compressive stress	Normal stress tending to shorten the body in the direction in which it acts.
545	compromise boundary	1. A plane interface between two crystals which evolved by mutual interference of their respective growing faces. This interface is a face of neither crystal. 2. A microscopic texture [20].
546	concentration gradient	The change in solute concentration per unit distance in solute. Concentration gradients cause Fickian diffusion (spreading) of solutes from regions of highest to regions of lowest concentrations. In slowing moving ground water, this is the dominant mixing process [22].
547	concretion	The localized deposition of mineral matter going out of solution in sediments or tuffs, usually nodular or irregular in shape [16].
548	condensation	The transition from vapor to liquid state [16].
549	condensation nucleus	A small solid particle around which condensation occurs [16].
550	condensation water	Atmospheric moisture deposited inside caves when the surface temperature of the exposed rock falls below the dew point of circulating air [19].
551	conduit; karst conduit	Relatively large dissolutional voids, including enlarged fissures and tubular tunnels; in some usage the term is restricted to voids that are water-filled. Conduits may include all voids greater than 10mm in diameter, but another classification scheme places them between arbitrary limits of 100mm to 10m. Whichever value is accepted in a particular context, smaller voids are commonly termed sub-conduits [9]. Synonyms: (French) conduite forcée; (German) Druckleitung (Leitung); (Greek) siphon; (Italian) condotta forzata; (Spanish) conducto saturado; (Turkish) yeraltısu yolu, mecra. See also pressure flow tube; stream tube; siphon.
552	conduit flow; karst conduit flow	Underground water flow within conduits. Conduit flow is generally turbulent, but can also be laminar [9].
553	conduit permeability	Sometimes referred to as cavernous permeability, this is a measure of the efficiency with which a particular aquifer transmits water through conduits (see permeability) [9].
554	conduit porosity	That part of the porosity within an aquifer (usually a karst aquifer) that is a function of the presence of conduits [9].
555	cone of depression	A depression of the potentiometric surface in the shape of an inverted cone that develops around a well that is being pumped. It defines the area of influence [6]. Synonym: cone of pressure relief (applied to artesian aquifers only).
556	cone of impression	A rise of the potentiometric surface in the shape of a cone that develops around an injection well [22].
557	cone karst	1. A karst landscape dominated by low conical (or hemispherical) hills that forms only in wet tropical climates. The type example is Gunung Sewu in Java. Individual hills are remarkably uniform, each some few hundred meters in diameter and around 50m high. Between them lie broken valleys, dolines or cockpits, draining into sinkholes. Erosion that seems to be initiated in valley systems develops in such a way that the valleys break up into dolines, but the mechanisms leading to uniform shaping of the hills are not fully understood. The widespread cone karst in China is mostly known as fengcong, and its hills are generally more conical than hemispherical in profile [9]. 2. A type of karst topography, common in the tropics, characterized by star-shaped depressions or dolines at the feet of many steep-sided cone-shaped hills; narrow steeply-walled valleys may be present[10, 20]. A variety of Kegelkarst. Synonyms: (French) karst à pitons; (German) Kegelkarst, Turmkarst; (Greek) konoethes karst; (Italian) carso di torri, carsismo con forme residuali coniche; (Russian) karst s koniceskimi ostancami; (Spanish) karst de conos; (Turkish) konili karst; (Yugoslavia) stožasti krš, čokasti kras stožčsti, kras. See also cockpit karst. Compare: cupola karst, pinnacle karst, and tower karst.
558	confined	A modifier which describes a condition in which the potentiometric surface is above the top of the aquifer [22]. Synonymous with artesian.
559	confined aquifer	1. An aquifer bounded above and below by confining units of distinctly lower permeability than that of the aquifer itself. 2. An aquifer containing confined ground water. Generally, a confined aquifer is subject to pressure greater than atmospheric [6].
560	confined water	Water separated from the atmosphere by impermeable rock stratum [16].
561	confining bed	A body of impermeable or distinctly less permeable material stratigraphically adjacent to one or more aquifers [22]. Synonymous with confining unit.
562	confining unit	1. A hydrogeologic unit of impermeable or distinctly less permeable material bounding one or more aquifers and is a general term that replaces aquitard, aquifuge, aquiclude [22]. 2. Means a body of impermeable or distinctly less permeable material stratigraphically adjacent to one or more aquifers [22]. Synonymous with confining bed.
563	confining zone	A geological formation, group of formations, or part of a formation that is capable of limiting fluid movement above an injection zone [22]. See confining unit.
564	confluence	Junction point of streams [16].
565	conformal mapping	The transposition and solution of plane flow problems in a complex plane [16].
566	conglomerate	Rock consisting of large well rounded waterworn particles [16].
567	conical wall niche	See meander niche.
568	conjugate joints or faults	Two sets of joints or faults that are formed under the same stress conditions (usually shear pairs).
569	conjunctive use	The use of both surface water and ground water [16].
570	connate water	Water entrapped in the interstices of a sedimentary or extrusive igneous rock at the time of its deposition [22].
571	consequent river	A river flowing down the original slope of geologic beds or general slope of topography [16].
572	conservation	The use of natural resources in a way that assures their continuing availability to future generations; the wise use of natural resources.
573	consolidation	1. The binding of grains by cementing material to solid matrix [16]. 2. The gradual reduction in the water content (void ratio) of a saturated soil, as a result of an increase in the pressure acting on it, because of the addition of overlying sediments or the application of an external load. A laboratory test commonly known as a one-dimensional consolidation test (odometric test), is performed on soil samples to evaluate consolidation. From such a test, the coefficient of consolidation, c_v usually expressed in cm²/sec, is calculated as the ratio: c SUB v = {K CDOT l} OVER {m SUB v CDOT ITAL gamma SUB w} where K is the hydraulic conductivity, m_v is the coefficient of volume compressibility, and γ_w is the unit weight of water. The theory of consolidation leads to a relation between degree of consolidation and time: U% = {c SUB v CDOT t} OVER H SUP 2 In this expression U is the degree of consolidation or the percentage of total consolidation occurring in some time t; c_v is the coefficient of consolidation; and H is half of the sample’s thickness when the odometric test is performed [21].
574	consolidated rock	Rock that has become hard and coherent through compression and lithification [16].
575	constant-temperature zone	The area of a cave where air temperature is unchanging throughout the year and approximates the average annual temperature aboveground [23]. See also zonation.
576	constructive waterfall	A large rimstone dam on a surface stream [10]. See rimstone dam. Synonyms: (French) chute incrustante; (German) Waßerfall, inkrustierender?, Sinter…?, Sinterbecken; (Greek) katarráktis; (Italian) (vasche d’incrostazione); (Spanish) dique travertínico; (Turkish) düşüm; (Yugoslavian) slap, prec ̃aga.
577	consumer	Any living thing that is unable to manufacture food from nonliving substances, but depends instead on the energy stored in other living things [23]. See also carnivore; decomposers; food chain; herbivore; omnivore; producers.
578	consumptive use	The quantity of water used annually by crops or natural vegetation due to transpiration, tissue building, and evaporation from adjacent soil [16].
579	contact load	The solid material in sliding or rolling contact with a stream bed [16].
580	contact spring	See spring, contact.
581	contaminant	1. An undesirable substance not normally present or an unusually high concentration of a naturally occurring substance in water or soil [22]. 2. Any physical, chemical, biological, or radiological substance or matter in water [22]. See also pollutant.
582	contaminant plume	An elongated body of ground water containing contaminants, emanating and migrating from a point source within a hydrogeologic unit(s) [22].
583	contaminate	To introduce a substance that would cause (a) the concentration of that substance in the around water to exceed the maximum contaminant levels; or (b) an increase in the concentration of that substance in the ground water where the existing concentration of that substance exceeds the maximum contaminant levels [22]. See also pollutant.
584	contamination	The addition to water of any substance or property preventing the use or reducing the usability of the water. There is no specific limits, since the degree of permissible contamination depends upon the intended end use, or uses, of the water [6]. Sometimes considered synonymous with pollution.
585	continuous stream	A stream that is continuous in space from source to discharge point [16].
586	contributing region	That region which contributes to well discharge in inclined water-table flow [16].
587	control	The combined effect of channel characteristics (area, shape, slope, roughness) on rating curve [16].
588	conulite	A hollow, cone-shaped speleothem formed when a conical depression is drilled in cave mud by falling water. Subsequent erosion may remove the mud, isolating the calcite lining of the depression [10].
589	convective diffusion	See mechanical dispersion, coefficient.
590	convective transport	The component of movement of heat or mass induced by thermal gradients in ground water [22]. See also advection.
591	convection	The process whereby heat is carried along with the flowing ground water [22].
592	convergence	Net horizontal inflow of moisture per unit area [16].
593	cooling water	Water used only for cooling purposes [16].
594	cool spring	Spring water temperature below mean annual surface temperature [16].
595	coprolite	The fossilized excrement of vertebrates such as fishes, reptiles, an mammals, larger than a fecal pellet, measuring up to 20 cm in length, characterized by an ovoid to elongate form, a surface marked by annular convolutions, and a brown or black color, and often composed largely of calcium phosphate; petrified excrement [1].
596	coprophage	A scavenger which feeds on animal dung, including guano [25].
597	coquina	Porous limestone composed of broken shell fragments [16].
598	coralloid speleothem	Any variety of microcrystalline, coralloid or botryoidal calcite deposit that is distinguished by curved outer surfaces and curved internal structures. Large examples, including clouds, are formed under water. Smaller varieties, also known as cave coral and cave popcorn, are splash deposits, or are precipitated onto cave passage walls from mists or thin surface films of saturated water [9].
599	corrasion	Mechanical erosion performed by such moving agents as water, ice, and wind, especially when armed with rock fragments [10]. See also corrosion.
600	corridor	1. Long, narrow chasm enlarged by action of water and into which surface runoff or stream may flow; may be located along a fault plane, fissure, joint or between two beds. Struga (Slavic) refers to such a corridor along a bedding plane in a carbonate formation [20]. 2. Relatively narrow passageway permitting travel between two larger areas. 3. A fairly level and straight passage that links two or more rooms or chambers in a cave. 4. Intersecting linear depressions on the surface of the land, related to joints or dikes [10]. See also bogaz; struga; zanjón. Related to chasm; bogaz. Synonyms: (French) gouffre absorbant; (German) Karstgaße; (Greek) apocheteftikos karstikos agogos; (Italian) dolina allongata; (Russian) coridor, hod; (Spanish) callejón; (Turkish) koridor; (Yugoslavian) struga, bogaz.
601	corrasion	Abrasion of the rock floor and walls of a stream channel by rock debris carried in the water [9].
602	corrosion	1. Chemical action of water containing carbonic acid (also humidic, nitric, and other acids) on limestones and dolomites causing partial solution and related chemical changes in the rocks [20]. 2. Erosion by solution or chemical action [10]. 3. The act or process of dissolving or wearing away metals [6]. See also accelerated corrosion; alluvial corrosion; corrasion; solution. Compare aggressive water. Synonyms: (French) corrosion; (German) Korrosion; (Greek) chemeke thiavroses; (Italian) dissoluzione, corrosione; (Russian) korrozija; (Spanish) corrosión; (Turkish) eritme, yenme, kemirilme; (Yugoslavian) korozija.
603	corrosive	Property of aggressive water.
604	coupole	(French) Cupola or hemispheric hill [10].
605	cove	(Southern Appalachians.) Narrow steep-sided karst valley flanking limestone plateaus [10].
606	covered karren	Any karren that is covered by soil. Draining water is oversaturated with respect to CO₂ so that corrosion is extensive [3]. See also wave karren; root karren; cavernous karren.
607	covered karst	1. A fossil or currently developing karst in karst limestone which underlies superficial deposits or other rock, and which may produce landforms at the surface which reflect subsurface karstification [19]; contrasted with naked karst, which is soil free. See also buried karst; interstratal karst; mantled karst; subsoil karst; sulfate-reduction karst. 2. A generally subdued karst landscape developed where carbonate rocks are affected by dissolutional processes beneath a soil cover (see bare karst) [9]. Synonyms: (French) karst couvert; (German) Bedeckter karst; (Greek) kekalymenon karst; (Italian) carso coperto; (Russian) pokrytyĭ karst, pokritij karst; (Spanish) karst cubierto; (Turkish) örtülü karst; (Yugoslavian) pokriveni krš, pokriti kras.
608	cow’s tail	A length of rope used as a safety when crossing a rebelay [25].
609	crack	1. Tight joint [16]. 2. A small fracture (i.e. small with respect to the scale of the feature in which it occurs).
610	crandallite	A cave mineral — CaAl₃(PO₄)₂(OH)₅·H₂O [11].
611	crawl, crawlway	A cave passage that is large enough to be negotiated on hands and knees [10] or so small as to require a caver to squeeze through on his/her back or belly [13].
612	creek, brook	Watercourse of lesser volume than a river.
613	crescentic wall niche	See meander niche.
614	crest line	Line connecting crests [16].
615	crest segment	The top part of a hydrograph [16].
616	crest-stage indicator	A mechanical gage that preserves the indication of highest water level rise [16].
617	crevice	Opening in a rock formation or glacier [16].
618	crevice karst	An intricate irregular crevice system that has formed by solution widening of closely spaced joints. Crevices may be as much as 6 meters across and 20 meters deep. Especially well developed near rivers in lowland New Guinea [10].
619	critical depth	The depth of flow in open channels when specific energy is minimum [16].
620	critical depth flume	Venturi or Parshall flume for discharge measurements [16].
621	critical flow	Open channel flow with Froude Number equal to unity [16]. See also Froude Number.
622	crooked hole	Borehole deflected from the vertical [16].
623	cross bedding	Oblique deposition of thin beds with respect to the main planes of stratification [16].
624	cross fault	A geologic fault that is oblique or at right angles to the strike direction of the beds.
625	cross section	1. Vertical section of a geologic profile [16]. 2. A section of a cave passage or a chamber across its width [25].
626	crust stone	A fragile layer of flowstone covering portions of walls of caves; looks like a flaky crust. Found in some Kentucky caves [10].
627	crustaceans	The large class of animals that includes lobsters, crayfish, amphipods, isopods, and many similar forms. Crustaceans typically live in water and have many jointed appendages, segmented bodies, and hard exoskeletons [23].
628	cryokarst	1. A non-karstic term. Land surface with closed depression (usually small and shallow) formed by alternate freezing and thawing of permafrost or ground-ice overlying different rock, including limestone. The term “cryokarst” is more common in Europe while the term “thermokarst” is used in America [20]. 2. A karst-like periglacial, or formerly periglacial, landscape superimposed upon unconsolidated, superficial deposits. Cryokarst is characterized by small depressions or pits that develop due to settlement of overlying deposits into voids formed by the melting of entrapped ice. Also known as thermokarst [9]. Synonyms: (French) cryokarst, thermokarst; (German) Thermokarst, Cryokarst; (Greek) thermokarst; (Italian) criocarsismo; (Russian) temokarst, criokarst; (Spanish) criokarst, thermokarst; (Turkish) don karstı; (Yugoslavian) toplotni krs̃, temokarst.
629	cryptokarst	A karst term used to describe (a) the result of subsurface removal of limestone taking place beneath permeable loess resulting in a loss of limestone and subsequent slow subsidence of the loess without noticeable surface expression, (b) the initial effects of intergranular solution of rock when there is practically no movement of water from microcavity to microcavity, (c) the karst that develops in chalk beneath a mantle of its residual clay and chert, and (d) pockets in limestone which are filled with terra rossa or other residual material and which may be actively forming, arrested in development, or “inherited”. Because this term has been used for at least four different meanings, it is recommended that it be abandoned [17].
630	cryptozoa	The assemblage of small terrestrial animals found living in darkness beneath stones, logs, bark, etc. Potential colonizers of caves [25].
631	crystal cave	A cave in which much of the surface of the roof, walls, and floor is covered with well-formed mineral crystals [10].
632	crystal pool	In caves a pool, generally having little or no overflow, containing crystals [10].
633	cuesta, hogback	A nonsymetrical ridge due to a gently dipping stratum [16].
634	cueva	(Spanish) Cave, especially one that is horizontal or nearly so [10].
635	cul-de-sac; dead end	A subterranean passage having only one entry [10].
636	cumulative production	The sum total of volumetric discharge of a well since production began [16].
637	cupola	A hemispheric hill of limestone [10]. See also cone karst; cupola karst; mogote; pinnacle karst; tower karst. Synonyms: (French) cupole; (German) Halbkugel.
638	cupola karst	A type of karst topography common in the tropics in which the residual hills rise in hemispherical or dome-capped mounds from intervening depressions or sinkholes [20]. See also cone karst; cupola; pinnacle karst; tower karst. Synonyms: (French) karst à cupules, coupole; (German) Kegelkarst; (Greek) konoidhes karst; (Italian) carsismo con forme residuali a cupola; (Spanish) karst de cupulas; (Turkish) kubbeli karst; (Yugoslavian) kupolni krs̃ (kras).
639	cupula (plural cupulae)	A jellylike rod projecting into the water from a neuromast, part of a fish’s or amphibian’s lateral line system. Vibrations in the water cause the cupula to move, thus setting off nervous impulses that enable the animal to detect nearby movements in the water [23]. [Not to be confused with cupola.]
640	current marking	Shallow asymmetrical hollows, caused by turbulent waterflow, that are distributed in rather regular fashion over limestone surfaces [10]. See also scallop.
641	current meter, current counter	A device used to measure the current velocity directly at a given point [16]. Synonym: ammeter.
642	curtain	1. Sinuous, thin sheet (or sheets) of dripstone formed on the roof or walls of a cave or behind a waterfall [20]. 2. A wavy or folded sheet of flowstone hanging from the roof or projecting from the wall of a cave; often translucent and resonant [10]. See also bacon; blanket; drapery. Related to helictite and speleothem. Synonyms: (French) draperie stalagmitique; (German) Sinterfahne; (Greek) parapetasma stalaktitikon; (Italian) cortina stalattitica; (Russian) zanavesj; (Spanish) bandera, cortina; (Turkish) perde; (Yugoslavian) sigasta zavjesa, sigasta zavesa.
643	curve, backwater	A water surface profile in a stream or channel above a constriction or impoundment [16].
644	curve, concentration	The rising limb on a hydrograph curve [16].
645	curve, desorption	Curve of moisture content verses soil moisture tension [16].
646	curve, drawdown	A plot of drawdown with radial distance from a well [16].
647	curve fitting	The fitting of experimental data points to a theoretical type curve [16].
648	cutter	1. (Tennessee) Solution crevice in limestone underlying residual phosphate deposits. 2. A karren-like groove formed beneath the soil, more commonly referred to as subsoil karren [10]. See also karren.
649	cuttings	Rock chips loosened from the bottom of a borehole by drilling [16].
650	cyanotrichite	A cave mineral — Cu₄Al₂(SO₄)(OH)₁₂·2H₂O [11].
651	cycle	Regular periodic occurrence of an event [16].
652	dam	A structure across a watercourse that impounds water; may be natural or artificial [16].
653	damping	The process of gradually reducing amplitude of a periodic event such as acoustic oscillations in velocity logging [16].
654	dar geçit	See aisle.
655	Darcian velocity; seepage velocity	See specific discharge.
656	Darcy’s law	An empirical law given as: Q = -KA{{dh} OVER {dL}} which states that the average volumetric discharge of flow through a porous medium is directly proportional to the hydraulic gradient assuming that the flow is laminar and inertia can be neglected. Note: Q=discharge, K=hydraulic conductivity, A=cross-sectional area, dh/dL=gradient, and a minus sign is attached as a convention to indicate that flow occurs in the direction of decreasing head [5].
657	Darcy unit	A practical unit for the measure of intrinsic permeability [16].
658	Darcy-Weisbach equation	An empirical equation given as: Q = -A SQRT {{{8Rg} OVER f }{{dh} OVER {dL}}} which states that in contrast to laminar flow, the average volumetric discharge of flow is directly proportional to the square root of the driving force and that the friction loss is equal to the hydraulic head [5]. Note: Q=discharge, A=cross-sectional area, R=hydraulic radius of the conduit, g=gravitational acceleration, f=some friction factor, dh/dL=gradient, and I have attached a negative sign to indicate that ground-water flow occurs in the direction of decreasing head. In most instances, a negative sign is not included because it is not possible to take the square root of a negative number.
659	dark adaptation	A change in the retina of the eye sensitizing it to dim light (the eye “becomes accustomed to the dark”) [25]. Compare light adaptation.
660	dark zone	The part of a cave which daylight does not reach [25].
661	dating of cave sediments	Determination of the age of development of caves is normally impossible. Only the sediments they contain can be dated, and these must necessarily be younger than the containing passage. Geomorphological correlations may allow more accurate dating of the cave erosion. The most useful dating method in current use is based upon a knowledge of the rates of decay of radioactive isotopes of uranium to thorium in stalagmites. This technique allows measurement of ages in material up to 350,000 years old. Dating of stalagmites has confirmed that many cave ages lie beyond this range. Electron spin resonance (ESR) measures the cumulative effects of radiation that are partly a function of time and can give stalagmite ages back to about 900,000 years. Palaeomagnetism may recognize events up to 2 million years old, but a sequence of palaeomagnetically dated sediments is required to allow identification of the actual ages [9].
662	datum plane	A reference level to which topographic or water levels in wells are related [16].
663	daylight hole	A hole in the roof of a cave, reaching the surface [10].
664	dead cave	A dry cave in which all solution and precipitation has ceased [10].
665	dead end	See cul-de-sac.
666	dead water	Standing, stagnant water [16].
667	debris	1. Any material found to have been washed into a cave from some other locality. 2. Coarse rock fragments resulting from erosion and disintegration of bedrock [16].
668	debris karren	These are pinnacles that form in limestones with a thin sheet structure that soon fall into smaller fragments [3]. See also pinnacles.
669	decalcification	Removal by solution of the calcium carbonate constituents from a rock or sediment, leaving a residuum of noncalcareous material[9, 21]. Synonyms: (French) décalcification; (German) Lösungsrückstand (Entkalkung); (Greek) exasvestoses; (Italian) decalcificazione; (Russian) dekaljcifikacija; (Spanish) decalcificación; (Turkish) karbonatını giderme; (Yugoslavian) dekalcifikacijâ.
670	Deckenkarren	(German) Solutional pendant features in cave ceilings [10].
671	declination	The angle from true (or grid) north to magnetic north for a given time and place [25].
672	declogging	The cleaning of clogged well surface or screens [16].
673	decomposers	Living things, chiefly bacteria and fungi, that live by extracting energy from the decaying tissues of dead plants and animals. In the process, they also release simple chemical compounds stored in the dead bodies and make them available once again for use by green plants [23].
674	decoration	Cave features due to secondary precipitation of calcite, aragonite, gypsum, and other rarer minerals.
675	deep percolation	The drainage of soil water downward by gravity below the maximum effective depth of the root zone toward storage in subsurface strata [22].
676	deflocculation	The breakup of flocs of gel structures by use of a thinner [6].
677	deformation	Changing of form, volume, and relative position of rock masses [16].
678	degradation	1. Geological action of wearing down a surface [16]. 2. the process of degrading water quality in an aquifer by the addition of contaminants, either naturally or artificially. 3. The process by which various chemicals are altered to form new chemicals; breakdown.
679	degree of cementation	The degree to which a rock has been solidified due to cementation [16].
680	degree of karstification	The ratio of the volume of openings to the total volume of a soluble massif, expressed as a percentage. It is the sum of the activity indices from the initiation of karstification, and so is normally applied only to carbonate rocks with little or no primary porosity [20]. Related to corrosion and solution. Synonyms: (French) taux de karstification; (German) Ausmaß (Grad) der Verkarstung; (Greek) vathmos karstikiiseos; (Italian) grado di carsificazione; (Spanish) grado de karstificación; (Turkish) karstlaşma derecesi; (Yugoslavian) stupanj krs ̃kog procesa, stopnja zakrasevanja, stepen karstifikacijé.
681	degree of saturation	See percent saturation.
682	delay	The lapse time between signal emission and signal reception in seismic logging [16].
683	delta	A triangular deposit of sediments at the inflow of a river into an ocean or lake [16].
684	demand	The rate of draft from an aquifer or reservoir to meet a certain demand [16].
685	demineralization	The removal of mineral matter from water [16].
686	dendritic	Tree-like pattern [16].
687	dendritic drainage pattern	A drainage pattern in which the streams branch randomly in all directions and at almost any angle, resembling in plan the branching habit of certain trees. It is produced where a consequent stream receives several tributaries which in turn are fed by smaller tributaries. It is an indicative of insequent streams flowing across horizontal and homogeneous strata or complex crystalline rocks offering uniform resistance to erosion. This pattern may form on top of the land surface or below the land surface in karst aquifers with anastomoses forming the smaller tributaries.
688	density	The mass of water per unit volume, usually stated in grams per cubic centimeter (gm/cm3), but may also be measured in pounds per gallon (lb/gal), pounds per cubic foot (lb/ft3), and kilograms per cubic meter (kg/m3.) Density of fresh water is taken to be 1.0.
689	density current	A gravity-induced flow of one current through, over, or under another, owing to density differences. Factors affecting density differences include temperature, salinity, and concentration of suspended particles.
690	denudation	The wearing away of overlying loose rock to top of bedrock [16].
691	denuded karst	Subsoil karst or interstratal karst which has been exposed by erosion of its cover [17]. See also exposed karst; interstratal karst; subsoil karst. Synonyms: (French) karst dénudé; (German) nackter Karst, oberflächlicher Karst; (Greek) apogymnomenon karst; (Italian) carso denudato, carso nudo; (Russian) golij karst, otkritij karst; (Spanish) karst denudado; (Turkish) belirgin karst; (Yugoslavian) ogoljeli krs̃ (krãs), goli krs̃ (krãs), razkriti kras.
692	depletion	The withdrawal of water at a greater rate than replenishment [16].
693	deposition factor	The factor that describes the settling of suspended solids within pore space [16].
694	depression	A small hollow in a surface [16].
695	depression spring	See spring, depression.
696	depth gage	1. Any device used to measure depths such as water level in wells [16]. 2. Specific gage for measuring river stage [16].
697	depth of penetration	In electrical resistivity surveys, it is the depth to which an electrical field penetrates into the subsurface as a function of electrode spacing [16].
698	desalinization	The process of salt removal [16].
699	desander	A device used to separate sand from well water [16].
700	descender	A mechanical device for descending ropes [25].
701	desert	1. Region where precipitation is less than 10 inches per year. 2. Region where the net moisture inflow is too small to support vegetation [16].
702	desiccation	The removal of moisture by evaporation or drying [16].
703	desiccation crack	A crack formed in soil as a result of shrinkage to a drying volume [16].
704	desorption	The reverse process of sorption [22]. See also sorption.
705	detritus	Loose material originating from disintegrated and weathered rock [16].
706	developed section	The result of straightening out a section composed of several parts with differing directions into one common plane. Usually the plane is vertical and the length of the section equals the plan lengths of the passages and chambers comprising it [25].
707	development	The act of repairing damage to the formation caused by drilling procedures and increasing the porosity and permeability of the materials surrounding the intake portion of the well [6].
708	deviation	1. Deflection of a recording from a base line (e.g., the deviation from vertical of a borehole) [16]. 2. Usually a sling of rope or tape attached to a natural anchor at one end and clipped to the rope with a karabiner at the other. Used to avoid rub points on pitches [25]. Synonym: redirection.
709	dew-point	The point at which dew formation starts for given temperature and humidity conditions [16].
710	D-horizon	The zone of bedrock in a soil horizon [16].
711	diagenesis	Post depositional physical and chemical changes in sediment [16].
712	diatomaceous earth	A light-colored, soft, siliceous earth composed of the shells of diatoms, a form of algae. Some deposits are of lake origin but the largest are marine [6].
713	differential water capacity	The absolute value of the rate of change of water content with soil water pressure. The water capacity at a given water content will depend on the particular desorption or adsorption curve employed. Distinction should be made between volumetric and specific water capacity [22].
714	diffuse circulation; diffuse flow	Circulation of ground water in karst aquifers (or other aquifers) under conditions in which all, or almost all, openings (primary and secondary) in the karstified rock intercommunicate and are full of water but have not been selectively enlarged in specific zones by dissolution, and so thus no concentration of ground water occurs in restricted conduits[9, 21]. The ground-water flow is generally slow-moving, may be laminar, and have a uniform discharge and slow response to storms. It is being replaced by the term, slow flow, because significant confusion regarding its usage especially when thought of as in terms of porous-media flow. Synonyms: (French) circulation diffuse; (German) Diffuse Grundwaßerbewegung; (Greek) thiacheomenon ydhor; (Italian) circolazione carsica diffusa; (Spanish) circulación saturada difusa; (Turkish) yaygın dolaşım; (Yugoslavian) difuzno tečenje.
715	diffusion	Process whereby ionic or molecular constituents move under the influence of their kinetic activity in the direction of their concentration gradient [22].
716	diffusion coefficient	See molecular diffusion, coefficient.
717	diffusion, convective	See mechanical dispersion, coefficient.
718	diffusivity, soil water	The hydraulic conductivity divided by the differential water capacity (care being taken to be consistent with units), or the flux of water per unit gradient of moisture content in the absence of other force fields [22].
719	diffusivity, hydraulic	The ratio of transmissivity divided by the storage coefficient or the hydraulic conductivity divided by the specific storage [22].
720	dig	An excavation made to discover or extend a cave or to uncover artefacts or animal bones [25].
721	dike	1. A wall or embankment protecting lowlands from being flooded [16]. 2. A subsurface sheet- like igneous intrusion into bedrock fractures [16].
722	Dinaric Karst	The extensive expanse of karst landscape stretching from Italy, across the whole of southern Slovenia and Croatia, into parts of south-west Bosnia and across Montenegro, ultimately extending into Albania and Greece [9].
723	dip	1. The angle between an inclined bedding plane in a rock sequence and the horizontal. The dip value includes an inclination and a direction and the two components are generally quoted in this order and in the format l0° ENE or 10° towards 025° magnetic (etc.). The dip direction is down the slope. True dip is the maximum dip value of a given bedding plane; other, lesser values, obliquely down the same bedding plane, referred to as apparent dips. The direction at right-angles to the true dip, where the dip value is zero, is known as the strike [9]. 2. Maximum plunge of sloping planar features (e.g bedding, fractures) within a geological formation measured perpendicularly to the strike of the features. See also strike; hade.
724	dipmeter survey	A geophysical borehole logging method where the dip of the penetrated strata is measured [16].
725	diphenyl brilliant flavine 7GFF, direct yellow 96	A yellowish dye initially developed to color tennis balls and subsequently shown to be useful in environmental tracing studies. Dye type: Stilbene. See also fluorescent dyes.
726	discharge	The volumetric flow of water through a given cross section [16].
727	discharge area	An area in which ground water is discharged to the land surface, surface water, or atmosphere [22].
728	discharge, evaporation	The direct discharge of ground water to the atmosphere by evaporation [16].
729	discharge, hydraulic	The discharge of ground water through springs or wells [16].
730	discharge, maximum	The maximum discharge of a river or spring during high flow conditions [16].
731	discharge, natural	The discharge of water into surface water bodies or springflow [16].
732	discharge hydrograph	A graph showing the discharge of water as a function of time [16].
733	discharge pipe	A pipe through which a pump discharges [16].
734	discharge pressure	The pressure at which a certain discharge takes place [16].
735	discharge velocity	The rate of discharge of water through a porous medium per unit of total area perpendicular to the direction of flow.
736	disconformity	A geological unconformity between parallel beds, often with some series missing [16].
737	discontinuity	1. A point where a mathematical function becomes nondefined [16]. 2. An unconformity in which the bedding planes above and below the break are basically parallel, indicating a significant hiatus in the orderly sequence of sedimentary rocks. 3. A surface at which seismic-wave velocities abruptly change.
738	discontinuity surface	Any surface across which some property for a rock mass is discontinuous. This includes fracture surfaces, weakness planes, and bedding planes but the term should not be restricted only to mechanical continuity.
739	dispersion	The spreading and mixing of chemical constituents in ground water caused by diffusion and mixing due to microscopic variations in velocities within and between pores [6].
740	dispersion coefficient	1. A measure of the spreading of a flowing substance due to the nature of the porous medium, with its interconnected channels distributed at random in all directions [22]. 2. The sum of the coefficients of mechanical dispersion and molecular diffusion in a porous medium [22].
741	dispersion, longitudinal	Process whereby some of the water molecules and solute molecules travel more rapidly than the average linear velocity and some travel more slowly which results in spreading of the solute in the direction of the bulk flow [22].
742	dispersion, mechanical	See mechanical dispersion.
743	dispersion, transverse	Spreading of the solute in directions perpendicular to the bulk flow [22].
744	dispersion zone	A zone of intermixing in miscible flow or in sea water encroachment. See also transition zone [16].
745	dispersivity	A geometric property of a porous medium which determines the dispersion characteristics of the medium by relating the components of pore velocity to the dispersion coefficient [22].
746	displacement	1. The process of replacing one fluid in a porous medium by another [16]. 2. A change in position of a material point. See also miscible displacement.
747	disposal well	A well used for the disposal of waste into a subsurface stratum. See also injection well [22].
748	dissociation	A chemical process that causes a molecule to split into simpler groups of atoms, or ions. For example, the water molecule (H₂O) breaks down spontaneously into H+ and OH– ions [6].
749	dissolution	See solution.
750	dissolution of limestone	The solubility of calcite (and hence of limestone) in pure water is very low, but is vastly increased in the presence of carbon dioxide. This gas, dissolved in the water to produce carbonic acid, permits dissociation of calcium carbonate, and dissolution rates and loads are therefore directly related to carbon dioxide content. This accounts for the importance to limestone dissolution of plant growth; soil water contains greatly more carbon dioxide than stream waters. Further dissolution occurs due to mixing of saturated waters of different carbon dioxide content (see Mischungskorrosion), because of a non-linear relationship between carbonate saturation and carbon dioxide content. This process is of major significance to continued dissolution within the phreas. Cold water can dissolve more carbon dioxide but, with respect to cave development, this climatic factor is overwhelmed by the higher organic activity producing more carbon dioxide in warmer environments. Loss of carbon dioxide, by diffusion into open air, causes water to precipitate calcite as speleothems. Limestone dissolution may also be achieved by organic acids or by strong acids, particularly sulphuric acid, though such effects are normally far less than that of carbon dioxide. Strong acid dissolution is probably involved in the inception of most underground drainage. Dissolution by sulphuric acid formed by oxidation of sulfide minerals or gases may be a major cave-forming process in some regions, and was largely responsible for the enlargement of Carlsbad Caverns and Lechuguilla Cave, New Mexico [9].
751	dissolution zone	A laterally extensive zone where extensive dissolution of bedrock has occurred.
752	distortion	A change in shape of a solid body.
753	distribution coefficient	The quantity of the solute, chemical, or radionuclide sorbed by the solid per unit weight of solid divided by the quantity dissolved in the water per unit volume of water [22].
754	distribution, frequency	Distribution of the number of occurrences of a variate.
755	disturbance	In geology, any change of the original position of rocks by folding [16].
756	disturbed sample	A sample disturbed with respect to its original mode of packing and sedimentation (e.g., a drill core) [16].
757	divide	1. A line connecting the highest topographic elevations or ground-water crests that separate one drainage basin from another [16]. 2. A ridge in the water table or potentiometric surface from which the ground water represented by that surface moves away in both directions. Water in other aquifers above or below, and even in the lower part of the same aquifer, may have a potentiometric surface lacking the ridge, and so may flow past the divide. See also ground-water divide; water-table divide. Synonyms: ground-water divide; ground-water ridge; water-table divide. 3. (a) The line of separation, or the ridge, summit, or narrow tract of high ground, marking the boundary between two adjacent drainage basins or dividing the surface waters that flow naturally in one direction from those that flow in the opposite direction; the line forming the rim of or enclosing a drainage basin; a line across which no water flows. 3. (b) A tract of relatively high ground between two streams; a line that follows the summit of an interfluve [1]. See also drainage divide.
758	DNAPL	Abbreviation for dense nonaqueous phase liquid. Liquids falling into this category have specific gravities greater than water (the specific gravity for water is usually taken to be one), are relatively immiscible with water, and tend to migrate downwards through the vadose and phreatic zones in a relatively unimpeded manner. See also LNAPL; immiscible; NAPL.
759	dog-tooth crystal; dog-tooth spar	A variety of calcite in the form of sharp-pointed crystals [10].
760	doline; sinkhole	A basin- or funnel-shaped hollow in limestone, ranging in diameter from a few meters up to a kilometer and in depth from a few to several hundred meters. Some dolines are gentle grassy hollows; others are rocky cliff-bounded basins. A distinction may be made by direct solution of the limestone surface zone, (solution dolines), and those formed by collapse over a cave, (collapse dolines), but it is generally not possible to establish the origin of individual examples [10]. Solutional enlargement is either circular in plan, if there is one dominant vertical joint, or otherwise irregular if there are several and can achieve dimensions of up to 1,000 meters in diameter and 100 meters deep. Where a karst bedrock is covered by superficial deposits, solutional enlargement permits the latter to subside into vertical fissures, creating subsidence cones or alluvial dolines, whose slopes are unstable because of the unconsolidated nature of the surface material. The bedrock remains covered in the first instance. Dolines are also formed by the large-scale subsidence caused by cave roof-collapse of near-surface caverns; in this instance, the collapse doline, the sides are cliff-like and the floor composed of the irregular blocks from the fragmented roof. Cave roof-collapse is considered a relatively rare phenomenon. Closed depressions receiving a stream are known as swallow holes or stream sinks. A doline which is largely dependent upon snow for solution-enlargement is known as a kotlici or Schneedoline [19]. In America most dolines are referred to as sinks or sinkholes. See also jama; pit; ponor; sink, sinkhole; stream sink; swallet; swallow hole; sumidero. Synonyms: (French) doline; (German) Dolinen, Karsttrichter; (Greek) tholene; (Italian) dolina, pozzo naturale; (Russian) karstovaja voronka, karstovaja kotlovina; (Spanish) dolina; (Turkish) düden, kokurdan, huni; (Yugoslavian) vrtača, ponikva, dolac, do, duliba, kotlič, konta.
761	doline karst	Karst dominated by closed depressions, chiefly dolines, perforating a simple surface [25].
762	doline lake	A small karst lake occupying a doline or closed depression in limestone. The term implies that the doline is at or near the ground-water table and in hydrological continuity with it, or that the base of the doline is sealed with an impermeable layer such as clay [20]. See also sinkhole pond. Synonyms: (French) lac de doline; (German) Dolinensee; (Greek) limni dholina; (Italian) lago di dolina, lago carsico; (Russian) karstovoe ozero; (Spanish) dolina laguna, torca laguna; (Turkish) obruk gölü; (Yugoslavian) krs ̃ko jezero, kras ̃ko jezero.
763	dolomite	1. The pure mineral dolomite has the composition CaMg(CO₃)₂ and has properties very similar to those of calcite. The rock dolomite consists mainly of the mineral dolomite, with subordinate calcite, and has properties very similar to those of limestone. The natural dissolution of dolomite is generally slower than that of limestone. Hence, dolomite karst is generally less well developed than limestone karst, though exceptions do occur in areas such as north-west Canada. Large, deep caves can form in dolomite, as in the Rand of South Africa [9]. 2. A mineral composed of calcium magnesium carbonate, CaMg(CO₃)₂. 2. Rock chiefly composed of the mineral dolomite [10]. Also called dolostone.
764	dolomitic limestone	A limestone containing a significant proportion of the mineral dolomite but in which calcite is more abundant (e.g. 10–45% dolomite, 90–55% calcite). Many dolomitic limestones originate as calcite limestone that is subsequently affected by magnesium-rich water that replaces part of the calcite with dolomite [9].
765	dolomitic flour (sand)	A loose mealy rock or residuum, produced by the disintegration of dolomitic limestones under the processes of karstification [20]. Synonyms: (French) sable dolomitique; (German) Dolomitsand, Dolomitasche; (Greek) dholomitikon alevron; (Spanish) arena dolomítica; (Turkish) dolomit kumu; (Yugoslavian) dolomitni pijesak, d. pesak, d. pesek.
766	dolomitization	The process whereby limestone becomes dolomite by the substitution of magnesium carbonate for part of the original calcium carbonate [10].
767	domain	A biological region of the earth’s crust [25].
768	dome	1. A high shaft in a room or passage formed by solution [13]. 2. A large hemispheroidal hollow in the roof of a cave,formed by the breakdown and/or salt weathering, generally in mechanically weak rocks, which prevents bedding and joints dominating the form [25]. See also dome pit.
769	dome pit	1. American term defined by Davis (1930) “Mammoth Cave possesses several extraordinary vertical cavities of which the arched tops are called domes and the deep bottoms are called pits. The combined name, dome pits, is here used for them”. 2. A deep shaft in a cave, intersected by a passage at or near its mid-section [20]. See aven. Synonyms: (French) évorsion, marmite inversée; (German) Deckenkolk; (Greek) vathís lákkos me thólon; (Italian) marmitta inversa; (Spanish) marmita inversa; (Turkish) kemerli obruk.
770	donga	In the Nullarbor Plain, Australia, a shallow, closed depression, several meters deep and hundreds of meters across, with a flat clay-loam floor and very gentle slopes [25].
771	double brake bars	A rappel device used by cavers that consists of two carabiners with a brake bar on each and connected together with another carabiner or a metal ring [13].
772	downwarping	A down bending of stratum to form a depression or syncline [16].
773	drag	The resistance force of flowing fluid on a solid boundary [16].
774	drainage area	A horizontal projection of an area drained by a particular river system [16].
775	drainage basin	The land area from which surface runoff drains into a stream channel or system of stream channels, or to a lake, reservoir, or other body of water [6]. In a karst setting, subsurface drainage (internal drainage) may have boundaries defined on the basis of comprehensive ground- water tracing studies. See also ground-water basin.
776	drainage density	A ratio of total channel segments lengths cumulated for all orders to basin area [16].
777	drainage ditch	A small channel through which surface water can drain [16].
778	drainage divide	The rim of a drainage basin [16]. See also divide; ground-water divide; water-table divide.
779	drainage network	A system of streams and rivers draining a given basin [16].
780	drainage pattern	A geometric arrangement of stream segments in a drainage system [16].
781	drainage ratio	A ratio of runoff to precipitation [16].
782	drainage system	A network of streams and tributaries [16].
783	drainage well	1. A well installed to drain surface water, storm water, or treated waste water into underground strata [22]. 2. A water well constructed to remove subsurface water or to reduce a hydrogeologic unit’s potentiometric surface [22].
784	drain tile; french drain	A porous pipe used for collection of excess ground water [16].
785	drapery	A thin sheet of dripstone, equivalent to curtain [10]. See also bacon; blanket; curtain.
786	draw	A natural depression or small valley [16].
787	drawdown	1. The vertical distance the water elevation is lowered or the reduction of the pressure head due to the removal of water [22]. 2. The decline in potentiometric surface at a point caused by the withdrawal of water from a hydrogeologic unit [22].
788	drawdown curve	A plot of drawdown with radial distance from a well [16].
789	driphole	1. Hole in rock or clay produced by fast-dripping water. 2. Hollow space surrounded by precipitated material, such as the bottom of a stalactite [10].
790	dripline	A line on the ground at a cave entrance formed by drips from the rock above. Useful in cave survey to define the beginning of the cave [25].
791	dripstone	Calcium carbonate deposited from water dripping from the ceiling or wall of a cave or from the overhanging edge of a rock shelter; commonly refers to the rock in stalactites, stalagmites, and other similar speleothems; in some places composed of aragonite or gypsum [10]. Synonyms: (French) concrétions; (German) Tropfstein, Stalagmit, Stalaktit; (Greek) stalaktitis, stalagmitis; (Italian) concrezione; (Russian) kapeljnik; (Spanish) concreción (estalagmitjca o estalactítica); (Turkish) damlataşı; (Yugoslavian) sige, smugori. See also flowstone.
792	drowned karst	Karst topography that is submerged by a change in sea level or lake level. Synonym: karst noyé. See also subaqueous karst.
793	drowned spring	See spring, drowned.
794	drought	A period of moisture deficiency and absence of water for plant growth [16].
795	dry cave	A cave without a running stream [10]. See also dead cave.
796	dry hole	A hole not obtaining any production. A non-producing well [16].
797	dry valley	1. Valley that lacks a permanent surface stream. Dry valleys are common on carbonate rocks with good primary permeability and occur on other permeable rocks such as sandstone. Dry valleys on cavernous limestone were formed when streams flowed on the surface, either before secondary permeability and cave systems developed, or when caves were blocked by ground ice in periglacial climates. The valleys became dry when underground drains formed or were re-opened, capturing first part and then all of the surface drainage [9]. 2. A valley that lacks a surface water channel; common in the chalk of southern England [10]. 3. Elongated recesses and valleys at the bottom of which are dolines, jamas and caves. 4. A valley form of fluvial or periglacial origin in which surface drainage is intermittent or totally absent. Fossil, usually with steep scree slopes, it is variously identifiable as a product of nival processes or higher water tables subsequently lowered by allogenic valley [19]. Synonyms: (French) vallée sèche; (German) Trockental; (Greek) xera kilas; (Italian) valle morta, valle asciutta; (Russian) suhaja dolina; (Spanish) valle seco; (Turkish) kuru vadi; (Yugoslavian) suha dolina.
798	duck; duck-under	1. A place where water reaches the cave roof for a short distance and can be passed by quick submergence without swimming. 2. In cave diving, a longer stretch of passage where the water is so close to the roof that crawling or swimming beneath the water surface is needed to pass [10].
799	dug well	A hand excavated well [16].
800	dune limestone	(Australian) See eolian calcarenite.
801	Dupuit’s assumption	A simplifying assumption for the solution of a free surface well flow problem [16] (e.g. a water-table aquifer.) It is based on the assumption that the slope of the phreatic surface is negligibly small so that the equipotential lines are vertical and flow is essentially horizontal.
802	duration curve	A cumulative frequency curve of a continuous time series of hydrologic parameters [16].
803	Durchgangshöhle	(German) See through cave.
804	dye gaging	See tracer gaging.
805	dye test	Determination of direction and rate of flow of streams by marking them with dye at the infiltration area and then identifying and timing the reappearance of color at lower-lying springs, in river beds and elsewhere in a cave system [20]. Synonyms: (French) coloration; (German) Färbung, Färbversuch; (Greek) chrostike ichnithetesis; (Italian) tracciamento con colorante; (Russian) method krasjascih, indikatorov; (Spanish) coloración; (Turkish) boya deneyi; (Yugoslavian) bojenje, barvanje. See also tracer.
806	dynamic phreas	See phreas, dynamic.
807	dynamic similarity	A scaling procedure of model and prototype where the relationship of dynamic parameters is retained [16].
808	dynamometer	A device used to measure the momentum force of a stream velocity [16].
809	Easting	1. The distance of a point east of the point of origin of the grid of a map or some abbreviation of it [25]. 2. The west-east component of a survey leg, or of a series of legs or of a complete traverse; east is positive and west is negative [25].
810	ebb-and-flow spring; ebbing-and-flowing well	See spring, ebb-and-flow.
811	eccentric	Adjective or noun implying abnormal shape in speleothems, such as helictites [10].
812	eccentric well	A well that is not in the center of the radius of influence [16].
813	ecology	The scientific study of the relationships of living things to one another and to their environment. A scientist who studies these relationships is an ecologist [23].
814	eddy	A non-laminar circulation of fluid at boundaries of flow separation [16].
815	effective abstractions	The difference between total precipitation and effective precipitation [16].
816	effective diameter	A 10 percentile size (i.e. 10% diameter smaller than this diameter) [16].
817	effective hydraulic conductivity	See hydraulic conductivity, effective.
818	effective porosity	See porosity, effective.
819	effective precipitation	That part of precipitation that contributes entirely to direct runoff.
820	effective rainfall	Effective precipitation when only rainfall is involved [16].
821	effective size	The 90%-retained size of a sediment as determined from a grain-size analysis; therefore, 10% of the sediment is finer and 90% coarser [6].
822	effluent	1. The discharge of water or other fluids from a spring. 2. A waste liquid discharge from a manufacturing or treatment process, in its natural state or partially or completely treated, that discharges into the environment [6].
823	effluent cave	See outflow cave.
824	effluent stream	See gaining stream.
825	elastic limit	The point on a stress/strain curve at which transition from elastic to inelastic behavior takes place.
826	elastic properties	The properties describing deformation of a solid [16].
827	elasticity	The property of a material that allows the material to return to its original form or condition after the applied force has been removed.
828	electric lamp	As used in caving, generally a helmet-mounted headpiece (bulb, reflector, and lens) with a wire running to a battery carried elsewhere on the person [13].
829	electro-chemical gaging	Flow measurement based on electric detection of electrolyte tracer flow [16].
830	electrolyte	A chemical which dissociates into positive and negative ions when dissolved in water, increasing the electrical conductivity [6].
831	elutriation	A washing process by decantation with water [16].
832	embankment	A natural or artificial lateral boundary of a river [16].
833	embryo	A developing individual before its birth or hatching [23].
834	emergence	A general term for the outflowing water, for the opening or for the area of outflow of a karst spring; includes exsurgence and resurgence [20]. Synonyms: (French) émergence; (German) Ausfluβtelle, Karstquelle; (Greek) pigházon ýthor (or kephalari); (Italian) risorgenza; (Russian) vihod karstovih vod; (Spanish) fuente, manantial, surgencia; (Turkish) yüzeye erişim; (Yugoslavian) krško vrelo, krs ̃ki izvor, obrh. See also exsurgence; resurgence; rise.
835	encroachment	1. The landward advancement of saline waters into coastal aquifers [16]. 2. The displacement of clean water by pollutants [16].
836	end effect	A disturbance introduced by the inflow and outflow sections in a flow experiment [16].
837	endellite	A cave mineral — Al₂Si₂O₅(OH)₄·2H₂O [11].
838	endogean	Pertaining to the domain immediately beneath the ground surface, i.e., in the soil or plant litter [25]. See also endogenic, epigean, hypogean.
839	endogenic	1. Pertaining to, or living in, the zone immediately beneath the earth’s surface [9]. 2. Pertaining to geological process originating within the earth [16]. See also endogean, epigean, hypogean.
840	endokarst	The part of a vertically layered karst system that is beneath the surface. Endokarst includes the full spectrum of underground voids and the dissolutional features that are present on the rock surfaces surrounding them [9]. See also exokarst.
841	energy head	Hydraulic head plus velocity head [16].
842	enthalpy	Heat content [16].
843	entrance capacity	The property of a soil to allow water to infiltrate (the maximum value of this property) [16].
844	entrenchment	Erosion of an existing cave floor by a freely flowing stream to form a canyon passage that is commonly narrower than the original passage. Where the stream entrenches an originally tubular phreatic passage a characteristic keyhole shaped profile develops. Also known as vadose entrenchment or incision [9].
845	entropy	The degree of thermodynamic disorder [16].
846	environment	All the external conditions surrounding a living thing [23].
847	eolian calcarenite	A terrestrial limestone formed by the cementation by carbonates of calcareous coastal dune sand. Often shorted to eolianite. Synonym: dune-limestone; aeolianite. Compare beachrock.
848	eolian deposit	Sediment material deposited by wind action [16].
849	ephemeral stream	A stream flowing only in direct response to precipitation [16].
850	epigean	Pertaining to, or living on, the surface of the earth. See endogean and hypogean.
851	epigeum	The surface environment [23].
852	epikarst; epikarst zone	A relatively thick (the thickness may vary significantly, but 15 to 30 meters thick is a good generalization) portion of bedrock that extends from the base of the soil zone and is characterized by extreme fracturing and enhanced solution. It is separated from the phreatic zone by an inactive, relatively waterless interval of bedrock that is locally breached by vadose percolation. Significant water storage and transport are known to occur in this zone. Synonym: subcutaneous zone.
853	epikarstic flow	See subcutaneous flow.
854	epilimnion	Upper layer of stratified water [16].
855	epiphreas, epiphreatic zone	The zone in a cave system, immediately above the phreatic zone, affected morphologically and hydrologically by floods too large for the cave to absorb at once [10].
856	epsomite	A cave mineral — MgSO₄·7H₂O [11].
857	equation of hydrologic equilibrium	A mass balance for a ground-water basin [16].
858	equipotential line or surface	1. A contour line on the potentiometric surface along which the pressure head of ground water in the aquifer is the same. Fluid flow is normal to these lines in the direction of decreasing fluid potential [6]. 2. Line (or surface) along which the potential is constant [22].
859	equivalent per million	The number of equivalent weights in a million parts per weight solution [16].
860	erodible	Susceptible to erosion [16].
861	erosion	1. The general process or group of processes whereby the materials of the Earth’s crust are moved from one place to another by running water (including rainfall), waves and currents, glacier ice, or wind [6]. 2. The sequence of processes of disintegration and transportation of rock material [16].
862	erosion surface	The land surface resulting from the action of erosion [16].
863	erosiveness	The capacity to erode [16].
864	escarpment	A steep slope, often the result of faulting [16].
865	estavelle	(French) An intermittent resurgence or exsurgence, active only in wet seasons. May act alternatively as a swallow hole and as a rising according to ground-water conditions [10]. Opening in karstic terrane which acts as a discharge spring during high potentiometric surface and as a swallet during low potentiometric surface. Sea estavelles are known to exist [20]. Synonyms: (French) estavelle; (German) Estavelle; (Greek) estavella; (Italian) estavella; (Russian) estavella; (Spanish) estavela; (Turkish) su batar çıkarı; (Yugoslavian) estavela, ponor-rigalo.
866	esker	A stratified fluvio-glacial deposit in the form of a winding ridge [16].
867	etched pothole	See solution pan.
868	estuary	The lower course of a river discharging into the sea and subject to tidal currents [16].
869	evaporate	A sedimentary rock formed by evaporation and precipitation of saline waters [16].
870	evaporation	The changing or water from the liquid or solid states into the gaseous state through heat exchange [16].
871	evaporation loss	The loss of precipitated water that is discharged to the atmosphere by evaporation [16].
872	evaporation opportunity	The amount of water made available for discharge into the atmosphere [16].
873	evaporation pan	An open tank used to measure evaporation [16].
874	evaporation reduction	The rate control of escape of water vapor from an open surface [16].
875	evaporation suppression	The complete prevention of evaporation by mechanical or physico- chemical means (e.g., monomolecular layer) [16].
876	evaporite	Rock formed by precipitation of minerals from evaporating water, usually from sea water. As sea water evaporates the least soluble mineral contents precipitate first; these include calcium carbonate that is deposited as fine-grained limestone. If evaporation continues, first gypsum, then halite and finally a number of other sulfates and chlorides are deposited [9].
877	evaporativity	Evaporative power [16].
878	evapotranspiration	1. The combined loss of water from a given area and during a specified period of time, by evaporation from the land and transpiration from plants [22]. 2. The return of water in vapor form to the atmosphere through the combined actions of evaporation, plant transpiration, and sublimation [16].
879	evolution	The process of natural consecutive modification in the inherited makeup of living things; the process. by which modern plants and animals have arisen from forms that lived in the past [23]. See also mutation.
880	evorsion	Mechanical erosion by whirling water that may carry sand and gravel; pothole erosion [10]. Mechanical erosion by rotating or whirling water carrying sand, gravel, cobbles, or boulders in suspension or as bedload [20]. Synonyms: (French) évorsion; (German) (Auswaschung), Auskolkung; (Greek) mihanikí diávrosis; (Italian) evorsione; (Spanish) evorsión; (Turkish) dev kazanı aşındırması; (Yugoslavian) vrtložna erozija.
881	exchange capacity	1. The amount of exchangeable ions measured in moles of ion change per kilogram of solid material at a given pH. Synonymous with ion exchange capacity [22]. 2. The total ionic charge of the adsorption complex active in the adsorption of ions [22]. See also cation-exchange capacity.
882	exhumed karst	A karstic outcrop which has been exposed by the erosion of an allochthonous cover; there is an implication that karstification (partial or complete) had preceded the removal of the cover [20]. Mantled karst or buried karst which has been divested of its cover. It is the re- exposed portion of a former landscape [17]. See also buried karst; exposed karst; mantled karst. Synonyms: (French) karst dénudé; (German) wiederaufgedeckter Karst; (Greek) gymnothen karst; (Italian) carso riesumato; (Spanish) karst exhumado; (Turkish) açık karst; (Yugoslavian) ogoljeli krš (kras).
883	exogenic	Pertaining to processes on or near the surface of the earth [16].
884	exokarst	All features that may be found on a surface karst landscape, ranging in size between tiny karren forms and extensive projes, belong to the exokarst [9]. See also endokarst.
885	exoskeleton	An external skeleton. The hard body covering or shell of most invertebrate animals, including insects, crayfish, and millipedes [23].
886	experimental basin	A basin chosen for the thorough study of hydrological phenomena [16].
887	exposed karst	A general term for bare karstic rocks outcropping at the surface of the ground. It embraces karst areas without any initial cover (naked karst) or exposed by erosion of the residuum and soil (denuded karst) or of the allochthonous cover (exhumed karst) [20]. Karst topography in which cover is absent [17]. Synonyms: (French) karst exposé; (German) nackter Karst, oberflächlicher Karst, wiederaufgedeckter Karst; (Greek) akalypton karst; (Italian) carso denudato; (Russian) golij karst, otkritij karst; (Spanish) karst subaéro; (Turkish) belirgin karst; (Yugoslavian) ljuti krš. See also denuded karst; exhumed karst; naked karst.
888	extensometer	An instrument used for measuring vertical deformation of fine-grained beds in the subsoil under stress. Vertical extensometers commonly are installed when land subsidence follows ground-water withdrawal. Extensometers also are used to measure small horizontal displacements [21].
889	external loads	External loads causing water level fluctuations in wells.
890	exsurgence	1. A term used to explain the re-emergence at the surface, as a stream, of meteoric water which has fallen entirely upon and percolated through a calcareous massif [19]. 2. A spring or seep in karstic terrane not clearly connected with swallets a higher level. Synonyms: (French) exsurgence; (German) Karstquelle, Austrittßtelle; (Greek) karstiki pighi; (Italian) risorgente carsica; (Russian) karstovij istoćnik; (Spanish) exsurgencia; (Turkish) yüzeyde blirme; (Yugoslavian) vrelo, obrh. See also emergence; resurgence.
891	fabric	The orientation in space of the elements composing a rock substance.
892	facet	See scallop.
893	facies	The lithologic appearance of a rock [16].
894	facies change	The change in appearance that occurs when one lithologic unit ends and a new one is encountered.
895	failure	In rocks, failure means exceeding of the maximum strength of a rock or exceeding the stress or strain requirement of a specific design.
896	fall	The gross slope of a river [16].
897	false floor	A remnant of a sheet of flowstone, originally deposited on clastic sediments that were subsequently washed out from beneath. False floors may survive as a complete bridge between passage walls or just as projecting ledges. They may be thin and easily broken or thick and very strong [9].
898	farangothes ipoyios thiavasis	See aisle.
899	fathometer	A water depth measuring device [16].
900	fault	1. A fracture in the earth’s crust, across which relative rock movement has taken place, or continues to take place. Fault planes commonly guide vertical or sub-vertical shafts in caves, as well as guiding sub-horizontal or oblique passages within the confines of the fault plane [9]. 2. A fracture or fracture zone along which there has been displacement of the two sides relative to one another parallel to the fracture [6]. This displacement may be of a few centimeters or many kilometers. See also joint fault set; joint fault system.
901	fault breccia	The assemblage of broken rock fragments frequently found along faults. The fragments may vary in size from inches to feet.
902	fault cave	A cave developed along a fault or fault zone [10].
903	fault gouge	A clay-like material occurring between the walls of a fault as a result of the movement along the fault surfaces.
904	fault line	The intersection of a fault with the surface of the earth or any other plane of reference [16].
905	fault plane	A plane on which dislocation and relative movement has taken place [16].
906	fault scarp	An elevation formed by movement of blocks along a fault plane [16].
907	fault zone	A zone with numerous small parallel faults [16].
908	feeding tube	In karst terrane, a more or less straight and waterbearing underground gallery of regular cross-section. Synonyms: (French) tunnel; (German) Stro ̌mungsrohr, Karstgerinne; (Greek) karstikos ypoyios agogos; (Spanish) tubo; (Turkish) akarsu mecrası; (Yugoslavian) vodonosni rov. See also stream tube.
909	feldspars	A very common group of rock forming minerals [16].
910	fengcong; fengcong karst	(Chinese) 1. A karst, conspicuous in China, that is identified by its clustered limestone hills. Fengcong (pronounced “fungston”), which translates as “peak cluster”, is a mature karst normally developed during long uninterrupted periods of rapid dissolution in wet tropical environments with high levels of biogenic soil carbon dioxide. The Chinese classify karst by the hill or peak density, in contrast to the Western classification by hill shape. Fencong is almost the equivalent of cone karst; its closely packed hills are conical rather than hemispherical, with intervening dolines and disjointed valleys. The major occurrences are in Guizhou and Guangxi, in southern China. Some cones in Guangxi are so steep that they have been termed fengcong tower karst, but this concept is best avoided [9]. 2. Tower karst characterized as peak cluster because the individual karst towers appear to be grouped together in clusters. Closed depression among the peaks are common [4]. See also fenglin; fungling; mogote; tower karst.
911	fenglin; fenglin karst	(Chinese) 1. A karst, conspicuous in China, that is identified by its isolated limestone hills. Fenglin (pronounced “funglin”) translates from Chinese as “peak forest”, and is distinguished from fengcong. Both fenglin and fengcong are mature karst normally only developed by long uninterrupted periods of rapid dissolution in wet tropical environments with high levels of biogenic soil carbon dioxide. The Chinese classify karst by the hill or peak density, in contrast to the Western classification by hill shape. Fenglin is therefore almost the equivalent of tower karst; its hills have very steep or vertical walls, and may have a height/width ratio greater than four. The limestone hills rise above level, alluviated plains, and the finest fenglin karst around Yangshuo, Guangxi, in southern China, is one of the world’s most dramatic landscapes. The classification by hill density means that low residual cones scattered across a plain are also referred to as fenglin by the Chinese [9]. 2. Tower karst characterized as peak forest because the individual towers appear as isolated groups on a plain. Dry valley networks separate individual towers [4]. See also fengcong; fungling; mogote; tower karst.
912	ferghanite	A cave mineral — U₃(VO₄)₂·6H₂O [11].
913	ferric oxide	Rust; hematite (Fe₂O₃) [16].
914	ferrito zone	Zone of iron oxide accumulation in soil under humid climate conditions [16].
915	Fickian diffusion	The spreading of solutes from regions of highest to regions of lower concentrations caused by the concentration gradient. In slow moving ground water, this is the dominant mixing process [22].
916	fissure	Any discontinuity within the rock mass that is either initially open or capable of being opened by dissolution to provide a route for water movement. Fissures in this sense, applied generally in karst, therefore include the primary sedimentary bedding planes as well as tectonic faults and joints. More specifically, the term has been used to describe voids with average dimensions from 10 to 100mm [9]. See also conduit; fracture.
917	field capacity; field moisture capacity	See specific retention.
918	field survey	Measurements taken in the field [16].
919	field test	A test run in the field under normal field conditions [16].
920	field velocity of ground water	Actual interstitial velocity of ground water [16].
921	fill terrace	An elevated valley surface formed by aggregation [16].
922	fine gravel	Rock aggregates of 1–2 mm diameter [16].
923	fine sand	A silicon dioxide material with a grain diameter of 0.1– 0.25 mm [16].
924	finite difference method	A numerical method used to approximate the solution of partial differential equations [16].
925	finite element method	A numerical method used to approximate the solution of partial differential equations.
926	firn	Compacted granular snow [16].
927	firstkarren	(Austrian) See Rillenkarren.
928	fissure	An open joint or crack in rocks [16].
929	fissure cave	A narrow vertical cave or cave passage along a fissure. Fissures widen out to become wells or vertical shafts [10]. See also vertical shaft.
930	Flachkarren	(German) See clint.
931	flank	A limb of a fold [16].
932	flash flood	A relatively short but very intense flood [16].
933	flattener	A cave passage, which though wide, is so low that movement is only possible in a prone position [10]. See also crawl.
934	flexure	A bend in a stratum with one flank or limb only [16].
935	flint	A concretionary form of silica, similar to chert, that occurs in chalk as tabular sheets and layers of irregularly shaped nodules. Being very hard and relatively insoluble, flint tends to stand out from chalk cliffs. Flint-rich horizons may also influencer the inception of bedding-related dissoluational conduits in chalk [9].
936	float gage	A device that indicates or records water levels with a float [16].
937	floating pan	An evaporation pan floating in a water body with drum floats [16].
938	floe calcite	Very thin film of pure calcium carbonate floating on the surface of a subterranean pool of very calm water [10].
939	flood	A high river flow overtopping banks.
940	flood crest	The peak of a flood wave [16].
941	flooding method	A recharge method by flooding a recharge area [16].
942	floodmarks	The marks left on fixed objects by flood waters [16].
943	flood plain	The surface or strip of relatively smooth land adjacent to a river channel, constructed by the present river and covered with water when the river overflows its banks. It is built of alluvium carried by the river during floods and deposited in the sluggish water beyond the influence of the swiftest current [6].
944	flood profile	A continuous line representing the water surface for a given rate of flow [16].
945	flood water	Water that has overflowed its confines; the water of a flood [1].
946	flood-water zone	See epiphreas.
947	flood wave	A rise in the stage of a stream that culminates in a crest before receding [1].
948	floor pocket	See pocket.
949	flow, base	See base flow.
950	flow, creep	Flow with a creeping motion where inertial terms have been dropped [16].
951	flow, critical	See critical flow.
952	flow duration curve	A curve of cumulative streamflow versus the corresponding per cent of time [16].
953	flow gage	A gage used to measure flow rate [16]. See also gage.
954	flow-mass curve	1. A mass curve with runoff discharge as a hydrologic quantity [16]. 2. The integral of the curve of a hydrograph [16].
955	flow line	The general path that a particle of water follows under laminar flow conditions [22]. Flow lines are usually drawn perpendicular to equipotential lines. See also equipotential lines.
956	flow net	1. A graphical representation of flow lines and equipotential lines for two-dimensional, steady-state ground-water flow [22]. 2. A net of orthogonal streamlines and equipotential lines applied in the graphical solution of Laplace’s equation [16].
957	flow path	The subsurface course a water molecule or solute would follow in a given ground-water velocity field.
958	flow rate	Volumetric rate of flow [16].
959	flow, steady	A characteristic of a flow system where the magnitude and direction of specific discharge are constant in time at any point [22]. See also flow, unsteady.
960	flow, uniform	A characteristic of a flow system where specific discharge has the same magnitude and direction at any point [22].
961	flow, unsteady	A characteristic of a flow system where the magnitude and/or direction of the specific discharge changes with time. Synonymous with nonsteady flow. See also flow, steady.
962	flow velocity	See specific discharge.
963	flower	A cave flower is a group of crystals, commonly of gypsum or mirabilite, that grow by accretion at their bases on a cave wall. As the crystals grow, curve and splay, their form mimics that of a flower [9].
964	flowing artesian well	A well with its potentiometric surface above the ground surface [16].
965	flowmeter	An instrument for measuring volumetric flowrate [16].
966	flowstone	Deposits of calcium carbonate, gypsum, and other mineral matter which have accumulated on the walls or floors of caves at places where water trickles or flows over the rock [10]. Layered deposits of calcium carbonate precipitated on rocks from water trickling over them [20]. (French) coulée stalagmitique; (German) Sinterfall, Sinter; (Greek) asvestolithikon epiphlioma; (Italian) colata stalagmitica, deposito, concrezione, stalagmite; (Russian) nateki; (Spanish) colada estalagmítica; (Turkish) akmataşı; (Yugoslavian) kaskade. See also dripstone.
967	fluid potential	The mechanical energy per unit mass of a fluid at any given point in space and time with regard to an arbitrary state and datum [22].
968	fluorapatite	A cave mineral — Ca₅(PO₄)₃F [11].
969	fluorite	A cave mineral — CaF₂ [11].
970	flume	A channel supported on or above ground [16].
971	fluorescein	A reddish-yellow crystalline compound that imparts a brilliant green fluorescent color to water in very dilute solutions; used to label underground water for identification of an emergence [10]. Also commonly known as uranine. Dye type: Xanthene.
972	fluorescent dyes	Material used in environmental tracing studies that may be detected and measured in small concentrations (≈10–12 mg/L), are inexpensive, relatively nontoxic, and are relatively miscible with the water being traced.
973	fluorometer, filter fluorometer	A highly sensitive instrument used for measuring the fluorescence of water. It is commonly used in water tracing and tracer gaging. Selected filters are used to control the excitation and emission ranges for specific fluorescent dyes of interest. See also scanning spectrofluorophotometer.
974	flushed zone	In geophysical well logging, the zone around the well bore completely invaded by the mud filtrate [16].
975	flute	See scallop.
976	fluviokarst	1. A karst landscape where the dominant landforms are valleys cut by surface rivers. Such original surface flow may relate either to low initial permeability before caves (and hence underground drains) had developed, or to reduced permeability due to ground freezing in a periglacial environment. In both cases the valleys become dry as karst development improves underground drainage [9]. 2. Mixed terranes characterized by both shallow karst and erosional landscape [20]. 3. A predominantly karst landscape in which there is much evidence of past or present fluvial activity [10]. Synonyms: (French) fluviokarst; (German) Fluviokarst; (Greek) fluviokarst; (Italian) fluviocarsimo; (Spanish) fluviokarst; (Turkish) akarsu karstı; (Yugoslavian) fluviokrš, fluviokras, fluviokarst.
977	flux	See specific discharge.
978	foaming agent	See surfactant.
979	foiba	(Italian) 1. A deep wide vertical cavity or the swallow point of a river at the beginning of its underground course. 2. A natural vertical shaft in soluble rock, tending toward cylindrical shape; it may or may not reach the surface. A dome pit [10].
980	fold	A bend in a geologic stratum with two flanks, often in anticlinal and synclinal sequence.
981	food chain	A series of plants and animals linked by their food relationships; the passage of energy and materials from producer through a succession of consumers. Green plants, plant- eating insects, and an insect-eating bat would form a simple food chain [23]. See also food web.
982	food pyramid	The normally diminishing number of individuals and amount of organic material produced at each successive level along a food chain. The declining productivity at each level results from the constant loss of energy in metabolism as the energy passes along the chain [23]. See also trophic level.
983	food web	An interlocking system of food chains. Since few animals rely on a single food source and since no food source is consumed exclusively by a single species of animal, the separate food chains in any natural community interlock and form a web [23].
984	forestry compass	A lightweight, compact instrument to be mounted on a tripod, which functions as a compass and a clinometer, and has a telescopic sight. Some types facilitate measurement of horizontal angles as well as bearings [25].
985	formation	The fundamental unit in rock-stratigraphic classification, consisting of a distinctive mappable body of rock [10]. See also cave formation; speleothem.
986	formation temperature	The prevailing temperature in a given subsurface formation [16].
987	formation stabilizer	A sand or gravel placed in the annulus of the well between the borehole wall and the well screen to provide temporary or long-term support for the borehole [6].
988	form factor	A factor indicating the shape and form of mineral aggregates influencing their hydrodynamic properties [16].
989	fossil	Any remains or traces of animals or plants that lived in the prehistoric past, whether bone, cast, track, imprint, pollen, or any other evidence of their existence [23].
990	fossil cave	A fossil cave is an underground cavity that formed when a carbonate succession was undegoing karstification but subsequently buried. Most fossil caves have been infilled by younger sediments. See neptunian deposits, palaeokarst, and relict cave.
991	fossil karst	See paleokarst.
992	fossile karst	(French) See buried karst.
993	fouling	The process in which undesirable foreign matter accumulates in a bed of filter media or ion exchanger, clogging pores and coating surfaces and thus inhibiting or retarding the proper operation of the bed [6].
994	fountain	A free-flowing well or spring [16]. See also artesian well; spring, artesian.
995	fracture	1. A break or secondary discontinuity in the rock mass, whether or not there has been relative movement across it. Faults, thrusts, and joints are all fractures, but bedding planes, which are primary features, are not. In a more strictly hydrogeological context the term has been used to classify voids in the size range 0.1 to 10mm [9]. 2. Breakage of rock strata [16]. 3. The general term for any mechanical discontinuity in the rock; it is, therefore, the collective term for joints, faults, cracks, etc. See also conduit; fissure.
996	fracture pattern	The spacial arrangement of a group of fracture surfaces.
997	fracture spring	See spring, fracture.
998	fracturing	A formation of breaks in a rock due to folding or faulting [16].
999	francoanellite	A cave mineral — H₆K₃Al₅(PO₄)₈·13H₂O [11].
1000	free pitch	Where a rope or ladder hangs vertically and free of the walls [25].
1001	free-surface stream	In a cave, a stream that does not completely fill its passage [10].
1002	free water	See gravitational water.
1003	free-water elevation	See water table.
1004	freezing point	The point at which a liquid solidifies [16].
1005	fresco	A half-section of a stalactite on the wall of a cave.
1006	fresh water	Water that contains less than 1,000 milligrams per liter (mg/L) of dissolved solids; generally more than 500 mg/L is undesirable for drinking and many industrial uses [22].
1007	freshwater lens	1. Body of fresh ground water found typically beneath permeable limestone islands or peninsular land masses in the tropics. The lens-shaped water body is bounded above by a water table and below by a mixing zone between fresh and saline ground water along the halocline. In the center of the lens freshwater extends below sea-level, and another set of springs exists where dissolutional conduits associated with the lower limit of the lens intersect the rock surface below sea-level [9]. 2. A lenticular form of a freshwater body under oceanic coasts [16].
1008	friction head	Head loss due to energy dissipation by friction [16].
1009	friend	A mechanical camming device used for anchors [25].
1010	Froude number	A dimensionless numerical quantity used as an index to characterize the type of flow in a hydraulic structure that has the force of gravity (as the only force producing motion) in conjunction with the resisting force of inertia. It is the ratio of inertia forces to gravity forces, and is equal to the square of a characteristic velocity (mean, surface, or maximum velocity) of the system divided by the product of a characteristic linear dimension (e.g. diameter or depth) and the gravity constant, acceleration due to gravity, all of which are expressed in consistent units in order that the combinations will be dimensionless. The number is used in open-channel flow studies or where the free surface plays an essential role in influencing motion [1] such as in karst conduits that are not necessarily flowing at pipe-full conditions. See also Chézy equation; Manning equation; Reynolds number.
1011	fullflow spring	See spring, fullflow.
1012	fungling; fungling karst	(Chinese) Isolated limestone hill in alluvial plain, probably similar to mogote [10]. See also fencong; fenglin; mogote; tower karst.
1013	funicular regime	The distribution of continuous liquid phase along pore walls with gaseous phase at the pore center [16].
1014	gage well	A stilling well in which stage measurements are performed [16].
1015	gage station	The point at which stage measurements are performed [16].
1016	gaining stream	A stream or reach of a stream whose flow is being increased by inflow of ground water [22].
1017	galena	A cave mineral — PbS [11].
1018	gallery	A rather large, nearly horizontal passage in a cave [10].
1019	galvanometer	A sensitive current meter [16].
1020	gardening	Clearing stones or other loose material from a route, usually a pitch, which might otherwise be dangerous to a caver continuing [25].
1021	gas-expansion method	The measurement of porosity based on the Boyle-Mariotte’s gas laws [16].
1022	geo	See blowhole.
1023	geode	Hollow globular bodies varying in size from a few centimeters to several decimeters, coated on the interior with crystals [10].
1024	geochemistry	The science of the qualitative and quantitative identification of the elements and their distribution in the earth [16].
1025	geodesy	The science of measuring the geometrical properties of the earth [16].
1026	geohydrologic system	The geohydrologic units within a geologic setting, including any recharge, discharge, interconnections between units, and any natural on man-induced processes or events that could affect ground-water flow within or among those units [22]. See also ground-water system.
1027	geohydrologic unit	An aquifer, a confining unit or a combination of aquifers and confining units comprising a framework for a reasonably distinct geohydrologic system [22].
1028	geohydrology	The branch of hydrology relating to the quantitative treatment of ground-water occurrence and flow [16].
1029	geological column	A vertical cross section through a sequence of formations [16].
1030	geological map	A map on which is recorded geologic information, such as the distribution, nature, and age relationships of rock units (surficial deposits may or may not be mapped separately), and the occurrence of structural features (folds, faults, joints), mineral deposits, and fossil localities. It may indicate geologic structure by means of formational outcrop patterns, by conventional symbols giving the direction and amount of dip at certain points, or by structure- contour lines [1].
1031	geological organ	A cylindrical or funnel-shaped cavity in relatively soluble bedrock which typically has a vertical orientation and is partly or wholly filled with material similar to the overlying sediment cover. They are produced by solution of bedrock and concomitant subsidence of its sedimentary cover. Most have a diameter of 25 cm to 7 m and a depth of 2 to 30 m, but some may be much larger. A depth/diameter ratio of 5 to 20 may be considered representative. In actuality, geological organs are a type of subsidence doline that develops under a cover of younger rock or sediment [17]. Synonyms: (French) Orgue géologigue, poche de dissolution, puits naturel; (Belgian) abannet, cavité de dissolution; (German) geologische Orgel, Orgel, unterirdische Doline, Verwitterungssacke, naturlicher Schacht, Erdorgel, Erdpfeife, Riesentoph, Bodenkarren, (British) sand pipe, sand-gall, gravel-pipe, pipe, pocket deposit, gull; (Italian) organo geologico; (Roumanian) orgile geologice; (Czech) geologické varhany; (Polish) organy geologiczne; (Russian) organ truba, kamin; (Serbo-Croatian.) geološke orgulje; (Slavic) geološke orglje, zapolvje jaški; (Dutch) geologische orgelpijp, aardpijp.
1032	geological section	A vertical section through a sequence of rock masses or strata [16].
1033	geologic control	The influence of geologic factors on hydrogeologic features [16].
1034	geologic correlation	The correlation of geologic formations as shown in geologic logs over a given area [16].
1035	geologic hazard	A naturally occurring or man-made geologic condition or phenomenon that presents a risk or is a potential danger to life and property. Examples include landsliding, flooding, earthquakes, ground subsidence, coastal and beach erosion, faulting, dam leakage and failure, mining disasters, pollution and waste disposal, and seawater intrusion [1].
1036	geologic log	A vertical cross section of the lithologic column indicating geologic and petrographic data [16].
1037	geologic similarity	A model-prototype length ratio [16].
1038	geology	The study of the planet Earth—the materials of which it is made, the processes that act on these materials, the products formed, and the history of the planet and its life forms since its origin. Geology considers the physical forces that act on the Earth, the chemistry of its constituent materials, and the biology of its past inhabitants as revealed by fossils. Clues on the origin of the planet are sought in a study of the Moon and other extraterrestrial bodies. The knowledge thus obtained is placed in the service of man—to aid in discovery of minerals and fuels of value in the Earth’s crust, to identify geologically stable sites for major structures, and to provide foreknowledge of some of the dangers associated with the mobile forces of a dynamic Earth [1].
1039	geomorphic process	The process responsible for the formation and alteration of the earth’s surface [16].
1040	geomorphology	The science of the origin and evolution of land forms [16].
1041	gestation	The gestation phase of speleogenesis follows the inception phase, and the two in combination are essentially equivalent to the more commonly used term “initiation”. The transition from inception to gestation may correspond to the establishment of gravitational laminar flow conditions, and gestation is complete when turbulent flow is achieved [9].
1042	Ghyben-Herzberg conditions	Equilibrium condition at the interface of immiscible freshwater bodies and saltwater bodies in coastal aquifers [16].
1043	gibbs	An ascender with its cam operated by the weight of the caver [25].
1044	glacial deposit	Sedimentary deposits due to transport by glaciers [16].
1045	glacial drift	Sediment material contained, transported, and deposited by glaciers [16].
1046	glacial groove	A groove cut into bedrock by rock fragments at the bottom of a moving glacier [16].
1047	glacial till	An unassorted mixture of glacial drift [16]. Synonym: boulder clay; till.
1048	glaciation	A covering of the land surface by glacier ice [16].
1049	glacier	An extensive body of ice covering the land surface [16].
1050	glacier cave	1. A cave carved out of the ice inside a glacier, not to be confused with an ice cave. Passages are formed by meltwater descending from the glacier surface via crevasses, or by melting on the glacier base. Through caves may connect sinkholes (sometimes called moulins) to glacier snout resurgences, but due to ice movement most glacier caves are ephemeral. The most extensively explored glacier caves were the Paradise Caves on Mount Rainier, USA, whose passages extended for many kilometers, before the glacier wasted away and the caves were destroyed [9]. 2. Cave in ice formed within or at the base of a glacier [10].
1051	glaciofluvial	Pertaining to the meltwater streams flowing from wasting glacier ice and especially to the deposits and landforms produced by such streams [6].
1052	glaciokarst	1. A karst landscape that was glaciated during the cold periods of the Pleistocene and displays major landforms of relict glacial origin. Bare rock scars, locally with glacial striations, and limestone pavements are characteristic, due to the lack of rapid soil formation on the limestones since glacial stripping. Dolines within a glaciokarst are mostly small and immature, as are caves, except where pre-glacial passages are intercepted. Glaciokarst is almost synonymous with alpine karst, and some of the finest is developed on the high plateaus of the Calcareous Alps, south of Salzburg, Austria [9]. 2. A glaciated limestone region possessing both glacial and karst characteristics [10]. (French) karst glaciaire; (German) Gebiet mit karst und Glazial-Formen; (Greek) pagheto-karst; (Spanish) glaciokarst; (Turkish) buzul karstı; (Yugoslavian) glaciokrs̃, glaciokras, glaciokarst. See also alpine karst; nival karst.
1053	glade	1. (Jamaican) An elongate depression, having steep sides, in which a generally flat floor is divided into small basins separated by low divides. 2. (Tennessee) Limestone pavement having extensive growth of cedar trees [10]. See also uvala.
1054	globularite	Small crystals of calcite tipped with spheres composed of radiating fibers [10].
1055	gloop	Synonym for blow hole. Also spelled gloup.
1056	goethite	A cave mineral — FeO(OH) [11].
1057	golyĭ karst	(Russian) See naked karst.
1058	gooseneck	The part of a winding valley resembling in plan the curved neck of a goose. Normally found as part of an entrenched meander [1].
1059	gorge	A narrow passage or canyon in a mountain system [16]. See also canyon.
1060	gour	Flowstone deposit, normally of calcite, built up along the edge of a pool due to precipitation from a thin film of overflow water. Once initiated, by calcite-saturated water overflowing from floor hollows, development is self-enhancing, and the gours can grow into large dams many meters high and wide. Inside the gour pool, more calcite may be precipitated as crystals or pearls. Large flights of gours occur in many caves, with spectacular and well known examples around the Hall of Thirteen in the Gouffre Berger, France. Large travertine, gours can form in the open air, as at Band-i-Amir, Afghanistan [9]. See also rimstone barrage; rimstone barrier; rimstone dam.
1061	graben	A depression formed by a fault block moving downward on the two bounding faults [16].
1062	gradation	The leveling of a surface to a common level [16].
1063	grade	1. Inclination or slope [16]. 2. The class of a cave survey on the basis of the precision of the instruments and the accuracy of the methods [25].
1064	graded	An engineering term pertaining to a soil or an unconsolidated sediment consisting of particles of several or many sizes or having a uniform or equable distribution of particles from coarse to fine [6].
1065	gradient	The change in hydraulic head over some given distance (dh/dL) with ground-water flow usually occurring in the direction of decreasing hydraulic head which requires by convention, the attaching of a minus sign to any equation utilizing a gradient for flow. The maximum value of the directional derivative [16].
1066	grain packing	The spatial arrangement of grains forming porous medium [16].
1067	grain per gallon (gpg)	A common basis for reporting water analyses in the water-treatment industry in the United States and Canada. One grain per U.S. gallon equals 17.12 milligrams per liter [6].
1068	grain shape	The geometrical aspect of grains [16].
1069	granular	Of structure clearly showing grain shape [16].
1070	granule	Small rounded grain or rock fragment [16].
1071	grape formation	See botryoid.
1072	gravel	Waterworn rounded rock grains and fragments [16].
1073	gravimetric moisture content	The ratio of water weight to the weight of solid particles [16].
1074	gravitational head	The component of total hydraulic head related to the position of a given mass of water relative to an arbitrary datum [22].
1075	gravitational water	Water which moves into, through, or out of the soil or rock mass under the influence of gravity [22].
1076	gravity component	The component acting in the direction of gravitation [16].
1077	gravity drainage	The flow of water towards a well under its own weight [16].
1078	gravity spring	See spring, gravity.
1079	grid north	The direction of a north-south grid line on a map. Except for the north-south grid line through the point of origin of the grid, it will differ slightly from true north [25].
1080	grike	(British) 1. A solutionally enlarged vertical or steeply inclined joint in the surface of a karstland, extending for up to a few meters into the limestone [10]. 2. A vertical or sub-vertical cleft in a limestone pavement developed by solution along a joint or system of crisscrossing joints [20]. Grikes separate clints from one another. Synonyms: (British) gryke; (French) lapiaz; (German) Kluftkarren. See also clint; bogaz; limestone pavement.
1081	grotto	1. Hole in small cave or cavern which has eroded in the wall of a main cave. 2. Widely open and shallow cave within a vaulted roof. 3. A cave or chamber preceded by a narrower passage [20]. 4. A small cave, natural or artificial. 5. A room, in a cave system, of moderate dimensions but richly decorated [10]. A grotto is often intricately decorated, and may occur above, at, or below sea-level [20]. Synonyms: (French) grotte, baume, balme; (German) Höhle, Grotte; (Greek) speleon; (Italian) grotta; (Russian) grot; (Spanish) gruta; (Turkish) magarauk; (Yugoslavian) nis ̃a.
1082	ground air	See soil air.
1083	ground slope	The inclination of the land surface with the horizontal [16].
1084	ground water, phreatic water	1. The part of the subsurface water that is in the phreatic zone [10]. Its lower limits are the zone of rock flowage or the lowest fully confining bed; its upper limits are the uppermost fully confining bed or the water table [16]. 2. Used loosely and incorrectly by some to refer to any water beneath the surface. See also phreas; phreatic water; phreatic zone.
1085	ground-water artery	A tubular body of permeable water-filled material surrounded by confining beds [16].
1086	ground-water barrier	Rock or artificial material which has a relatively low permeability and which occurs below the land surface where it impedes the movement of ground water and consequently causes a pronounced difference in the potentiometric surface on opposite sides of it [22].
1087	ground-water basin	1. A general term used to define a ground-water flow system that has defined boundaries and may include permeable materials that are capable of storing or furnishing a significant water supply; the basin includes both the surface area and the permeable materials beneath it [22]. 2. The area throughout which ground water drains towards the same point; it can be larger than the accompanying surface water drainage basin if permeable layers extend outside of the topographic divide [16]. See also drainage basin.
1088	ground-water cascade	The flow of ground water over a subsurface barrier [16].
1089	ground-water cement	A cementing material precipitating at the water table [16].
1090	ground water, confined	Ground water under pressure significantly greater than atmospheric and whose upper limit is the bottom of a confining unit [22]. See also confined; confining unit; confined aquifer.
1091	ground-water dam	A geological stratum serving as a subsurface dam [16].
1092	ground-water discharge	1. Flow of water from the zone of saturation [22]. 2. The water released from the zone of saturation [22].
1093	ground-water divide	1. A ridge in the water table or other potentiometric surface from which ground water moves away in both directions normal to the ridge line [22]. 2. A dividing line between two ground-water basins. 3. In well hydraulics, the streamline with no flow representing the boundary of the aquifer region contributing to well discharge [16]. See also divide. Synonyms: divide; water-table divide.
1094	ground-water flow	The movement of water in the zone of saturation [22].
1095	ground-water flux	The rate of ground-water flow per unit area of porous or fractured media measured perpendicular to the direction of flow [22]. See also specific discharge.
1096	ground-water inventory	The complete quantitative accounting for all volumes of ground water [16].
1097	ground-water mound	A raised area in a water table or other potentiometric surface created by ground-water recharge [22].
1098	ground water, perched	Unconfined ground water separated from an underlying body of ground water by an unsaturated zone. Its water table is a perched water table. Perched ground water is held up by a perching bed whose permeability is so low that water percolating downward through it is not able to bring water in the underlying unsaturated zone above atmospheric pressure [22]. See also perched ground water.
1099	ground-water pumping	1. Directed or oscillatory ground-water movement, along incipient fissures in the rock, that occurs due to very small but significant relative movements of the rocks themselves, maybe as a diurnal, tidal process. It may be one of the driving mechanisms of earliest, inception, phase of speleogenesis [9]. The pumping of a water well to provide water for drinking, irrigation, and manufacturing. but may also be conducted for dewatering purposes.
1100	ground-water recharge	The process of water addition to the saturated zone or the volume of water added by this process [22].
1101	ground-water reservoir	A reservoir in the void space beneath the water table [16].
1102	ground-water system	A ground-water reservoir and its contained water. Also, the collective hydrodynamical and geochemical processes at work in the reservoir [22].
1103	ground-water table	The surface between the zone of saturation and the zone of aeration. Also, the surface of an unconfined aquifer [6]. Synonym: water table.
1104	ground-water travel time	1. The time-required for ground water to travel between two locations [22]. 2. The time required for a unit volume of ground water to travel between two locations. The travel time is the length of the flow path divided by the velocity, where velocity is the average ground-water flux passing through the cross-sectional area of the geologic medium through which flow occurs, perpendicular to the flow direction, divided by the effective porosity along the flow path. If discrete segments of the flow path have different hydrologic properties, the total travel time will be the sum of the travel times for each discrete segment [22].
1105	ground water, unconfined	Water in an aquifer that has a water table. Synonymous with phreatic ground water [22].
1106	grout	A fluid mixture of cement and water (neat cement) of a consistency that can be forced through a pipe and placed where required. Various additives, such as sand, bentonite, and hydrated lime may be included in the mixture to meet certain requirements. Bentonite and water are sometimes used for grout [6].
1107	grout curtain	The filling of void spaces in rocks to prevent the flow of water into and through the rock; most commonly associated with dams.
1108	grouting	The operation by which grout is placed between the casing and the sides of a well bore to a predetermined height above the bottom of the well. This secures the casing in place and excludes water and other fluids from the well bore [6].
1109	grünkarst	See subsoil karst.
1110	gryke	See grike.
1111	guano	An accumulated deposit of animal excrement. In caves it is most commonly associated with bat colonies, but cave dwelling birds such as swifts may also contribute. Guano is only abundant in tropical regions and may be dry and powdery, or a foul, wet, sludge — as in the Niah Caves of Sarawak. It is a vital food source for many troglobites. Consisting mainly of phosphates and nitrate it is valued as a fertilizer or an ingredient of explosives and has commonly been mined. Over 100,000 tons of bat guano have been extracted from Carlsbad Caverns, USA [9]. See also cave guano.
1112	guano cave	A cave containing large amounts of guano [13]. See also cave guano.
1113	guanobia	An animal association feeding on guano. Not considered true cavernicoles as guano is not confined to caves.
1114	gulf	Steep-walled closed depression having a flat alluviated bottom; in some gulfs a stream flows across the bottom [10].
1115	gull	A widened fissure formed by land slipping along valley sides, generally where massive beds such as limestone overlie weaker rocks [9]. See also tectonic cave; windypit.
1116	gully	A deep erosional channel [16].
1117	gushing spring	See spring, vauclusian.
1118	gypsum	1. White or colorless mineral or rock composed of the hydrated calcium sulfate, CaSO₄.2H₂O. Gypsum rock is an evaporite precipitated from sea water and is therefore soluble in water and may contain dissolutional caves. Mineral gypsum is formed in some caves by reactions between the host limestone and sulfates (including sulphuric acid) derived from oxidized sulfide minerals (see pyrite). Gypsum, also referred to as selenite, commonly occurs as transparent crystals, blades, needles or fibres in cave clay deposits. A more spectacular form is as fibrous or curved crystals that may develop into cave flowers on cave walls and ceilings, as for example in parts of the Flint Mammoth Cave System, USA, or grow into large, hanging chandeliers, as in Lechuguilla Cave, New Mexico [9]. 2. A mineral composed of hydrous calcium sulfate [10], CaSO₄·2H₂0.
1119	gypsum cave	Both vadose and phreatic caves can form in gypsum, which is very soluble in water, but they are uncommon because gypsum rock rarely survives total dissolution in the near-surface environments associated with explorable caves. Gypsum caves certainly exist at depth within buried evaporate sequences. In areas of wet climate gypsum caves are generally seen only if encountered by man-made excavations. In contrast, gypsum caves are more common and more extensive in areas that have experienced a long period of dominantly arid climate. The most spectacular gypsum caves are in the Podolie region of the Ukraine, where joint guided maze-cave systems are very extensive — Optimisticeskaja has around 180km of passsage [9].
1120	gypsum flower	See cave flower.
1121	gypsum karst	A karst landscape developed on, or perhaps above, gypsum or similar evaporite rock sequences. Dissolution of gypsum by ground water in buried, interstratal, situations is common and the effects of such dissolution may be expressed at the land surface in the form of subsidence depressions. There are extensive areas of gypsum karst in North America and the Ukraine but British examples are limited to rare caves, exposed by quarrying, and subsidence depressions above dissolved gypsum beds, such as those around Ripon, Yorkshire [9].
1122	habitat	The immediate surroundings (living place) of a plant or animal; everything necessary to life in a particular location except the organism itself [23].
1123	hade	The angle of inclination of a fault (or joint) plane measured relative to the vertical [9]. See also dip.
1124	Halbhöhle	(German) See rock shelter.
1125	Halbkugelkarst	(German) Tropical karst topography containing dome-shaped residual hills surrounding depressions, a kind of Kegelkarst. Also called Kugelkarst [10].
1126	half-exposed karren	These are patches of soil on otherwise bare limestone that attack the rock by means of biogenic CO₂ [3].
1127	half-blind valley	Blind valley in which the stream overflows in floodtime when the swallow hole can not accept all the water [10].
1128	half tube; half-tube	1. An inverted channel with semi-circular cross section seen in cave-passage ceilings, most clearly where the ceiling is an uneroded bedding surface. The half tube originates as part of a phreatic tube guided by the bedding plane, and the lower half is subsequently removed by vadose enlargement. The presence of half tubes provides important evidence of early phreatic-cave development [9]. 2. Trace of a tube remaining in the roof or wall of a cave [10]. See also tube.
1129	Hagen-Poiseuille equation	The equation used to define the laminar flow of water in either fractures or tubes and is given as: Q = -{{w ^{3}b ITAL gamma} OVER {12µ}}{{dh} OVER {dL}} for laminar flow in fractures and: Q = -{{ ITAL pi r ^{4} ITAL gamma } OVER {8µ}}{{dh} OVER {dL}} for laminar flow in tubes which states that the average volumetric discharge of flow through either type of opening is directly proportional to the type, shape, and dimensions of a particular pore and the hydraulic gradient [5]. Note: Q=discharge, w=width of the fissure, b=open portion of the long dimension of the fissure, r=radius of the tube, γ and µ are the specific weight and dynamic viscosity of water respectively, dh/dL=gradient, and a minus sign is attached to the equations to indicate that flow occurs in the direction of deceasing hydraulic head.
1130	halite	The mineral form of sodium chloride (NaCl), or rock salt. Halite occurs, sometimes to considerable thicknesses, in many buried-rock successions, from which it has been extracted both by mining and by redissolving it in water pumped from and back to the surface. The existence of brine springs indicates that natural water movement occurs through buried halite sequences, presumably through voids that could be thought of as caves. Although distinctive halite (or salt) karst features are known in some arid areas, a range of features analogous to those found on karstic rocks such as limestone are unlikely to form, and less likely to be preserved, due to halite’s relative weakness and very high solubility. In Britain expressions of salt karstification are limited to relatively subdued surface features. The “flashes” of the Cheshire area, are hollows, sometimes transformed into water-filled meres, formed by subsidence of overlying rocks and superficial deposits where salt has been dissolved from buried halite beds of Triassic age [9].
1131	hall	In a cave, a lofty chamber which is much longer than it is wide [10]. See also gallery.
1132	halocline	A locally steep salinity gradient along the interface between fresh ground-water and saline ground-water, such as is found at the base of the freshwater lens common beneath many limestone islands in the tropics. Water mixing and microbial activity are important influences on dissolution along the halocline, as shown for instance in blue holes [9].
1133	halomorphic soil	Saline and alkali soils.
1134	hanging blade	A blade projecting down from the ceiling [10]. See also blade.
1135	hannayite	A cave mineral — (NH₄)₂Mg₃H₄(PO₄)₄·8H₂O [11].
1136	hardening	The process of induration [16].
1137	hardness	1. Property of water that prevents lathering because of the presence of cations, mainly calcium and magnesium, which form insoluble soaps [10]. 2. The sum of calcium and magnesium ions expressed as the equivalent amount of calcium carbonate (CaCO₃) [16]. 3. The property to form insoluble salts of fatty acid (soap) [16].
1138	hardpan	This develops when there are secondary calcium carbonate cementations in the lower part of the soil profile [16]. Synonym: mortar bed. See also caliche; havara; nari.
1139	harness	An arrangement of tape for attaching the lower body (seat harness) or the upper (chest harness) to ascenders or descenders [25].
1140	havara	Name given in Cyprus to a soft porous carbonate formation, up to several meters thick, found capping many formations and containing fragments and minerals derived from older rocks; it is probably a type of hardpan or caliche [20]. See also caliche; kafkalla.
1141	haystack hill	(Puerto Rican.) In the tropics, rounded conical hill of limestone developed as a result of solution. Term replaced by mogote [10]. Synonyms: (French) mogote; (German) Mogote; (Italian) mogote, rilievo carsico residuo; (Spanish) mogote; (Turkish) konik kireçtaşı tepesi; (Yugoslavian) hum. See also mogote.
1142	head	The energy contained in a water mass, produced by elevation, pressure, or velocity [6].
1143	head loss	That part of head energy which is lost because of friction as water flows [6].
1144	head, static	The height above a standard datum of the surface of a column of water (or other liquid) that can be supported by the static pressure at a given point. The static head is the sum of the elevation head and the pressure head [22].
1145	head, total	The total head of a liquid at a given point is the sum of three components: (a) the elevation head, which is equal to the elevation of the point above a datum, (b) the pressure head, which is the height of a column of static water that can be supported by the static pressure at the point, and (c) the velocity head, which is the height to which the kinetic energy of the liquid is capable of lifting the liquid [22].
1146	head water	The upper reach of a stream [16].
1147	heat of condensation	The heat released in transforming a substance from its vapor to its liquid state [16].
1148	heat of vaporization	The heat necessary to change water from the liquid to the gaseous state [16].
1149	heel-print karren	See Trittkarren.
1150	helictite	1. Generally small variety of stalactitic calcite growth that is twisted and contorted with no apparent regard for gravity. Helictites form on cave walls, ceilings, and on stalactites. The growth develops as seepage water loses carbon dioxide from near its tip, having been supplied to that point by capillary action through a fine central canal. The helictite shape is created by crystal lattice distortion and crystal form changes within the calcite, but what causes these is uncertain. Impurities may plan a role, and rare groups of parallel growing helictites may be wind-guided [9]. 2. Irregular, twig-like, crystalline growths with varying orientations but often in crystal continuity, formed in caves by precipitation from bicarbonate solutions [20]. 3. A curved or angular twiglike lateral projection of calcium carbonate having a tiny central canal, found in caves [10]. Also known as eccentric anemolite [20]; eccentric stalactite. Synonyms: (French) excentrique; (German) exzentrisch gekrümmter, Tropfstein, Excentriques; (Greek) stalaktits akanonistos; (Italian) stalattiti anomale, eccentiche; (Spanish) estalactita excentrica; (Turkish) düzensiz sarkıt; (Yugoslavian) heliktit. Related to curtain, dripstone, speleothem.
1151	heligmite	An eccentric growing upward from a cave floor or from a shelf in a cave. A curved or angular thin stalagmite [10].
1152	helmet	A miner’s, climber’s or other kind of non-metallic, protective helmet used in caving.
1153	hematite	A cave mineral — Fe₂O₃ [11].
1154	hemimorphite	A cave mineral — Zn₄Si₂O₇(OH)₂·H₂O [11].
1155	herbivore	An animal that eats plants, thus making the energy stored in plants available to carnivores [23]. See also carnivore; insectivore; omnivore.
1156	heterogeneity	A characteristic of a medium in which material properties vary from point to point [22].
1157	heterogeneous	The unequal spacial distribution of aquifer properties [16].
1158	hexahydrite	A cave mineral — MgSO₄·6H₂O [11].
1159	hibbenite	A cave mineral — Zn₇(PO₄)₄(OH)₂·7H₂O [11].
1160	hibernation	A prolonged dormancy or sleeplike state in which animal body processes such as heartbeat and breathing slow down drastically and the animal neither eats nor drinks. Nearly all cold-blooded animals and a few warm-blooded animals hibernate during the winter in cold climates. Extremely large aggregations of bats, crickets, and spiders hibernate in some caves [23].
1161	histo, histoplasmosis	The disease caused by the fungus Histoplasma capsulatum, found in bird and bat guano, especially in the southern USA and the tropics. An occupational disease of cavers, aviary and poultry workers, guano miners, and maintenance workers. Infection is usually caused by breathing the microscopic spores, which infect the lungs, or sometimes the eye. Flu-like symptoms accompanied by low-grade fever, breathing difficulties and pain, and miasma may start about 14 days after exposure and continue for weeks, months, or rarely until death, usually from complications. Treatable with various anti-fungals, such as itroconazole. Often misdiagnosed, as the standard tests may give a false negative [23].
1162	hod	See aisle.
1163	holokarst	1. Karst area with little or no surface runoff or streams; it is underlain by thick carbonate rocks and is characterized by well developed karst surface topography from karren to poljes, extensive subsurface karst features like caves, caverns, galleries, chimneys, etc [20]. 2. Cvijić’s term for a karst area like that of the Dinaric Karst of Slovenia. Such areas have bare surfaces on thick deposits of limestone that extend below sea level, well developed karren, dolines, uvalas, poljes, deep ponors, and extensive cave systems; they have little or no surface drainage [10]. Synonyms: (French) holokarst; (German) Holokarst; (Greek) holokarst; (Italian) olocarsismo, carsismo, maturo; (Spanish) holokarst; (Turkish) tam karst; (Yugoslavian) potpuni krs̃ (kras), holokarst. Contrast causse, merokarst.
1164	homogeneity	A characteristic of a medium in which material properties are identical everywhere [22].
1165	homogeneous	The even spacial distribution of aquifer properties [16].
1166	homogeneous fluid	A fluid that occurs in a single phase [16].
1167	hook gage	A gage for the precise position measurement of liquid levels [16].
1168	hopeite	A cave mineral — Zn₃(PO₄)₂·4H₂O [11].
1169	horizontal angle	The difference in direction of two survey lines measured clockwise in a horizontal plane [25].
1170	horst	A block having been uplifted along its boundary faults [16].
1171	Horton number	Expresses the relative intensity of erosion process in a drainage basin [16].
1172	hot-seat rappel	A method of rappelling in a cave with the rope running under one leg, up across the opposite shoulder and controlled with a hand. The friction of the rope on the body creates a lot of heat, hence its name [13].
1173	hoya, hoyo	(Spanish) A very large closed depression. Used in Puerto Rico for doline, in Cuba for polje [10].
1174	hum	1. Karst inselberg. Residual hill of limestone on a fairly level floor, such as the isolated hills of limestone in poljes. In some tropical areas, used loosely as synonym for mogote [10]. 2. Yugoslavian term for an isolated residual hill on the bottom of a polje [20]. Synonyms: (French) butte témoin; (German) (Karstinselberg), Hum; (Greek) karstiki martyree lophi; (Italian) testimoni carsici; (Russian) karstovij ostanec; (Spanish) hum; (Turkish) karst adatepesi; (Yugoslavian) hum. See also karst inselberg; mogote.
1175	humidity, absolute	The moisture content by weight per unit volume of air [16].
1176	humidity, relative	The ratio, expressed as a percentage, of the amount of water vapor actually present in air of a given temperature, as compared with the greatest possible amount of water vapor that could be present in air at that temperature. Calculation of relative humidity can be done from tables, special slide rules or calculators, graphs, or complex equations [23]. See also hygrometer; psychrometer.
1177	humus-water grooves	This is a special type of meandering karren or wall karren in which the water originated in humus covering. Water originating from a humus cover has an excess of CO₂ and is therefore, very aggressive and can dissolve large amounts of limestone. Thus humus- water grooves can be very deep but after approximately 2–3 meters, the grooves flatten out and continue as normal meanders or wall karren [3]. See also meander karren; wall karren.
1178	huntite	A cave mineral — CaMg₃(CO₃)₄ [11].
1179	hydration	The act by which a substance takes up water by absorption and/or adsorption [6].
1180	hydraulic barrier	A general term referring to modifications of a ground-water flow system to restrict or impede movement of contaminants [22].
1181	hydraulic conductivity	1. A proportionality constant relating hydraulic gradient to specific discharge which for an isotropic medium and homogeneous fluid, equals the volume of water at the existing kinematic viscosity that will move in unit time under a unit hydraulic gradient through a unit area measured at right angles to the direction of flow [22]. 2. The volume of water that will move through a medium in a unit of time under a unit hydraulic gradient through a unit area measured perpendicular to the direction of flow [22]. 3. The ability of a rock unit to conduct water under specified conditions [10]. It is typically expressed as gpd/ft2, ft/day, or m/day.
1182	hydraulic conductivity, effective	The rate of flow of water through a porous medium that contains more than one fluid, such as water and air in the unsaturated zone, and which should be specified in terms of both the fluid type and content and the existing pressure.
1183	hydraulic diffusivity	See diffusivity, hydraulic.
1184	hydraulic discharge	The discharge of ground water through springs or wells [16].
1185	hydraulic fracturing	The formation of artificial fractures in rock systems around a well by high pressure fluid injections [16].
1186	hydraulic gradient	1. The change in static head per unit of distance in a given direction. If not specified, the direction generally is understood to be that of the maximum rate of decrease in head [22]. 2. Slope of the water table or potentiometric surface [22]. 3. A chance in the static pressure of ground water expressed in terms of the height of water above a datum, per unit of distance in a given direction [22].
1187	hydraulic head	The height above a datum plane (such as sea level) of the column of water that can be supported by the hydraulic pressure at a given-point in a ground-water system. For a well, the hydraulic head is equal. to the distance between the water level in the well and the datum plane [22].
1188	hydraulic jump	1. A standing surge of water passing from below critical depth in open channel flow [16]; often occurs in caves. 2. An abrupt depth variation in rapidly varying channel flow [16].
1189	hydraulic profile	A vertical section of the potentiometric surface [16].
1190	hydraulic radius	The ratio of the filled cross-sectional area to wetted perimeter [16].
1191	hydrochemical facies	Distinct zones that have cation and anion concentrations of diagnostic chemical character of water solutions in hydrologic systems which is describable within defined composition categories [22].
1192	hydrocompaction	The process of volume decrease and density increase that occurs when moisture-deficient deposits compact as they are wetted for the first time since burial [21]. Synonym: shallow subsidence.
1193	hydrogeologic	Those factors that deal with subsurface waters and related geologic aspects of surface waters.
1194	hydrograph, characteristic	A hydrograph based on the unit step process.
1195	hydrodynamic dispersion	1. The spreading (at the macroscopic level) of the solute front during transport resulting from both mechanical dispersion and molecular diffusion [22]. 2. The dynamic dispersion of fluid particles in flow through a porous medium due to velocity changes in the pore channels [16].
1196	hydrodynamic dispersion, coefficient of	See dispersion coefficient.
1197	hydrogeochemistry	The geochemistry of water as related to the occurrence of subsurface water [16].
1198	hydrogeologic	Those factors that deal with subsurface waters and related geologic aspects of surface waters [6].
1199	hydrogeologic unit	1. Any soil or rock unit or zone which by virtue of its hydraulic properties has a distinct influence on the storage or movement of ground water [22]. 2. Means a soil or rock unit or zone which by virtue of its porosity or permeability, or lack thereof, has a distinct influence on the storage or movement of ground water [22].
1200	hydrogeology	The study of subsurface waters in their geological context [16].
1201	hydrograph	1. A graph relating stage, flow, velocity, or other characteristics of water with respect to time [22]. 2. A time record of stream discharge at a given cross section of the stream or of the stream surface elevation at a given point [16].
1202	hydrograph separation	The separation of a hydrograph into its different components to analyze flow contributions [16].
1203	hydrography	The geographical description of water bodies on the earth’s surface [16].
1204	hydrologic barrier	See barrier, hydrologic.
1205	hydrologic budget	The quantitative accounting of all water volumes and their changes over time for a given basin or province [16].
1206	hydrologic properties	Those properties of a rock that govern the entrance of water and the capacity to hold transmit, and deliver water, such as porosity, effective porosity, specific retention, permeability, and the directions of maximum and minimum permeabilities [22].
1207	hydrology	The study of atmospheric, surface, and subsurface waters and their connection with the water cycle [16].
1208	hydromagnesite	A cave mineral — Mg₅(CO₃)₄(OH)₂·4H₂O [11].
1209	hydrometeorology	Meteorology dealing with water in the atmosphere [16].
1210	hydrometric station	A station at which there usually are a number of hydrometric measurements being performed [16].
1211	hydrometry	The science of water measurements [16].
1212	hydrophilic	Having a great affinity for water [16].
1213	hydrophobic	The repelling of water [16].
1214	hydrophyte	A plant requiring large amounts of moisture for growth [16].
1215	hydrosphere	That part of the earth that contains liquid or solid water [16].
1216	hydrostatic pressure	The pressure due to a column of water [25].
1217	hydrostratigraphic unit	See hydrogeologic unit.
1218	hydroxylapatite	A cave mineral — Ca₅(PO₄)₃(OH) [11].
1219	hydrozincite	A cave mineral — Zn(CO₃)₂(OH)₆ [11].
1220	hyetograph	A graph of rainfall intensity against time [16].
1221	hygrometer	1. An instrument that reads the humidity in the air directly; some are based on a hair’s ability to shrink or expand with humidity, or on certain electronic chips. Generally, a psychrometer is more accurate at higher humidities (above 95%) [23]. 2. Apparatus for the direct measurement of the relative humidity in the atmosphere [16]. See also psychrometer.
1222	hygroscopic nucleus	Small solid particles around which water condensates (cloud formation) [16].
1223	hydroscopic water	Condensed water at a solid surface [16].
1224	hypogeum	The subterranean environment [23].
1225	hypolimnion	A deep layer in stratified water [16].
1226	hydroscopic coefficient	The amount of absorbed water on the surface of soil particles in an atmosphere of 50% relative humidity at 25°C [16].
1227	hypogean	Pertaining to, or living in, regions deeper than the endogean zone. See also epigean.
1228	ice	Crystallized water formed below the freezing point (H₂O) [16].
1229	ice cave	1. Any cave in rock that is partly filled with ice. The term should not be applied to glacier caves. The ice may form in massive icicles and flows, when percolation water from unfrozen rock seeps into a cave containing freezing air drawn in from outside. This is a seasonal situation in many alpine caves, and if winter freezing exceeds summer melting the ice may become permanent, as in Austria’s Dachstein and Eisriesenwelt caves. Alternately water vapor may crystallize out as hoar frost, commonly forming large hexagonal ice crystals that line the walls of a freezing cave, as in Grotte Valerie, northern Canada [9]. 2. A cave, generally in lava or limestone, in which the average temperature is below 0°C., and which ordinarily contains perennial ice. Ice may have the form of stalactites, stalagmites, or flowstone [10]. (French) glacière; (German) “Eishöhle”; (Greek) paghoménon spíleon; (Italian) ghiacciata naturale, grotta ghiacciata; (Russian) ledjanaja pescera; (Spanish) cueva helada, cueva de hielo; (Turkish) buz magarası; (Yugoslavian) ledena pećina, ledenjac̃a, ledena jama. See glacier cave.
1230	illite	A clay mineral.
1231	imbibition	1. The absorption of a fluid, usually water, by a granular rock or other porous material, under the force of capillary attraction, and in the presence of pressure. 2. Fluid displacement in porous media as a result of capillary forces only [16]. 3. Absorption of water by plants. Synonym: capillary percolation.
1232	immiscible	1. Two or more liquids that are not readily soluble [22]. 2. The chemical property of two or more phases that, at mutual equilibrium, cannot dissolve completely in one another, e.g., oil and water [22]. 3. The quality of liquids exhibiting a clear interface where they are in contact; not miscible [16].
1233	impermeable	A characteristic of some geologic material that limits their ability to transmit significant quantities of water under the pressure differences ordinarily found in the subsurface [22].
1234	impervious	Not permitting the flow of water [16].
1235	impervious lens	An impermeable, lens-shaped body of sediment in an otherwise permeable aquifer [16].
1236	imported water	Water coming from outside the ground-water basin under consideration [16].
1237	impound	The collecting of water by damming [16].
1238	inception	The earliest stage of speleogenesis. The start of the inception phase marks the transition from “rock with no caves” (in the widest sense) to “rock with caves”, and extends through whatever time interval is required for gravitational laminar flow conditions to be established in a given situation (see gestation and initiation) [9].
1239	inception horizon	A part of a rock succession that is particularly susceptible to the effects of the earliest cave forming processes and hence is critical to the origin of most non-tectonic caves. By virtue of physical, lithological or chemical deviation from the predominant carbonate facies within the sequence, it passively or actively favors the localized inception of dissolutional activity [9]. See also inception.
1240	incision	See entrenchment.
1241	initiation	The early parts of speleogenesis, generally up to the point of breakthrough from laminar to turbulent flow, at an average conduit diameter of 10mm. Initiation includes, but is not the same as, inception [9].
1242	inclinometer	An instrument to measure the inclination of surfaces [16].
1243	incoherent material	Unconsolidated material [16].
1244	incrustation	1. Deposition of a crust (of calcite, etc.) upon an object by precipitation from water oversaturated with salts (calcium bicarbonate, etc.) [20]. 2. The deposition of mineral matter by water [16]. Synonyms: (French) incrustation; (German) Krustenbildung; (Greek) epiphlioma; (Italian) incrostazione; (Russian) obrazovanie natecnih kor; (Spanish) incrustción; (Turkish) kabuk baglama, kabuklaşma; (Yugoslavian) inkrustacija.
1245	induced activity	The activity or response of a system that has been subjected to an artificial excitation [16].
1246	induced infiltration	An increase in infiltration from a surface water body by the lowering of the original water table [16].
1247	induced recharge	A method of withdrawing ground water at strategic points to induce natural recharge [16].
1248	indurated rock	A rock that has been hardened and solidified by diagenetic processes [16].
1249	infiltrability	The ease of infiltration [16].
1250	infiltration	The downward entry of water into the soil or rock [22].
1251	infiltration basin	A basin in which water is spread for recharge.
1252	infiltration capacity	The maximum rate at which a soil or rock is capable of absorbing water or limiting infiltration [22].
1253	infiltration gallery	A horizontal conduit for the purpose of intercepting ground water [16].
1254	infiltration index	The average rate of infiltration throughout a given rain storm [16].
1255	infiltration rate	1. The rate at which a soil or rock under specified conditions absorbs falling rain, melting snow, or surface water expressed in depth of water per unit time [22]. 2. A characteristic describing the maximum rate at which water can enter the soil or rock, under specified conditions, including the presence of an excess of water. It has the dimensions of velocity [22].
1256	infiltrometer	Apparatus for measuring the amount of infiltration [16].
1257	inflow cave, influent cave	Cave into which a stream flows or formerly entered [10].
1258	influent stream	See losing stream.
1259	infrared light	Light not visible to the human eye, with wavelengths longer than those of visible red light and shorter than those of radio waves [23].
1260	initial abstraction	The maximum amount of rainfall absorbed without producing runoff [16].
1261	inject, to	1. The introduction of pressurized fluids into a porous subsurface formation [16]. 2. The introduction of tracer materials (e.g. fluorescent dyes) into the subsurface.
1262	injection head	A swivel head connector through which drilling fluid is injected into the drill pipe [16].
1263	injection well	Well used for emplacing fluids into the subsurface [22].
1264	injection zone	A geological “formation”, group of formations, or part of a formation receiving fluids through a well.
1265	injectivity	The capacity of a well or formation to accommodate pumped in liquid [16].
1266	inlet cave	A cave developed beneath a swallow hole where a surface watercourse first passes underground in karst limestone [19].
1267	input point	Points where water enters an underground drainage route or aquifer. An obvious type of input point is a surface sink or swallow hole, where allogenic drainage has direct access to a conduit system within a carbonate aquifer. Less obvious are points where drainage enters a potential carbonate conduit-system from adjacent non-carbonate strata (such as a porous sandstone aquifer) or where water utilizes a fracture system to pass through otherwise relatively impermeable beds and into the carbonate aquifer [9].
1268	insectivore	An animal that feeds on insects. Almost all species of North American bats are insectivores [23]. See also carnivore; herbivore; omnivore.
1269	in-situ density	The density of water measured at its actual depth [22]. See also potential density.
1270	insulated stream	A stream neither receiving nor abstracting water from a ground-water body because of an impermeable bed [16].
1271	insurgence	A term proposed to describe a point of inflow for surface water into subsurface conduits. It has not gained wide usage and is not recommended for use. Diffuse insurgence may be used to describe the slow percolation of water through overburden and tight pores in the rock. Confluent insurgence may be applied to water entering the rock via identifiable streams sinking into the subsurface while a confluent insurgence complex would apply to a cluster of insurgences. Abandoned insurgences is the term applied to inflow points no longer used by infiltrating water. An overflow insurgence is the term used to describe insurgences utilized only during periods of high flow [12].
1272	intake area, recharge area	The surface area in which water is absorbed into an aquifer eventually to reach the zone of saturation [10].
1273	interaquifer flow	The flow that occurs between aquifers through fracture openings or through the wellbore [16].
1274	interbedded	Pertaining to beds or sedimentary material intercalated in a parallel fashion into a main stratum [16].
1275	interbedding	A bed between layers of different material [16].
1276	interception	The abstraction of direct rainfall on vegetation cover [16].
1277	interception loss	That part of rainfall retained by the aerial portion of vegetative cover [16].
1278	interdigitation	The lateral interlocking of sedimentary series [16].
1279	interface	1. The contact zone between two materials of different chemical or physical composition [22]. 2. The contact plane of two immiscible liquids [16].
1280	interference	The condition occurring when the area of influence of a water well comes into contact with or overlaps that of a neighboring well, as when two wells are pumping from the same aquifer or are located near each other [6].
1281	interflow	Subsurface runoff [16].
1282	intergranular stress	The stress between grains in a solid matrix [16].
1283	intergranular voids	Generally primary or secondarily enhanced voids within rocks, with average dimensions of 0.00l to 0.lmm. Such voids, or pores, may provide interconnected porosity in many karst rocks and allow early water movement under laminar flow conditions [9].
1284	intermittent spring	See spring, intermittent.
1285	intermittent stream, intermittent river	1. A stream or river which flows only in direct response to precipitation or to intermittent discharge of a spring; not confined to karst areas, but not uncommon in them [20]. 2. A stream or river that flows at irregular intervals [16]. Synonyms: (French) cours d’eau intermittent; (German) intermittierender Fluß, episodischer periodischer Fluß; (Greek) dialípon potamós; (Italian) torrente intermittente; (Spanish) corriente intermitente; (Turkish) kesintili akarsu; (Yugoslavian) sus ̃ica, suvaja. Contrast with interrupted river.
1286	intermontane basin	A basin lying between two mountain ranges [16].
1287	internal drainage	Drainage in a closed basin and not reaching the sea [16]. It is common in maturely karsted terranes where surface water bodies are relatively nonexistent.
1288	interstice	1. An opening in a rock or soil that is not occupied by solid matter [22]. 2. An opening or space which may be occupied by air, water, or other gaseous or liquid material [22]. Synonymous with void, pore. See also pore; pore space; porosity; porosity, effective; porosity, primary; porosity, secondary.
1289	interstitial ice	Ice occurring below the surface in soil pores [16].
1290	interstitial medium	Spaces between grains of sand or fine gravel filled with water which contains phreatobia [25].
1291	interstitial water	Water held in small wedge like interstices at grain contact [16].
1292	interstratal karst; interstratal karstification	1. Features formed by the dissolutional removal of all or part of a buried rock unit. Interstratal-karst features are common within highly soluble evaporite rocks such as gypsum and halite, and may be equally common, but less readily recognized, within the preserved remnants of carbonate successions. Interstratal karst should not be confused with buried karst. The finest interstratal karst in Britain is the extensive cave development in the limestones beneath the Namurian Millstone Grit plateaux of South Wales, where the large collapse dolines in the Millstone Grit are interstratal-karst landforms [9]. 2. The process of karstification of highly soluble rocks (e.g., gypsum, anhydrate, and salt) that are overlain by less soluble rocks (e.g., shales), but are still selectively dissolved by circulating ground water [10].
1293	interstratal karst	Karst topography that is covered by and developed beneath pre-karst rock or sediment and may or may not be part of the contemporary landscape. It is younger than its cover and is formed by the solution of soluble rock in the subsurface, most commonly beneath relatively insoluble rock such as sandstone or chert. The term refers to areal solution rather than to cave development but is also applicable to rejuvenated mantled karst and rejuvenated buried karst. Subsoil karst is transitional to interstratal karst [17]. Synonyms: (French) karst sous-jacent; (German) unterirdisches Karstphänomen; (Greek) kalyménon karst; (Italian) carso coperto; (Spanish) karst interstradal; (Turkish) tabakalar arası karst. See also buried karst; denuded karst; covered karst.
1294	inter-permafrost karst	See permafrost karst; sub-permafrost karst.
1295	interrupted river, interrupted stream	1. A river which flows for part of its course on the surface, and part underground in caves [20]. 2. A stream interrupted over space [16]. 3. A discontinuous stream [16]. Synonyms: (French) rivière interrompue; (German) periodischer Fluß ?, Karstfluß, versickernder Fluß; (Greek) thiakekoménos potamós; (Russian) peresihauchaj reka, syhaja reka; (Spanish) rio sumente; (Turkish) yer yer akan nehir; (Yugoslavian) sus ̃ica, suvaja, periodićka rijeka (reka). See also lost river; intermittent stream.
1296	intrinsic permeability	See permeability, intrinsic.
1297	inundation	The covering of an area by flood waters [16].
1298	invaded zone	In geophysical well logging, the zone in which an appreciable amount of mud filtrate has penetrated [16].
1299	invasion	In geophysical well logging, the penetration of a fluid into the porous medium [16].
1300	invasion depth	The depth to which drilling mud filtrate penetrates into a formation [16].
1301	invertebrate	An animal, such as a planarian, snail, or crayfish, without a backbone [23]. See also vertebrate.
1302	inverted siphon	See water trap.
1303	ion	An element or compound that has gained or lost an electron so that it is no longer neutral electrically and now carries a charge [6].
1304	ion mobility	The ease with which ions move in an electrolytical solution [16].
1305	irreducible saturation	The lowest water saturation obtainable by mechanical reduction methods [16].
1306	irrigation	The artificial watering of fields for crop production [16].
1307	irrigation requirement	The water needed for crop production exclusive of precipitation [16].
1308	irrigation return flow	The part of artificially applied water that is not consumed by evapotranspiration and that migrates to an aquifer or surface water body [22].
1309	irrotation flow	Potential flow or flow with no rotational component [16].
1310	isobath	A line of equal depth [16].
1311	isochrone	A line connecting water levels in observation wells for a given instant in time [16].
1312	isohyet	A line of equal rainfall [16].
1313	isopiestic line	A contour on a piezometric surface connecting points of equal static level [16].
1314	isopleth	A line of equal distance from the point of outflow of a basin [16].
1315	isopotal line	A line of equal infiltration capacity [16].
1316	isotherm	A line of equal temperatures [16].
1317	isotope tracer	Tracer which is an isotope of an element present in the water; it may be artificial (added to water) or natural (present in the water) [20]. Synonyms: (French) traceur isotopique; (German) Markierung durch radioaktive Isotopen; (Greek) isotopicos ichnithetis; (Italian) tracciante isotopico; (Russian) izotopnij indikator; (Spanish) trazador isotópico; (Turkish) izotop izleyicisi; (Yugoslavian) izotopni traser.
1318	isotropic	Equal properties in all directions.
1319	isotropic mass	A mass having the same property or properties in all directions [22].
1320	isotropy	The condition in which the property or properties of interest are the same in all directions [22].
1321	izdan	A general Yugoslavian term for a ground-water reservoir from which ground water may readily be extracted; it is not specifically a karst term [20].
1322	jama	1. (Slavic) Vertical or steeply inclined shaft in limestone, known as abîme or aven in France and as pothole in England. 2. Any cave [10]. Synonyms: (French) jama; (German) Abgrund, Schacht, Schlund; (Greek) karstikon phrear; (Italian) abisso, foiba, pozzo, voragine; (Russian) karstovij kolodec, karstovaja sahta; (Spanish) sima, pozo, avenc; (Turkish) obruk; (Yugoslavian) bezdan, japaga, zvekara, pekel, brezno, prepad, propast. Related to cenote, doline, obruk, pit, shaft, shake hole.
1323	jarosite	A cave mineral — KFe₃(SO₄)₂(OH)₆ [11].
1324	joint	1. A break of geological origin in the continuity of a body of rock occurring either singly, or more frequently in a set or system, but not attended by a visible movement parallel to the surface of the discontinuity. 2. A junction or connection of mechanical elements such as drill pipe [16]. See also fracture.
1325	joint diagram	A diagram constructed by accurately plotting the strike and dip of joints to illustrate the geometrical relationship of the joints within a specified area of geologic investigation.
1326	joint or fault set	A group of more or less parallel joints or faults.
1327	joint or fault system	A system consisting of two or more joint or fault sets or any group of joints or faults with a characteristic pattern (e.g., radiating, concentric, etc.).
1328	joint pattern	A group of joints which form a characteristic geometrical relationship, and which can vary considerably from one location to another within the same geologic formation.
1329	joint-plane cave	A cavity high in relation to width developed along steeply dipping joint planes [10].
1330	jumar	An ascender with a simple finger-operated safety catch, a handle and several attachment points [25].
1331	juvenile water	Water that has not been part of the hydrosphere before and is derived from the earth’s interior [16].
1332	kafkalla	A term used in Cyprus for the hardened upper portion of crust of havara [20]. See also caliche; havara.
1333	kame	A stratified glacial sand and gravel deposit forming a small, conical hill [16].
1334	Kamenica, Kamenitza	(German, possibly of Slavic origin; plural, Kamenice.) A small depression (a few meters in diameter and several centimeters deep) in a level calcareous surface, enlarged by the solution effect of water collecting between slight undulations. It is developed vertically at first by stagnant water; the steep sides thus evolved then induce the flow of water which flutes the slope and so eventually widens the basin. Sediments and low orders of plant life frequently collect on the even floor, the latter aiding further solution by reactivating the pH of the water [19]. Synonyms: (French) kamenice; (German) Opferkeßel; (Greek) lakouva, ythrolakkos; (Russian) bljudoe; (Spanish) cuenco, tinajita; (Turkish) erime tavası; (Yugoslavian) kamenica, skalne kotlice, scalba, skalnica. See also solution pan; water pot.
1335	kankar; kunkar	(Australian) See caliche.
1336	Kannelierungen	(German) See Rillenkarren.
1337	kaolin	A common clay mineral [16].
1338	karabiner	See carabiner.
1339	Karren	(German) Channels or furrows, caused by solution on massive bare limestone surfaces; they vary in depth from a few millimeters to more than a meter and are separated by ridges. In modern usage, the terms are general, describing the total complex of superficial solution forms found on compact pure limestone. Classified into several kinds, the most common of which are: Rillenkarren — shallow channels separated by sharp ridges 2-3 centimeters apart; Rinnenkarren — flat-bottomed grooves several centimeters apart; Kluftkarren — joints enlarged by solution; Spitzkarren — large deep grooves extending down from steep spires or pinnacles; meandering karren (Mäanderkarren) — small winding or meandering channels; round karren (Rundkarren) — karren having rounded channels and intervening rounded ridges, probably reexhumed after formation under soil or peat; Flachkarren — equivalent to the English clint; Bodenkarren — karren formed beneath the soil [10]. Synonyms: (French) lapiés; (German) Karren, Schratten; (Greek) thaktyloglyphae, amaxotrochiae; (Italian) campo solcato; (Russian) karri; (Spanish) lapiaz; (Turkish) erime olugu; (Yugoslavian) škrape, škripovi, grižine, žlebici, s ̃kraplje.
1340	Karren, free	(German) Bare karst; water flows unhindered over the limestone surface [3].
1341	Karrenfeld; Karren field	(German) An area of limestone dominated by karren [10]. These appear as bare karst and consist of the sum of exposed and half-exposed karren, occasionally also of covered karren which have become exposed. They range in size from a few hectares to a few hundred square kilometers [3]. Synonym: (Turkish) erime olugu alanı. See also clint; grike.
1342	karst	(Internationally used term, originally the German form of the Slavic word kras or krš, meaning a bleak waterless place; it is the German name for a district east of Trieste having such terrane.) A terrane, generally underlain by limestone or dolomite, in which the topography is chiefly formed by the dissolving of rock, and which may be characterized by sinkholes, sinking streams, closed depressions, subterranean drainage, and caves [10]. The term karst unites specific morphological and hydrological features in soluble (mostly carbonate) rocks. Morphological features include karren, dolinas (sinkholes), jamas, ponors, uvalas, poljes, caves, caverns, etc. Hydrological features include basins of closed drainage, lost rivers, estavelles, vauclusian springs, submarine springs, more or less individualized underground streams and incongruity of surface and underground divides. Karst is understood to be the result of natural processes in and on the earth’s crust cause by solution and leaching of limestones, dolomites, gypsum, halite, and other soluble rocks [20]. Synonyms: (French) karst; (German) Karst; (Greek) karst; (Italian) carso, carsismo; (Russian) karst; (Spanish) karst; (Turkish) karst; (Yugoslavian) krš, kras. See also buried karst; cone karst; covered karst; exhumed karst; Halbkugelkarst; Holokarst; Kegelkarst; Merokarst; microkarst; naked karst; paleokarst; pseudokarst; relict karst; Spitzkegelkarst; subjacent karst; syngenetic karst; thermokarst; tower karst.
1343	karst aquifer	See aquifer, karst.
1344	karst barré	(French) 1. A karst terrane of limited area completely surrounded by rocks of low permeability [10]. 2. Term for karst areas whose lower part is enclosed and bordered by more or less impervious rocks which impedes ground-water flow out of the karst area. Synonyms: (French) karst barré; (German) Riegelkarst; (Greek) phragmenon karst; (Spanish) karst cerrado; (Turkish) setli karst; (Yugoslavian) zagaceni krs̃ (kras), zajezeni kras.
1345	karst base level	Level below which karstification does not or has not taken place [10]. Synonyms: base level of karstification [20]; (French) niveau de base karstique; (German) Korrosionsniveau; (Greek) basis apokarstoseos, or better “patoma apokarstoseos”; (Italian) livello di base della attività carsica; (Spanish) nivel de base kárstico; (Turkish) karstlaşma tabani; (Russian) bazis karsta; (Yugoslavian) baza krškog procesa, baza karstifikacije, baza zakrasevanja.
1346	karst breccia	See collapse breccia; solution breccia.
1347	karst bridge	A natural bridge or arch in limestone [10].
1348	karst couvert	(French) See covered karst.
1349	karst fens	1. Marshes developed in sinkhole terrain; swampy solution fens [10]. 2. Marsh or swamp formed by plants overgrowing a karst lake or seepage. Synonyms: (French) marais karstique; (German) Karstsumpf ?; (Greek) karstikon elos; (Italian) palude o acquitrinio carsico; (Russian) karstovoje boloto; (Spanish) laguna karstica; (Turkish) karst bataklıgı; (Yugoslavian) lokva, kal.
1350	karst fenster	See karst window.
1351	karst fossile	(French) See buried karst.
1352	karst hydrology	1. The branch of hydrology dealing with hydrological phenomena on and in regions and areas composed totally or in part of rocks which are soluble in water, such as limestones, dolomites, gypsum, and halite [20]. 2. The drainage phenomena of karstified limestones, dolomites, and other slowly soluble rocks [10]. Synonyms: (French) hydrologie karstique; (German) Hydrologie des Karsts; (Greek) karstike hydrologia; (Italian) idrologia carsica; (Russian) gidrologija karsta; (Spanish) hidrología kárstica; (Turkish) karst hidrolojisi; (Yugoslavian).
1353	karst inselberg	A residual hill of soluble rock in a polje [20]. Synonyms: (French) inselberg karstique; (German) Karstinselberg (Hum, Mogote); (Greek) karstiki martyres lophi; (Italian) rilievo carsico residuo; (Russian) karstovij ostanec; (Spanish) relieve kástico residual; (Turkish) karst tepesi; (Yugoslavian) hum.
1354	karst lake	1. Lakes on karst surface, frequently connected with ground water; lakes in subterranean hollows (caves and caverns) [20]. 2. A large area of standing water in extensive closed depression in limestone [10]. Synonyms: (French) lac de karst; (German) Karstsee; (Greek) karstiki limni; (Italian) lago carsico; (Russian) karstovoe ozero; (Spanish) lago kãrstico; (Turkish) karstik gölü; (Yugoslavian) krško (krasko) jezero.
1355	karst margin plain	A plain generally on limestone between higher country of limestone on one side and of less pervious rocks on the other, but having a cover of impervious detritus, which allows surface drainage [10].
1356	karst noyé	(French) See drowned karst.
1357	karst nu	(French) See exposed karst.
1358	karst plain	1. Large flat surface in karst formed by erosion and corrosion [20]. 2. A plain on which closed depressions, subterranean drainage, and other karst features may be developed. Also called karst plateau [10]. Synonyms: (French) plateau karstique; (German) Karstebene, Karstrandebene, Korrosionsfläche; (Greek) karstikon pedhion; (Italian) piano carsico; (Russian) karstovaja ravnina; (Spanish) llanura kárstica; (Turkish) karst ovası; (Yugoslavian) krs ̃ka zaravan, površ, kras ̃ki ravnik. See also marginal polje.
1359	karst polje	See polje.
1360	karst pond	Closed depression in a karst area containing standing water [10].
1361	karst river	1. A river (or stream) flowing in a karstic area, either on the surface of the ground or through an underground cave system [20]. 2. A river that originates from a karst spring [10]. Synonyms: (French) rivière karstique; (German) Karstfluß; (Greek) karstikós potamós; (Italian) corso d’acqua carsico; (Russian) karstovaja reka; (Spanish) río kárstico; (Turkish) karst nehiri; (Yugoslavian) krs̃ka rijeka, kraska reka.
1362	karst seep	Place where karst ground water oozes out at the surface of the ground; sometimes overgrown and then forming a karst fen [20]. Synonyms: (French) suitement karstique; (German) Karstgrundwaßer-Austritt; (Greek) karstiki thiaroi; (Russian) visacivanie karstovih vod; (Spanish) zona de absorción; (Turkish) karst sızıntısı; (Yugoslavian) močilo.
1363	karst shaft	A vertical or steeply-sided natural opening a few tens to a few hundred meters deep, formed by solution or erosion of vertical or sub-vertical fractures or fissures by down flowing surface water. Such a pit, formed from above, may connect with a chimney formed from below. Synonyms: (French) karst shaft; (German) Schacht, Schaft; (Greek) karstikós lákkos; (Italian) voragine, inghiottitoio; (Russian) karstovaja sahta; (Spanish) sima; (Turkish) karst bacası; (Yugoslavian) jama. Related to dolina, jama, obruk, pit.
1364	karst sous-jacent	(French) See interstratal karst.
1365	karst spring	See spring, karst.
1366	karst topography	Topography dominated by features of solutional origin [10]. Geomorphically, the dominant features usually but not always obviously present, are sinkholes and caves. In tropical regions, karst towers (e.g. mogotes) may also dominate the landscape.
1367	karst valley	1. Valleys in karst are normally distinctive due to the lack of integrated surface drainage. Most are either blind (due to being closed where the drainage sinks underground), headless or pocket (where a river emerges from a spring) or dry (where surface flow has been lost due to underground capture). The exception is the allogenic valley, where a river completely traverses a karst, normally because underground conduits at or below valley floor level are immature. Fine examples of allogenic karst valleys are Dove Dale in the Peak District and France’s Tarn Gorge [9]. 2. Elongated solution valley in limestone [20]. 3. Valley produced by collapse of a cavern roof [10]. Synonyms: (French) vallée karstique; (German) Karsttal, Karstgaße; (Greek) Karstikı kilás; (Italian) valle carsica; (Russian) karstovaja dolina; (Spanish) valle kárstico; (Turkish) karst vadisi; (Yugoslavian) krška (kraska) dolina.
1368	karst vert	See subsoil karst.
1369	karst water	Water discharged from karst springs which posses characteristics, primarily that of calcium content, indicating solution during the passage of that water across and through karst limestone. That part of karst spring water which is derived from watercourses sinking into the rock (and therefore originates mainly on impermeable rock) is said to be allogenic; that which derives from precipitation over the karst area alone is said to be autochthonous - the distinction between resurgence and exsurgence waters [19].
1370	karst well	Term applied to features that result from the solution enlargement and rounding of joints (grikes) to produce cylindrical pits [8]. See also grike; joint.
1371	karst window	1. Depression revealing a part of a subterranean river flowing across its floor, or an unroofed part of a cave. 2. A small natural bridge or arch which can be seen through [10]. 3. A through opening in natural limestone walls, formed by the joining of karst grottos as a result of dissolution processes [20]. Synonyms: (French) fenêtre karstique; (German) Karstfenster; (Greek) karstikon parathyron; (Italian) finestra carsica; (Russian) karstovoe okno; (Spanish) dolina en ventana; (Turkish) karst penceresi; (Yugoslavian) krsko (krasko) okno.
1372	karstic	Occasionally used as the adjective form of karst [10] and pertaining to karst landforms or processes [19].
1373	karstification	1. The processes of solution and infiltration by water, mainly chemical but also mechanical, whereby the surface features and subterranean drainage network of a karstland are developed to form a karst topography, including such surface features as dolines, karren, and mogotes and such subsurface features as caves and shafts. An area currently or formerly undergoing karstification, and thus characterized by karst landforms, is said to be karstified [19]. 2. The process by which karst is formed. The term has been given a wide range of meaning, from almost a synonym or corrosion of soluble rocks by water to a term comprising all processes responsible for the development of karst features including, besides corrosion, such phenomena as mechanical erosion, jointing, and faulting [20]. Synonyms: (French) karstification; (German) Verkarstung; (Greek) apokarstosis; (Italian) carsificazione; (Russian) karstoobrazovanie; (Spanish) karstificación; (Turkish) karstlaşma; (Yugoslavian) okršavanje, zakrasevanje, karstifikacija.
1374	karstland	A region characterized by karst topography [10].
1375	Karstrandebene	(German) See karst margin plain.
1376	katavothron	(Greek) A closed depression or swallow hole [10].
1377	Kegelkarst	(German) A general term used to describe several types of tropical humid karst characterized by numerous, closely spaced cone-, hemispherical-, or tower-shaped hills having intervening closed depressions and narrow steep-walled karst valleys or passageways [10]. See also cockpit karst; cone karst; Halbkugelkarst; tower karst.
1378	keld	See rising.
1379	kernmantel rope	A rope with a plaited sheath around a core of parallel or twisted strands [25].
1380	krab	See carabiner.
1381	keyhole passage; keyhole	1. This very descriptive name derives from the cross-sectional shape of a cave passage that consists of a phreatic tube with a vadose canyon cut in its floor. It is the classic example of a two-phase cave passage that originated and began its development in the phreas and was then modified by vadose entrenchment. As this sequence is the result of water table lowering by normal surface erosion, keyholes are common. Some keyholes are so small that the lower slot is impassable and the caver has to squeeze along the upper tube; others are very large. Spectacularly long is the 5km of keyhole forming the Fissures in Castleguard Cave, Canada. A tube 6m in diameter tops an irregular tapering canyon 15m deep that must be traversed on sloping ledges at mid-level [9]. 2. A small passage or opening in a cave; in cross section, rounded at the top, constricted in the middle, and rectangular or flared out below [10]. They appear as keyholes when viewed in cross section. They are formed when underground streams flowing in a tubular passage begin downcutting to form a canyon passage [15]. See also canyon passage; passage; tubular passage; vertical shaft.
1382	klinkenberg effect	The slip of gas molecules at the pore wall giving apparently higher permeability than would be obtained by liquid measurements [16].
1383	Kluft	See aisle.
1384	Kluftkarren	(German) See grike.
1385	knobstone	Speleothem, larger, more pronounced, and more widely separated than cave coral [10].
1386	knots	Various methods of securing or tying ropes or webbing material together by cavers [13]. See also prusik knot; prusiking.
1387	kras; krš	A slavic word meaning bleak, waterless place, from which the term karst is derived [10]. See also karst.
1388	Kugelkarst	See Halbkugelkarst.
1389	kunker	See caliche.
1390	laboratory coefficient of permeability, standard coefficient of permeability	Permeability defined for controlled temperature conditions (60°F) as gallons per day per square foot (gpd/ft2) under a unit gradient [16]. See also Meinzer unit.
1391	labyrinth	See network; maze cave.
1392	lacustrine formation	A sedimentary formation of lacustrine origin.
1393	ladder	In caving, a flexible, lightweight ladder of galvanized or stainless steel wires and aluminium alloy rungs [25].
1394	lag time	A time lapse between the onset of a given event and the produced results [16].
1395	lagoon	A body of relatively shallow water near a sea shore, with or without a direct connection to the sea [16].
1396	lake	1. As used in speleology, a body of standing water too deep to walk across [10]. 2. In caving, a body of standing water in a cave, but used for what would be called a pond or pool on the surface [25]. 3. A body of fresh inland water [16].
1397	laminar flow	Flow in which the head loss is proportional to the first power of the velocity [22]. Water flowing in a laminar manner will have streamlines that remain distinct and the flow direction at every point remains unchanged with time. Synonymous with streamline flow, viscous flow.
1398	lamination	The layering or very thin bedding of sedimentary rocks [16].
1399	landfill	A general term indicating a disposal site for refuse, dirt from excavations, junk [6], and hazardous wastes.
1400	land-form	A topographic feature of the earth’s surface [16].
1401	land pan	An evaporation pan used to measure evaporation from a land surface; pan is usually mounted at the land surface [16].
1402	land subsidence	The subsidence of a surface due to a loss of support [16]. Often occurs as a result of over pumping underlying aquifers or as a result of mining activities. In karst terranes, subsidence can occur as a result of man-made changes to the natural hydrologic system (ground- water withdrawals or storm-water injection) or as a consequence of the natural dissolution process. Subsidences may be sudden or progress slowly over time.
1403	land surface	That part of the lithosphere usually not covered by water [16].
1404	land-use	A particular utilization of a land surface especially with respect to its influence on the hydrologic cycle [16].
1405	landslide	The sliding down of earth and rock on a slope [16].
1406	lapiés	(French; sometimes spelled lapies or lapiaz.) Term for a region with outcrops of small regular pillars, cones, or blocks of carbonate rock [20]. Synonyms: (French) lapies; (German) Karren; (Greek) lapiaz, lenar; (Italian) lapia, solcato, carregiato; (Russian) karri; (Spanish) lenar; (Turkish) erime oluğu, lapya; (Yugoslavian) škrapa, grižine, bridine, žlebici. See karren, rock-rill, grikes.
1407	larva (plural larvae)	An active immature stage in an animal’s life history when its form usually differs from the adult form, such as the grub stage in the development of a beetle or the tadpole stage in the life history of a frog [23]. See also metamorphosis; pupa.
1408	lateral line system	A series of sensory organs, usually appearing in a line or series of lines on the sides and heads of fishes and larval amphibians. The system enables the animal to sense vibrations in the water [23]. See also cupula; neuromast.
1409	lateral moraine	A glacial deposit at the flank of a glacier, often constituted by debris from valley walls [16].
1410	laterite	A tropical ferruginous clay soil [16].
1411	lateritic soil	A red colored soil with high iron oxide content [16].
1412	lava bed	A lava flow of considerable areal extent and relatively small thickness [16].
1413	lava cave, lava tube	1. A cave that formed in a partly cooled, broadly basaltic or phonolitic lava, not by erosion but by molten material flowing away. In most cases, an initial active lava conduit is formed when a flowing surface lava stream has a roof grow over it by accretion of chilled solidified material. Insulated inside its conduit the lava can continue to flow and develop an airspace above it, which is preserved as an explorable cave when completely cooled. Most lava caves are just very long tubes, though branching and multiple levels may occur as dictated by flow patterns and re-invasions of older tubes. On Kilauea Volcano, Hawaii, the Kazumura Cave is 47km long and descends 888m, but its tubes, mostly 5m in diameter, lie less than 20m beneath the sloping surface of the lava [9]. 2. A cave in a lava flow, generally formed by gas blistering the surface or by lava flowing out from beneath a solidified crust, forming a tube or tunnel [10]. 3. An empty tubular supply channel from which liquid lava has drained [16]. See also lava karst; pseudokarst.
1414	lava karst	A non-karst term. Subsurface openings formed in lava flows due to outflow of liquid lava from beneath a solidified crust or due to gas blisters. Tubes or tunnels are formed with such pseudokarst features as lava stalactites and also collapse structures and basins of closed drainage. Lava karst does not arise through solution of the rock by circulating water and thus is not a true karst [20]. Synonyms: (French) pseudo-karst; (German) (Vulkanischer Karst), Lava-Karst, Pseudokarst; (Greek) pseudokarst; (Italian) pseudocarsismo vulcanico; (Spanish) volcanokarst (general), tubo volcanico (tube, tunnel), jameo (collapse structure), malpaís (topographic feature similar to lapiés); (Turkish) lav karstı, a ldatıcı karst. See also lava cave; pseudokarst.
1415	lay	The way in which strands of a rope or cable are twisted [25].
1416	layer	A sheetlike deposit of sediment [16]. Bed or stratum of rock [16].
1417	leachate	1. Materials removed by the process of leaching [22]. 2. A liquid that has percolated through soil rock or waste and has extracted dissolved or suspended materials [22].
1418	leaching	1. The removal of materials in solution from soil, rock, or waste [22]. 2. Separation or dissolving out of soluble constituents from a porous medium by percolation of water [22].
1419	lead	A passage noticed but as yet unexplored [25].
1420	lead-acid cell	A rechargeable acid battery for use with an electric cap lamp [25].
1421	leader	In caving, the person directing the activities of a caving party, especially with regard to safety [25].
1422	leak	An opening in an aquiclude that permits penetration of water from other formations into the main aquifer [16].
1423	leakage	1. The flow of water from one hydrogeologic unit to another. The leakage may be natural, as through semi-impervious confining layer, or manmade, as through an uncased well [22]. 2. The natural loss of water from artificial structures as a result of hydrostatic pressure [22].
1424	leakage factor	The factor describing leakage flow into or out of a leaky aquifer [16].
1425	leakance	1. The ratio K’/b’, in which K’ and b’ are the vertical hydraulic conductivity and the thickness, respectively, of the confining beds [22]. 2. The rate of flow across a unit (horizontal) area of a semipervious layer into (or out of) an aquifer under one unit of head difference across this layer. Synonymous with coefficient of leakage [22].
1426	leaky aquifer	Aquifers, whether artesian or water-table, that lose or gain water through adjacent less permeable layers [22].
1427	lecontite	A cave mineral — (NH₄,K)Na(SO₄)·2H₂O [11].
1428	leg	A part of a survey traverse between two successive stations [25].
1429	leucophor	One of a family of optical brightening agents that have been used with some degree of success in water-tracing experiments. It has no color, but is readily detected by its distinctive fluorescence under ultra-violent light [9].
1430	levee	An artificial bank to prevent overbank flow of a river [16].
1431	level	1. Within a cave, a group of passages developed in the same horizontal plane [10]. 2. The altitudinal relation of a cave floor to an outside surface [10]. 3. The surface of water in a well or standing reservoir [16].
1432	lift	The vertical pumping distance between the water level in a well to the land surface [16].
1433	light hole	(Jamaican) 1. A hole in the roof of a cave through which light enters; sometimes a nonfunctioning swallow hole [20]. 2. Fossil or abandoned swallow hole [10].
1434	lime	Calcium oxide, CaO; used loosely and incorrectly in referring to limestone [10].
1435	lime sink	See sinkhole.
1436	limestone	Sedimentary rock containing at least 50% calcium carbonate by weight. The purer limestones consist almost entirely of calcite; less pure rocks may be referred to as, for example, muddy limestone. Some limestones are porous with diffuse permeability; these rarely become truly cavernous, though some fissure flow may occur. Where ground-water flow in less porous rocks is restricted to bedding related fissures and secondary fractures it can, even when moving very slowly, corrode the almost entirely soluble rock and lead to true cave development [9].
1437	limestone pavement	1. A level, or gently inclined, bare limestone surface scored and fretted by karren. The stripping of soil or cover rocks to expose the bare rock pavement is a glacial process, and the development of the karren — both the dissolutional enlargement of the joints and also the dissolutional carving of runnels — is largely post-glacial. Limestone pavements are characteristic features of glaciokarst and occur extensively in the north of England, in the Burren of County Clare in Ireland and on many high alpine limestones [9]. 2. A bare plane surface of limestone, parallel to the bedding, commonly divided into blocks (clints, Flachkarren) by solutionally widened joints (grikes, Kluftkarren), and pitted by solution pans [10]. 3. A glaciokarstic landform, produced on a glacially planed limestone surface which has subsequently become dissected into blocks (clints or dalles) by solution-enlargement of vertical joints [19]. 3. Horizontal or sloping platforms of bare limestone whose surface usually coincides with bedding- plane partings of the rock; often eroded into clint and grikes rock forms [20]. Synonyms: (French) plateforme calcaire; (German) Kalk Plattform, Limestone Pavement; (Greek) karstikon lithostroton; (Spanish) lapiaz entrecruzado; (Turkish) kireçtaşı döşemesi. See also clints; grikes; Karrenfeld.
1438	limestone sink	see sinkhole.
1439	limnology	The study of lakes [16].
1440	line of seepage	See seepage line.
1441	lineation	The parallel orientation of structural features that are lines rather than planes. Some examples are parallel orientation of the long dimensions of minerals, long axes of pebbles, striae on slickensides, and cleavage-bedding plane intersections.
1442	lintel line	A line on the ground at a cave entrance perpendicularly beneath the outer edge of the rock above; may or may not coincide with the dripline [25]. See also dripline.
1443	liquid	An incompressible or nearly incompressible fluid.
1444	liquid medium	Contains the aquatic cavernicoles [25].
1445	lithologic factor	The factor influencing composition, texture, and sequence of rock types [16].
1446	lithology	1. The physical characteristic of a rock, including composition, grain size, texture, degree of cementation (or lithification) and structure, that determine the rock type [9]. 2. The physical properties and aspect of a rock [16].
1447	lithosol	A rocky soil [16].
1448	lithosphere	That part of the earth’s crust containing solid rocks [16].
1449	lithostratigraphy	A formal naming system that allows the description of rock successions in terms of recognizable defined units on a local scale. The units, which comprise supergroups, groups, formations, members and beds in decreasing order of size, are described on the basis of observable characteristics [9].
1450	littoral zone	The coastal strip where rocks that are above sea-level are in contact with rocks that are generally below sea-level. Where suitable aquifer conditions occur across the littoral zone, notably around relatively young carbonate islands, fresh ground-water interfaces with saline ground-water at the halocline and dissolutional processes are enhanced by mixing water and, possibly, by microbial effects [9].
1451	live cave	Cave in which there is river action or active deposition of speleothems. Compare active cave [10].
1452	LNAPL	Abbreviation for light nonaqueous phase liquid. Liquids falling into this category have specific gravities that are less than water (the specific gravity for water is usually taken to be one), are relatively immiscible with water, and tend to migrate downwards through the vadose and to float on top of the water table. See also LNAPL; immiscible; NAPL.
1453	loam	Calcareous clay [16].
1454	localized circulation	Circulation in karst aquifers in which the water moves in certain preferred zones and does not occupy all or most of the openings below this level [10]. Synonyms: (French) circulation préfèrentielle; (German) Örtlich begrenzte Karstwaßer-Zirkulation; (Italian) circolazione carsica parziale; (Spanish) circulación localizada; (Turkish) yersel dolaşim; (Yugoslavian) lokalizirana (lokalna) cirkulacija. Compare diffuse circulation.
1455	lodgement till	Glacial till deposited from slowly melting ice at the base of a glacier [16].
1456	loess	Fine-grained and poorly consolidated windblown sediment, mainly of silt. Great thicknesses of loess are found in areas marginal to hot and cold deserts, where the prevailing wind deposits fine dust particles blown from the desert basins or out of glaciofluvial sediments. Loess is a common allogenic component of soils on limestones. Large numbers of artificial caves have been excavated in the hillsides of soft loess in central China [9].
1457	longitudinal fault	A fault having the same direction of strike as the surrounding strata [16].
1458	longitudinal section; long section	A section along the length of a cave passage or chamber or combination of these, or along a survey traverse in a cave [25].
1459	loosest packing	The three-dimensional arrangement of particles with the highest possible void volume per unit cell [16].
1460	losing stream	A stream or reach of a stream in which water flows from the stream bed into the ground [22]. In karst terranes, losing streams may slowly sink into fractures or completely disappear down a ponor. Synonym: influent stream. See also ponor; stream sink.
1461	lost circulation	The result of drilling fluid escaping from a borehole into the formation by way of crevices within the formation [6]. It is a common occurrence in most karst aquifers due to the existence of large subsurface voids that are sometimes intersected during a drilling program.
1462	lost river	1. A surface river or stream flowing onto or over karst that then disappears completely underground through a swallow hole (ponor) and which may or may not rise again and flow as a resurgent surface river or stream [20]. 2. In a karst region, a surface stream that enters an underground course [10]. Synonyms: (French) perte de rivière; (German) Flußversickerung, Flußchwinde; (Greek) chanomenos potamos; (Russian) iscezajuscaja reka; (Spanish) rio sumente; (Turkish) kayıp nehir; (Yugoslavian) ponornica, ponikalnica. See also ponornica; sinking stream. Compare intermittent river.
1463	lower confining bed	An impermeable bed underlying an aquifer [16].
1464	lower course	The part of a water course near a discharge point [16].
1465	low flow	The lowest sustaining flow during base runoff conditions of a river [16].
1466	Lycopodium spores	1. The spores of a club moss, with individual structures about 0.03mm in diameter. Easily transported by and almost indestructible in cave water, the spores can be dyed a variety of colors, and offer a valuable water-tracing technique. Preparation and collection of the spores is very tedious, and the method lacks the convenience of using simple dyes [9]. 2. Spores of Lycopodium clavatum, which can be used in natural or dyed color as a label in studying ground-water movement in karst areas [10].
1467	lysimeter	A device for measuring percolation and leaching losses from a column of soil under controlled conditions [22].
1468	Ma	Internationally accepted abbreviation for million years, commonly applied to measurements of geological time. This abbreviation is currently used in preference to My [9].
1469	macrokarst	Karst area with large morphological features. The term is not easily defined because it lacks limits [20]. Synonym; (Italian) merocarsismo. Compare microkarst.
1470	macropore	A pore with dimensions such that capillary forces become less important during flow [16].
1471	magnesian limestone	Common but loose synonym for dolomitic limestone or dolomite rock. The magnesian limestone of northern England is a rock sequence of Permian age that includes a locally variable number of beds of dolomitic limestone [9].
1472	magnesite	A cave mineral — MgCO₃ [11].
1473	magnetic north	The direction to the north magnetic pole at a given place and time. This differs from the direction towards which the north end of a compass points by a small individual compass error and by the effect of any local magnetic attraction [25].
1474	malachite	A cave mineral — Cu₂(CO₃)(OH)₂ [11].
1475	mammals	The class of animals that includes bats, mice, man, and many others. They typically have a body covering of hair and give birth to living young, which are nursed on milk from the mother’s breast [23].
1476	manatial	(Spanish) Spring. See also spring.
1477	Manning equation	An equation used to compute the velocity of uniform flow in open channel: V=1.486/n R^2/3 S^1/2 where V is the mean velocity of flow (in cfs units), R is the hydraulic radius in feet, S is the slope of the channel or sine of the slope angle, and n is the Manning roughness coefficient [1]. See also Chézy equation; Froude number; Reynolds number. [GP: This text under review.]
1478	manometer	A pressure measuring device for determining the hydraulic head developed by a flowing fluid [16].
1479	mantled karst	Karst topography that is wholly or partly covered by a relatively thin veneer of post-karst rock or sediment and is part of the contemporary landscape [17]. See also buried karst; covered karst.
1480	marble	1. Metamorphosed and recrystallized carbonate rock that is generally capable of supporting cave development. For example much of the Antro del Corchia in Italy and many caves in the South Nordland area of Norway have formed in marble [9]. 2. Limestone recrystallized and hardened by heat and pressure. 3. Commercially, any limestone that will take a high polish [10].
1481	marine relict	An animal whose presently extinct ancestors lived in salt water but became adapted to life in fresh water when an area formerly covered by the sea became dry land [23].
1482	marine water	Ocean water having invaded coastal aquifers [16].
1483	marginal polje	1. Flat plain surrounded by higher limestone country on all except one side which consists of impermeable ridges or hills. Such a feature is normally found on the edge of a karst area or region [20]. 2. Flat limestone plain which is surrounded by higher country but is bordered on one side by impervious rock [10]. Synonyms: (French) polje marginal; (German) Randpolje, Semipolje; (Greek) perithoriakón “polje”; (Italian) polje marginale; (Spanish) polje marginal; (Turkish) kenar gölova; (Yugoslavian) rubno polje, robno polje. See Randpolje. Compare blind valley.
1484	marker bed	A bed with characteristic features that can be followed over large areas for identification purposes [16].
1485	marl	Unconsolidated sedimentary rock consisting largely of calcium carbonate and clay; usage varies from calcareous clay to earthy limestone, and in some parts of the United States, the term has been used for any unconsolidated sedimentary rock containing fossil shells [10].
1486	mass curve	A graph of cumulative values of a hydrological quantity against time [16].
1487	mass density	Mass per unit volume of a substance [16].
1488	mass flowmeter	A measuring device for mass flow rates [16].
1489	massive structure	A homogenous structure without any oriented features [16].
1490	master cave	Best defined as a low level trunk streamway cave with many tributaries. The old concept of the master cave being formed at the water table should be disregarded. The Leck Fell Master Cave, in the Yorkshire Dales, is 2km long, partly a vadose canyon, partly a drained phreatic tube and partly a submerged tube. Part of it therefore lies below the water table while elsewhere its presence controls the water table. The French equivalent, “collecteur”, is more descriptive of the master cave’s true role. The depth to a currently active master cave is dictated by interactions between local topography, stratigraphical factors and geological structure. In the low hill karst of England and Kentucky, active master caves lie at depths of around 100m, but in Monte Canin, Italy, and the Hautla Plateau, Mexico, they lie at depths of 1000m. The collecteur of the Gouffre Berger, France, is met just 250m down but can be followed to a depth of over 1000m, down the dipping limestone beds, thus emphasizing the local dominance of stratigraphical over topographical factors [9].
1491	match point	A common point in the superposition of a type curve over measured data in aquifer test analyses.
1492	matric potential	The energy required to extract water from a porous medium to overcome the capillary and adsorptive forces [22].
1493	matrix	The solid framework of a porous system [22].
1494	maximum basin relief	The elevation difference between basin mouth and highest point within a basin perimeter [16].
1495	maze cave	A cave with an essentially horizontal network of interconnecting and mainly contemporaneous passage loops. Three broad types of maze cave have been described — anastomotic, network and spongework — and these may be subdivided on the basis of how they developed by slow-moving water, restricted to a confined, artesian aquifer, or by water that is ponded due to backflooding. A mechanism of potentially great importance, particularly in the context of the inception of network maze caves, is multiple, diffuse input from adjacent, permeable but non-cavernous rocks. Spectacular joint-guided maze caves such as Knock Fell Caverns and the Devis Hole Mine Caverns occur in the thin Yoredale limestones of the northern Pennines, but the most extensive mazes are in the Black Hills of Dakota, USA (including Jewel Cave) and in the Ukrainian gypsum karst (including Optimisticeskaja) [9]. See also maze cave pattern.
1496	maze cave pattern	A cave system which consists of a labyrinth of intersecting passages of rather uniform character that form closed loops. See also anastomotic cave pattern; maze cave; network cave pattern; spongework cave pattern.
1497	mean deviation	A linear mean of absolute deviations [16].
1498	mean value	The statistical average or measure of central tendency [16].
1499	meander	1. Overdeveloped and self-exaggerated bend is a stream course either on the surface or underground, caused by more erosion on the outside than on the inside of a bend due to natural wash of the flow. Undergound meanders commonly originate within bedding plane guided elements of the phreas, where a single dominant tube has gathered drainage from the surrounding area. Following uplift and the onset of vadose conditions any stream that utilizes the meandering tube incises rapidly and the imposed meander course is entrenched into the underlying rocks. Such incision or entrenchment produces characteristic tall, narrow, twisting vadose canyons, to such an extent that the French describe them as “meandres”. Canyons may meander more at their lower levels, due to enlargement during incision [9]. 2. A loop-like bend in a river due to lateral erosion activities [16]. 3. In a cave, an arcuate curve in a channel formed by lateral shifting of a cave stream [10]. See ceiling meander; meander niche.
1500	meander belt	A zone within which meandering of a stream occurs [16].
1501	meandering karren	These are small grooves cut directly into the rock surface, generally a few centimeters wide and deep. Their size remains the same or decreases downslope and usually exhibit small meanders with typical undercut slopes and slip-off slopes. They frequently appear in the bottom of larger grooves such as rinnenkarren [3]. See also wall karren; humus-water grooves. Synonym: (German) Mäanderkarren.
1502	meander niche	A conical or crescent-shaped opening in the wall of a cave, formed by the downward and lateral erosion of a stream on the floor of a passage [10].
1503	measuring flume	An artificial channel used for discharge measurements.
1504	measuring weir	A device used to measure flow rates indirectly through a weir head.
1505	mechanical ascender	A mechanical device that is the same as an ascender, but is used to clarify the use of a mechanical device instead of a rope ascender knot [13]. See also ascender.
1506	mechanical cover	A mechanical covering of a free water surface to prevent evaporation.
1507	mechanical dispersion	The process whereby solutes are mechanically mixed during advective transport caused by the velocity variations at the microscopic level. Synonymous with hydraulic dispersion [22].
1508	mechanical dispersion, coefficient	The component of mass transport flux of solutes caused by velocity variations at the microscopic level. Synonymous with convective diffusion [22].
1509	median	A value dividing frequency of varieties into two equal portions [16].
1510	medicinal spring	See spring, medicinal.
1511	medium sand	Grain particle with a diameter of 0.25 to 0.5 mm [16].
1512	Meinzer unit	A measure of hydraulic conductivity as gpd/ft2 under a unit hydraulic gradient [16].
1513	melanterite	A cave mineral — FeSO₄·7H₂O [11].
1514	melting	The passage from the solid to the liquid state due to temperature increases [16].
1515	melting point	The temperature at which a solid substance is transformed into its liquid state [16].
1516	meltwater	Water derived from the melting of snow pack or of a glacier [16].
1517	meniscus	A free surface or interface formed by liquid in a capillary tube [16].
1518	mercury column	A cylindrical bore in a manometer filled with mercury [16].
1519	mercury injection method	A measurement of porosity by mercury injection into a sample [16].
1520	merokarst	1. Defined by Cvijić to indicate imperfect karst topography as found on thin, impure, or chalky limestone where surface drainage and dry valleys are present in addition to some karstic features [10]. 2. Karst developed in soluble rocks retaining considerable surface drainage. Synonyms: (French) merokarst; (Turkish) yarı karst. Contrast perfectly formed Holokarst. Compare causse.
1521	mesh	1. An opening in a sieve screen [16]. 2. Number of openings per inch [16].
1522	mesophyte	A plant growing under intermediate moisture conditions [16].
1523	metabolic rate	The rate at which a living thing transforms food into energy and body tissue. The higher its metabolic rate, the more food it must consume. Most cave animals live at a reduced metabolic rate [23].
1524	metabolism	The sum of the chemical activities taking place in the cells of a living thing; the sum of the processes by which a living thing transforms food into energy and living tissue [23].
1525	metamorphosis	A change in the form of a living thing as it matures, especially the drastic transformation from a larva to an adult [23]. See also pupa.
1526	meteoric water	Water recently involved in atmospheric circulation [16].
1527	meteorology	The science dealing with all physical phenomena occurring in the atmosphere [16].
1528	mexican onyx	See onyx marble.
1529	micrite	A microscopic texture. An abbreviation of “microcrystalline calcite ooze” which refers to precipitated finely crystalline carbonate sediments in grains from 1 to 4 microns in diameter [20]. Synonyms: (French) micrite; (Greek) micrite; (Italian) micrite; (Spanish) micrita; (Turkish) mikrit; (Yugoslavian) mikrit. See biomicrite, peloid.
1530	microclimate	“Little climate.” The environmental conditions, such as temperature; humidity, and air movement, in a very restricted area, such as a sheltered nook in a cave wall [23].
1531	microgour	Miniature rimstone dams with associated tiny pools of the order of 1cm wide and deep on flowstone [25].
1532	microhabitat	A miniature habitat within a larger one; a restricted area where environmental conditions differ from those in the surrounding area. A sheltered nook in a cave wall is an example of a microhabitat within the cave [23].
1533	microkarren	Very small dissolutional channels, commonly 1–3mm across; parallel, convergent or randomly intersecting on a limestone surface. Though found in all climatic regions they are most conspicuous in semi-arid and periglacial environments, where dissolutional processes are minimal and very slow. The random patterns of some microkarren may be due to the effects of condensation water [9].
1534	microkarst	1. Karst area with small morphological features. Term is not easily applied because it lacks limits [20]. 2. Karst topography in which all surficial features are small; an area dominated by minor karst features [10]. Compare macrokarst.
1535	microspar	A microscopic texture. Mosaic of tiny (4 to 10 micron diameters) clear calcite crystal [20]. Synonyms: (French) microsparite; (Greek) mikrosparítis (mikroskopikón, mosaikón kristállon); (Italian) microsparite; (Spanish) microesparita; (Turkish) mikrospar.
1536	middens	Accumulations of animal droppings other than guano and often found in caves; may be solidified [13]. See also cave guano; guano cave; coprolite.
1537	migration	The movement of water, contaminants, or other fluids in the geologic substratum, mostly by natural causes [16].
1538	mine drainage	Waters coming from or passing through surface or subsurface mine workings [16].
1539	mine water	Water accumulating in a mine.
1540	minerals	Mineral components of a rock, often in macrocrystalline form [16].
1541	mineral spring	See spring, mineral.
1542	mining of ground water	The permanent depletion of ground-water reserves [16].
1543	minor karst features	See karren; rill; solution pan.
1544	mirabilite	The natural white mineral form of hydrated sodium sulfate, Na₂SO₄·10H₂O [9], which may grow as cave flowers or in various other forms similar to those of gypsum.
1545	Mischungskorrosion	(German) Dissolution of calcite (and hence of limestone) by ground water that is derived from the mixing of two different waters that were originally saturated with carbon dioxide but had reached saturation under differing carbon dioxide partial pressures. The resultant mixture is undersaturated and capable of further calcite dissolution, because the relationship between calcite solubility and carbon dioxide partial pressure is non-linear [9].
1546	miscible	1. Two or more liquids that are mutually soluble (i.e. they will dissolve in each other [22]. 2. The chemical property of two or more phases that, when brought together, have the ability to mix and form one phase [22].
1547	miscible displacement	1. The mutual mixing and movement of two fluids that are soluble in each other [22]. 2. The displacement of a fluid saturating a porous medium by another fluid completely miscible with the first fluid [16]. Synonymous with miscible-phase displacement.
1548	mixing length	The length over which mixing occurs, especially of momentum in turbulent flow [16].
1549	mixture corrosion	See Mischungskorrosion.
1550	mode	The most frequently occurring variate in a frequency distribution [16].
1551	model	1. A conceptual, mathematical, or physical system obeying certain specified conditions, whose behavior is used to understand the physical system to which it is analogous in someway [22]. 2. A conceptual description and the associated mathematical representation of a system, subsystem, components, or condition that is used to predict chances from a baseline state as a function of internal and/or external stimuli and as a function of time and space [22]. 3. A simplified system bearing some physical similarity to a prototype [16].
1552	model technique	A method of solving complex physical problems through the application of simplified models [16].
1553	mogote	A steep-sided hill of limestone, generally surrounded by nearly flat alluviated plains: karst inselberg. Originally used in Cuba in referring to residual hills of folded limestone in the Sierra de los Organos but now used internationally for karst residual hills in the Tropics [10]. Differs from cone, cupola, pinnacle and tower karst in its shape which reflects its karstification history [20]. Synonyms: (French) mogote; (German) (Karstinselberg), Mogote; (Greek) “moghotis” (apókrimnos, asvestólofos perikliómenos apó proschomatikas pediadas); (Italian) mogote, rilievo carsico residuo; (Spanish) mogote; (Turkish) karst kalıntı tepesi; (Yugoslavian) hum. See also hum; karst inselberg; pepino hill.
1554	moisture content	1. The ratio; expressed as a percentage, of either (a) the weight of water to the weight of solid particles expressed as moisture weight percentage or (b) the volume of water to the volume of solid particles expressed as moisture volume percentage in a given volume of porous medium [22]. 2. The gravimetric water vapor content of air [16]. See also water content.
1555	moisture deficiency	The quantity of water required to restore moisture to field capacity in a desiccated soil [16].
1556	moisture equivalent	The percentage of water retained in a soil sample 1 cm thick after it has been saturated and subjected to a centrifugal force 1000 times gravity for 30 min. Centrifuge moisture equivalent is the water content of a soil after it has been saturated with water and then subjected for 1 hour to a force equal to 1000 times that of gravity [22].
1557	moisture tension	The equivalent negative pressure of water in an unsaturated porous medium equal to the pressure that must be applied to the medium to bring the water to hydraulic equilibrium through a porous permeable material with a pool of water of the same composition. Synonym: capillary tension [22].
1558	moisture volume percentage	The ratio of the volume of water in a soil to the total bulk volume of the soil [22].
1559	moisture weight percentage	The moisture content expressed as a percentage of the oven-dry weight of a soil [22].
1560	mold	A microscopic form of fungus responsible for much food spoilage and, in caves, for conspicuous tufts quickly covering scats, dead insects and bats, and even wooden structures such as ladders [23].
1561	molecular diffusion (diffusion.)	The process whereby solutes are transported at the microscopic level due to variations in the solute concentrations within the fluid phases [22]. The kinetic energy generated by the transport of ionic or molecular constituents results in some dispersion of a chemical.
1562	molecular diffusion, coefficient of	The component of mass transport flux of solutes (at the microscopic level) due to variations in solute concentrations within the fluid phases. Synonymous with diffusion coefficient [22].
1563	molecule	A stable configuration of atomic nuclei and electrons bound together by electrostatic and electromagnetic forces. It is the simplest structural unit that displays the characteristic physical and chemical properties of a compound [6].
1564	mollisol	A soil layer subject annual thawing and freezing, often becoming mobile upon thawing [16].
1565	monetite	A cave mineral — CaHPO₄ [11].
1566	monohydrocalcite	A cave mineral — CaCO₃·H₂O [11].
1567	monomolecular film	A layer of monomolecular thickness of a polar substance spread over a free water surface to prevent evaporation.
1568	montgomeryite	A cave mineral — Ca₄MgAl₄(PO₄)₆(OH)₄·12H₂O [11].
1569	montmorillonite	A clay mineral containing magnesium oxide (MgO) in its structure [16].
1570	moonmilk	1. A white plastic calcareous cave deposit composed of calcite, huntite, or magnesite. From Swiss dialect moonmilch, elf’s milk. Corrupt spelling mondmilch is common [10]. 2. Deposits consisting mainly of very fine particles of calcium and magnesium carbonate precipitated from water in caves and caverns. When in suspension, they give the water the appearance of milk. Name originated in 1714 by M. B. Valentini (Fénelon) [20]. 3. Moonmilk consists of a variety of hydrocarbonates some of which are associated with particular species of bacteria. A common mineral in moonmilk from temperate caves is hydromagnesite; cold caves yield moonmilk of calcite after hydrocalcite [20]. Synonyms: (French) mondmilch; (German) Bergmilch, Montmilch; (Greek) speleogala; (Italian) latte di monte; (Russian) kamennce moloko; (Spanish) mondmilch, leche de luna; (Turkish) dik karstik kalıntı; (Yugoslavian) gorsko mlijeko (mleko). Also mountain milk.
1571	moor	A wet peat bog [16].
1572	moulin	The French word for “mill”, moulin, has been used to describe partially dissolutional, partially scoured pockets cut in rock, particularly the potholes formed in the beds of surface and underground streams. In some areas sinkholes in the surface of glaciers, which may provide access to glacier caves, are also referred to as moulins [9].
1573	mountain milk	See moonmilk.
1574	moraine	A mound, ridge, or other distinct accumulation of unsorted, unstratified glacial drift, predominantly till, deposited chiefly by direct action of glacier ice [6].
1575	morphometric analysis	A geodetic and geometric description of basin and stream network or to a sinkhole plain [16].
1576	mud	Water saturated fine clayey earth material [16].
1577	mud crack	Desiccation cracks appearing in drying mud surfaces due to shrinkage [16].
1578	mud pendulite	A pendulite with the knob coated in mud [25].
1579	mud stalagmite	1. Stalagmitic column made of mud or clay with about 30% calcium carbonate cement. There may be some coarse noncalcareous detritus in the core of such a column [20]. 2. Stalagmite composed principally of clay or sandy clay and commonly less than 30% calcium carbonate [10]. Synonyms: (French) stalagmite d’argile; (German) Stalagmit aus Tonschlamm; (Greek) pilostagmitis; (Italian) stalagmite di fango; (Spanish) ostalagmita de barro; (Turkish) çamur dikiti. Related to stalagmite.
1580	mudflow	A flow of water saturated unconsolidated debris [16].
1581	multiaquifer formation	A formation with several aquifers overlying each other [16].
1582	multiaquifer well	A well completed and tapping several aquifers [16].
1583	mutation	A sudden change in the genetic material of an organism’s germ cells, resulting in offspring that possess characteristics markedly different from those of either parent. Mutations generally are harmful, but occasionally may improve an organism’s chances for survival [23]. See also adaptation; evolution.
1584	My	See Ma.
1585	Nackter karst	(German) See exposed karst.
1586	Nacktkarst	(German) See exposed karst.
1587	naked karst, bare karst	Karst topography developed beneath a temporary cover. Some naked karsts develop beneath a temporary cover of snow (nival karst) or water [17]. Synonyms: (French) karst nu; (German) oberflächlicher nackter Karst; (Greek) gymnon karst; (Italian) carso nudo; (Russian) golyĭ karst or otkrytyĭ karst; (Spanish) karst desnudo; (Turkish) çıplak karst; (Yugoslavian) goli krš. See also exposed karst.
1588	NAPL	Abbreviation for nonaqueous phase liquid. This term is used to describe the physico- chemical that exist between a bulk hydrocarbon and water which results in the two liquids being immiscible with one another (i.e. little or no mixing of the two liquids occurs.) The interface is a physical dividing surface between the bulk phases of the two liquids. NAPLs are divided into two categories; LNAPLs and DNAPLs. See also DNAPL; immiscible; LNAPL.
1589	nari	Term used in the countries bordering the Eastern Mediterranean for caliche or hardpan [20]. See caliche, sabath.
1590	narrow	A passage of restricted width between two caves or hollows in the karst underground; often not readily traversable [20]. Synonyms: (French) étroiture; (German) Enge; (Greek) steno perasma; (Italian) strettoia; (Russian) laz; (Spanish) laminador, gatera; (Turkish) ağiz geçit; (Yugoslavian) sutjeska, klisura, soteska.
1591	native ground water	Original ground water [16].
1592	natural arch	1. A residual portion of the roof of a subsurface karst cavity which has not collapsed. Such a natural arch may occur as a surface topographic feature, or as a part of a cave system [20]. 2. A rock arch or very short natural tunnel; contrasted with natural bridge, which spans a ravine or valley [10]. Synonyms: (French) arche naturelle; (German) natürlisches Gewölbe, Naturbrücke, Felsfenster, Felsbrücke; (Greek) physike apsitha; (Italian) arco naturale; (Russian) estestvennij arka; (Spanish) arco natural; (Turkish) dogal kemer; (Yugoslavian) prirodni svod, luk, naravni obok. See also natural bridge.
1593	natural bridge	1. A residual portion of the roof of a subterranean stream which has not collapsed and is found bridging a valley. Normally a surface feature, but may be used to describe a similar occurrence in a cave system [20]. 2. A rock bridge spanning a ravine and not yet eroded away [10]. Synonyms: (French) pont naturel; (German) Naturbrücke, Felsbrücke; (Greek) physiki gefyra; (Italian) ponte naturale; (Russian) estestvennij most; (Spanish) puente natural; (Turkish) dogal köprü; (Yugoslavian) prirodni most, naravni most. See also natural arch.
1594	natural levee	A river bank raised by the river’s own depositions [16].
1595	natural load	Sediment carried by a stable stream [16].
1596	natural tunnel	A nearly horizontal cave open at both ends, generally fairly straight in direction and fairly uniform in cross section [10].
1597	natural water	Water with a mineral content occurring under natural conditions.
1598	natural well	(Jamaican) A vertical shaft in limestone, open to the surface and having water at the bottom; similar to a cenote [10]. Synonym: (Italian) pozzo carsico.
1599	neck	A volcanic pipe filled with lava [16].
1600	necrophage	A scavenger feeding on animal carcasses (not prey) [25].
1601	neomorphism	A microscopic texture. A complex of processes whereby a mosaic of finely crystalline carbonate is replaced by a coarser (sparry) mosaic without the development of visible porosity. Dominant reactions are the wet transformation of aragonite to calcite and recrystallization. The process is “porphyroid” where some of the neomorphic crystals are conspicuously larger than those which surround them [20]. Synonyms: (French) néomorphisme; (German) Neomorphismus ?; (Greek) neomorphismós; (Spanish) neomorfismo; (Turkish) neomorfizm.
1602	neoteny	The condition of retaining larval form and behavior even as a mature individual. Certain salamanders in particular are neotenic [23].
1603	neptunian deposits	Younger sediment or sedimentary rock that infills pre-existing cavities, such as grikes, dolines or cave passages, in older rocks. The most common form is a fissure fill, known as a neptunian dike. Neptunian deposits occupy voids in non-karstic as well as karstic rocks, and the combination of void and fill may subsequently be buried by still younger rocks. They may thus become part of a paleokarst [9].
1604	nesquehonite	A cave mineral — Mg(HCO₃)(OH)·2H₂O [11].
1605	nested sinkholes	(American) See uvala.
1606	net radiation	The sum of incident and reflected sun and sky shortwave radiation plus incident and reflected atmospheric long-wave radiation [16].
1607	network cave pattern	A type of maze cave characterized by a complex pattern of repeatedly connected passages in a cave system. In map view, this type of maze cave appears similar to a city street map. It is typically formed by solutionally aggressive water infiltrating through fractures in an overlying insoluble cap-rock thus exhibiting a joint-controlled pattern. Synonym: labyrinth.
1608	neutrality point	The separation point between acid and basic solution with a pH of 7.0 [16].
1609	neuromast	One of the individual sense organs that make up the lateral line systems of fishes and amphibians [23]. See also cupula.
1610	nife cell	A rechargeable alkaline battery for use with an electric-cap lamp [25].
1611	nip	An undercutting notch in rock, particularly limestone, along a seacoast between high and low tide levels along sea coasts and produced by solution and erosion. Most common along coasts with limited tidal variation [20]. Synonyms: (French) resserrement, étranglement; (German) Kliff ?, Brandungsmarke; (Greek) káto engopí vráchou; (Italian) solco di battigia; (Spanish) socavación marina; (Turkish) dalga yarıgı çentigi.
1612	nis̃a	See aisle.
1613	niter	A white orthorhombic mineral — KNO₃. It is a soluble crystalline salt that occurs as a product of nitrification in most arable soils in hot, dry regions, and in the loose earth forming the floors of some natural caves [1]. Synonyms: saltpeter; potassium nitrate.
1614	nitrammite	A cave mineral — NH₄NO₃ [11].
1615	nitrocalcite	A cave mineral — Ca(NO₃)₂·4H₂O [11].
1616	nitromagnesite	A cave mineral — Mg(NO₃)₂·6H₂O [11].
1617	nival karst	Alpine karst [1].
1618	nivo-karst	A karst-like topography produced by the differential chemical weathering beneath snowbanks from snowmelt containing carbonic acid. It is found mostly in periglacial areas [1].
1619	node point	The intersection point on a grid [16].
1620	nodule	A small, irregularly rounded knot, mass, or lump of a mineral or mineral aggregate, normally having a warty or knobby surface and no internal structure, and usually exhibiting a contrasting composition from the enclosing sediment or rock matrix in which it is embedded (e.g. a chert nodule in limestone.) Most nodules appear to be secondary structures in sedimentary rocks they are primarily the result of post depositional replacement of the rock and are commonly elongated parallel to the bedding. Nodules can be separated as discrete masses from the host material [1].
1621	noethphreatic flow	A type of conduit flow that is always laminar [9].
1622	nominal	Used to describe standard sizes for pipe from 1/8 inch to 12 inches (3.2 mm to 304 mm.) The nominal size is specified on the basis of the inside diameter. Depending on the wall thickness, the inside diameter may be less than or greater than the number indicated [6].
1623	nongraded	An engineering term pertaining to a soil or an unconsolidated sediment consisting of particles of essentially the same size [6].
1624	non-point source	1. Any source, other than a point source, which discharges pollutants into air or water [22]. 2. Source originating over broad areas, such as areas of fertilizer and pesticide application and leaking sewer systems, rather than from discrete points [22].
1625	non-recording gage	A standard rain gage (8 is standard in U.S.) [16].
1626	normal depth	The depth at which uniform flow occurs in an open channel [16].
1627	normal fault	A fault in which the upper block appears to have moved downward relative to the lower block.
1628	Northing	1. The distance of a point north of the point of origin of the grid of a map, or some abbreviation of it. 2. The south-north component of a survey leg, or of a series of legs, or of a complete traverse; north is positive and south is negative [25].
1629	nothephreatic	Referring to water moving slowly in cavities in the phreatic zone [25].
1630	numbering	Assigning an alphanumeric index to a cave entrance [25].
1631	oasis	A limited area in a desert supplied with water [16].
1632	obruk	Turkish term for a vertical or steepsided depression or shaft in karst, often formed by collapse of roof of an underground cave or cavern. When the depression contains a lake of pond, it is known as “sulu obruk” or “obruk gölü”. When it is dry, it is called “kuru obruk” or just “obruk”. Synonyms: (French) obruk; (German) Schlot; (Greek) “obruk” (káthetos karstikós lákkos); (Italian) pozzo carsico; (Spanish) torca; (Turkish) obruk; (Yugoslavian) jama. See cenote, dolina, jama, pit, shaft, sinkhole.
1633	obsequent river	A river flowing in a direction opposite to that of the dip of the underlying strata [16].
1634	observation well	A well drilled for the purpose of observations such as water level or pressure recordings [16].
1635	oceanic water	Sea water with a total salt content of about 34,500 ppm [16].
1636	ojo, ojo de agua	(Spanish) An artesian spring in limestone regions, especially one forming a small pond; a vauclusian spring [10].
1637	olivenite	A cave mineral — Cu₂(AsO₄)(OH) [11].
1638	omnivore	An animal that habitually eats both plants and animals [23]. See also carnivore; herbivore; insectivore.
1639	onyx marble	Translucent layers of calcium carbonate from cave deposits, often called Mexican onyx or cave onyx; used as an ornamental stone [10].
1640	oolite	A type of limestone that is composed largely or partly of ooliths. Also known as oolitic limestone. The best known examples in Britain, within the Jurassic limestone sequence of the Cotswolds, are of only moderate strength, very porous and only weakly cavernous. In contrast, oolites of early Carboniferous age have hosted extensive cave development beneath Mymydd Llangattwg and in other parts of South Wales [9].
1641	oolith	A small ovoid to spherical accretionary particle, usually composed of concentric layers of calcium carbonate. Such ooliths, cemented together by calcium carbonate, iron salts or other minerals, are the major constituent of oolite or oolitic limestone [9].
1642	oolitic	Of spherical or ovoidal shape [16].
1643	opal	A cave mineral — SiO₂·nH₂O [11].
1644	open system	A system where matter and energy may cross a system boundary [16].
1645	open traverse	A traverse which does not close onto a survey point of known coordinates and orientation or onto itself [25].
1646	Opferkessel	See solution pan.
1647	optical brighteners	Material contained in laundry detergents to make “whites whiter” and used in environmental tracing studies. Common types are, Tinopal CBS-X, Tinopal 5BM GX, and Phorwite BBH Pure. Dye type: Stilbene. See also fluorescent dyes.
1648	ore karst	Formation of interstices, caverns caves and other karst forms produced by solution in water from thermal springs and ore-bearing solutions [20]. Synonyms: (French) karst minier; (German) Zwischenräume, Kavernen, Höhlen im Karst, gebildet durch Thermalwässer oder erzhaltige Lösungen; (Greek) thermometallikon karst; (Italian) carsismo per dissoluzione idrotermale; (Russian) rudnij karst; (Spanish) karst termomineral; (Turkish) cevher karstı; (Yugoslavian) rudni krs̃ (kras).
1649	organic	Pertaining to anything that is or ever was alive or produced by a living plant or animal. Organic material brought into the cave from outside is virtually the only source of food for cave dwellers [23].
1650	organic deposit	Deposits of calcareous and siliceous remains of animals [16].
1651	organic pollution	Contamination originating from organic sources [16].
1652	orientation	1. The assignment or imposition of a definite direction in space; the act of establishing the correct relationship in direction, usually with reference to the points of the compass. Also, the of being in such relationship. 2. In describing crystal form and symmetry, the placing of the crystal so that its crystallographic axes are in the conventional position. 3. The direction in which an aerial photograph is turned with respect to observer or map. A single photo is best oriented for study when turned so that the shadows are cast toward the observer. 4. Directional arrangement of nonspherical grains in a sand aggregate [16].
1653	original dip	Dip due to deposition of sediments [16].
1654	original interstice	Interstice formed during rock formation stage [16].
1655	orographic precipitation	Precipitation due to mechanical lifting of air over a ground relief [16].
1656	orthogonal	Perpendicular.
1657	otkryĭ karst	(Russian) See naked karst.
1658	oulopholite	See cave flower.
1659	outcrop	An open exposure of bedrock or otherwise buried material [16].
1660	outflow cave	Cave from which stream flows out or formerly did so [10]. Synonym: effluent cave.
1661	outlet cave	A cave developed at the point of re-emergence of an underground karst watercourse [19].
1662	output point	A point where water exists from an underground drainage route or aquifer. An obvious output point is a surface resurgence or exsurgence, where drainage emerges from a conduit system. Less obvious are points where drainage leaves a carbonate aquifer and enters an adjacent non-carbonate bed, such as a sandstone aquifer [9].
1663	outwash	Stratified sand and gravel removed or washed out from a glacier by meltwater streams and deposited in front of or beyond the end moraine or the margin of an active glacier. The coarser material is deposited nearer to the ice [6].
1664	outwash gravel	Glacial drift material deposited by streams from a glacier [16].
1665	outwash plain	Plain in front of a glacier that is composed of outwash material [16]. A broad, gently sloping sheet of outwash [6].
1666	ouvala	(French) See uvala.
1667	oven-dry	The degree of dryness of a porous sample after drying in an oven at a specified temperature [16].
1668	overbank area	An area covered by flood waters overtopping natural or artificial river banks [16].
1669	overburden	1. The loose soil, sand, silt, or clay that overlies bedrock. In some usages it refers to all material overlying the point of interest. 2. The total cover of soil and rock overlying an underground excavation.
1670	overburden pressure	The pressure exerted by weight of the overburden column [16].
1671	overflow spring	See spring, overflow.
1672	overland flow	Surface runoff flowing over the land surface towards a channel [16].
1673	overthrust	Upthrust fault with a very low angle of dip and a relatively large net displacement [16].
1674	oxbow	Abandoned loop of a stream course, Original usage, applied to surface rivers, describes short-circuited meander loops but in caves the term is applied to dry loop passages of any shape and origin [9].
1675	oxidation	The combining of an element with oxygen [6].
1676	oxygen demand	The ability of substances to utilize dissolved oxygen in water.
1677	packing	The three-dimensional arrangement of particles [16].
1678	pahoehoe	(Hawaiian) Lava flows with a smooth or billowy surface in which lava tubes are found [13]. See also lava cave; pseudokarst.
1679	paleokarst	1. A karstified rock or area that has been buried by later sediments; in some places, ancient caves have been completely filled by the later sediments [10]. 2. A decoupled contemporary system that has experienced tectonic subsidence and lie unconformably beneath clastic cover rocks, occasionally becoming exhumed and re-integrated into the active system [17]. 3. A karst formed in the past under an earlier erosion cycle and often in remote geological times. The karst is preserved by burial or suspension of karstification processes [20]. 4. A karstified surface and the karst features associated with it, such as caves, that have been buried by younger rocks. Paleokarstic features at various scales may be recognized within most carbonate successions. More rarely they may be re-exposed (exhumed) by the effects of later uplift and erosion [9]. Synonyms: (French) paléokarst; (German) Paläokarst, foßiler Karst; (Greek) paleokarst; (Italian) paleocarsismo, carsismo fossile; (Russian) paleokarst; (Spanish) paleokarst; (Turkish) eski karst; (Yugoslavian) paleokrś, paleokras, paleokarst. See also buried karst.
1680	paleokarstic surface	A surface, preserved within a carbonate succession, that was formed by the effects of karst erosion. The presence of a paleokarstic surface indicates that during the deposition of the full rock sequence the young rocks were exposed to the effects of surface (sub- aerial) erosion. During such a non-depositional and erosional phase a full suite of karst features, including caves, could develop [9].
1681	paleomagnetism	Natural remanent magnetization preserved in rock sequences. During rock deposition magnetic minerals are aligned according to the direction and polarity of the earth’s contemporary magnetic field. After movement of the magnetic poles, or periodic reversals of polarity, the remanent magnetization is preserved in the rocks and may be measured to aid identification of stratigraphical units and to assess their relative ages [9].
1682	paleontology	The study of life in past geologic time, based fossil plants and animals and including phylogeny, their relationships to existing plants, animals, and environments, and the chronology of the Earth’s history [1].
1683	palette	In a cave, a more or less flat protruding sheet of crystalline calcium carbonate spared during solution of the rock on each side of it [10]. See also blade; shield. Synonym: shield.
1684	palygorskite	A cave mineral — (Mg,Al)₂Si₄O₁₀(OH)·4H₂O [11].
1685	pan coefficient	Coefficient to correlate a high rate of evaporation in a pan to an evaporation rate from larger water bodies [16].
1686	panhole	See solution pan.
1687	paragenesis	A type of cave passage development in which erosion of the passage floor is inhibited by the presence of an armoring layer of sediment, such that any dissolutional enlargement is dominantly upwards [9]. Generally, an unproven and unsupported theory.
1688	paragenetic cave	Cave passage, usually of canyon form, believed to be created by paragenesis. Passage formation by paragenesis is normally very difficult to prove, as later sediment removal leaves a passage that looks very similar to the far more common vadose canyon. It is thought that some of the larger canyons in the Flint Mammoth Cave System, USA, may have formed in this way [9].
2700	parahopeite	A cave mineral — Zn₃(PO₄)₂·4H₂O [11].
1689	paraphreatic	A paraphreatic passage has an air surface under relatively low flow conditions, when drainage is within the capacity of its downstream continuation, but reverts to being water- filled (phreatic) under conditions of high flow or when the downstream drainage is temporarily impeded [9].
1690	parent material	Material from which soil or sediment was formed [16].
1691	parietal fauna	Pertaining to the inhabitants on the walls of the entrance and twilight zones of a cave [23].
1692	park	(Arizona) Shallow broad solution depression [10].
1693	particle	The smallest individual constituent of an aggregate [16].
1694	particulate transport	The movement of particles in subsurface water [22].
1695	parting	The separation of sedimentary rock along bedding planes [16]. Synonyms: bedding-plane; bedding-plane parting. See also bedding plane.
1696	partition	1. A nearly vertical residual rock mass in a cave. 2. A continuous rock span across a cave [10].
1697	partitioning function	A mathematical relation describing the distribution of a reactive solute between solution and other phases [22].
1698	parts per million	An expression of concentration (ppm.) The weight per weight of a solution [16].
1699	passage	1. Broadly, a passage is any negotiable part of cave system, though the usage is commonly restricted to those elements that tend towards the horizontal rather than vertical or sub-vertical sections. Cave passages very in size and shape, with the latter relating to the mode of origin and providing evidence of the nature of cave development mechanisms. Perhaps the largest passage in the world is Deer Cave, which is up to 170m wide and 120m high, in the Mulu karst of Sarawak [9]. 2. A comparatively small underground opening made along fractures, fissures, and bedding-plane partings by running water but through which it is possible to pass [20]. 3. In a cave, the opening between rooms or chambers [10]. Synonyms: (French) galerie; (German) Gallerie, Stollen; (Greek) ypohios thiothos; (Italian) cunicolo, galleria; (Russian) hod; (Spanish) galeria; (Turkish) geçit; (Yugoslavian) galerija. See also chamber; room.
1700	pathogenic bacteria	Disease inducing bacteria [16].
1701	pavement	See limestone pavement.
1702	peat	Decomposed matter, mainly vegetable [16].
1703	pebble	A smooth rounded rock fragment [16].
1704	Péclet number	1. measure of the relative contribution of mechanical dispersion and diffusion to solute transport. It relates the effectiveness of mass transport by advection to the effectiveness of mass transport by either dispersion or diffusion . Péclet numbers below ≈0.4 indicate diffusion/dispersion control; 0.4–6.0 suggest that diffusion/dispersion and advection are in transition and thus approximately equal to each other; and >6.0 indicate advection control. Large Péclet numbers indicate strongly advective systems. 2. A relationship between the advective and diffusive components of solute transport expressed as the ratio of the product of the average interstitial velocity, times the characteristic length, divided by the coefficient of molecular diffusion. Small values indicate diffusion dominance, large values indicate advection dominance [22].
1705	pearl	See cave pearl.
1706	pediment	An inclined erosion surface covered with thin fluvial deposits [16].
1707	pendulite	A kind of stalactite which has been partly submerged [25]. and the submerged part covered with dog-tooth spar to give the appearance of a drumstick.
1708	pellicular water	1. The film of water left around each grain or fracture surface of water-bearing material after gravity drainage [22]. 2. Water of-adhesion [22]. 3. Water that can be extracted by root absorption and evaporation but cannot be moved by gravity or by the unbalanced film forces resulting from localized evaporation and transpiration [22].
1709	peloid	A microscopic texture. A sedimentary grain composed of micrite carbonate irrespective of origin [20]. Synonyms: (French) peloïde; (German) mikroskopisches, sedimentäres Gefüge; (Greek) piloidís; (Italian) peloide; (Spanish) peloide; (Turkish) peloit. See micrite, pelsparite.
1710	pelsparite	A microscopic texture. A limestone composed of pellets (peloids) in a matrix of cement [20]. Synonyms: (French) pelsparite; (German) Pelsarite, Kalkstein gefügt aus Kügelchen ?; (Greek) pelsparítis; (Italian) pelsparite; (Spanish) pelsparita; (Turkish) pelsparit. See peloids.
1711	pendant, rock pendant	One of a group of isolated similarly proportioned projections surrounded by a complex of connected cavities in the bedrock ceiling of a cave [10]. Formed by the rapid, differential solution of the surrounding rock [19].
1712	pendular regime	A saturation regime where a porous medium has the lowest possible saturation in the form of pendular rings at grain contacts [16].
1713	peneplain	A degradation surface without relief [16].
1714	pen trace	Ink, magnetic, or photographic line traced on the drum of a recording gage or meter [16].
1715	pepino hill	(Puerto Rican.) 1. Rounded or conical-shaped hill resulting from tropical humid karst action. Term generally replaced in Puerto Rico by mogote. 2. Elongate hill or ridge capped by mogotes [10]. See mogote.
1716	percent saturation	The ratio, expressed as a percentage, of (a) the volume of some fluid (water, gas, or oil) to (b) the total volume of intergranular space (voids) in a given porous medium. Synonymous with degree of saturation [22].
1717	perched ground water	Ground water separated from an underlying body of ground water by an unsaturated zone [6]. See also ground water, perched.
1718	perched karst spring	See spring, perched karst.
1719	perched water table	Unconfined ground water separated from an underlying body of ground water by unsaturated soil or rock. It may be either temporary or permanent.
1720	percolate	To flow through saturated void space [16]. The act of water seeping or filtering through soil or rock without a definite channel [6].
1721	percolation; percolation water	1. Ground water moving slowly through the micro-fissure network of a limestone, most of which eventually joins a major cave conduit and flows more rapidly. In most environments percolation water enters the limestone through a soil cover. It is therefore high in carbon dioxide and has a major influence on limestone dissolution and later redeposition of calcite speleothems. Percolation water accounts for most of the storage in a limestone aquifer, responds slowly to flooding in comparison to sinkhole water, and is normally of high enough quality to provide a drinking-water supply [9]. 2. The movement in laminar flow under hydrostatic pressure of water through the interconnected, saturated interstices of rock or soil, excluding movement through large openings such as caves and solution channels. 3. The downward movement of water through the unsaturated zone [22]. 4. The downward flow of water in saturated or nearly saturated porous medium at hydraulic gradients of the order of 1.0 or less [22]. 5. The movement of water through saturated interior pore space [16]. Synonym: seepage water.
1722	percolation water	Autochthonous karst water which permeates directly through karst limestone without using a surface watercourse [19].
1723	perennial spring	See spring, perennial.
1724	perennial yield	Sustained yield [16].
1725	periodic spring	see spring, periodic.
1726	perforation	Holes or openings in well casing to permit water inflow into a well [16].
1727	permafrost	Ground that is perennially below the freezing point of water [16].
1728	permafrost karst	A nonkarst term. A pseudokarst developed in areas of permafrost due to melting of ice and frozen ground in a manner superficially similar to the solution of carbonate material in water. A general term embracing intrapermafrost karst, subpermafrost karst, and suprapermafrost karst [20]. (French) karst de permafrost; (German) Permafrost Karst ?, Pseudokarst; (Greek) karst monímou paghtoú; (Italian) pseudo-carsismo di permafrost; (Spanish) karst de permafrost; (Turkish) aldatıcı don karstı; (Yugoslavian) permafrost krs̃ (kras, karst).
1729	permafrost table	The upper limit of permafrost [16].
1730	permanent hardness	Noncarbonate hardness [16].
1731	permanent wilting point	Saturation at which permanent wilting occurs [16].
1732	permeability	See hydraulic conductivity; permeability, intrinsic .
1733	permeability barrier	See barrier, permeability.
1734	permeability coefficient	The rate of flow of water through a unit cross-sectional area under a unit hydraulic gradient at the prevailing temperature (field permeability coefficient) or adjusted to a temperature of 15°C [22].
1735	permeability, effective	The observed permeability of a porous medium to one fluid phase under conditions of physical interaction between this phase and other fluid phases present [22].
1736	permeability, intrinsic	1. A measure of the ability of a medium to transmit a fluid through a porous medium. It is a function of the medium only and is proportional to the mean grain size diameter. 2. A measure of the relative ease with which a porous medium can transmit a fluid under a potential gradient and is a property of the medium alone [22]. 3. The property of a porous medium itself that expresses the ease with which gases, liquids, or other substances can pass through it [22].
1737	permeability, relative	1. The ratio of the effective permeability for a given flow phase to the intrinsic permeability of the porous medium [22]. 2. The ratio of the effective and specific permeabilities [22]. 3. The ratio of permeability of one immiscible phase to intrinsic permeability in multiphase flow [16].
1738	permeability, specific	The permeability measured when the rock contains only one fluid [22].
1739	permeability tensor	Permeability in an anisotropic medium [16].
1740	permeability, transverse	Permeability measured perpendicular to the axis of a core sample [16].
1741	permeameter	A device used to measure the permeability of small samples [16].
1742	pervious	Permitting fluids to pass [16].
1743	petrography	The science of describing and identifying rocks [16].
1744	pH	A measure of the acidity or alkalinity of a solution, numerically equal to 7 for neutral solutions, increasing with increasing alkalinity and decreasing with increasing acidity. Originally stood for the words, potential of hydrogen [6].
1745	phonolite	A type of volcanic rock, common as lava flows in some areas, that is capable of supporting the formation of extensive lava caves, including those on Mount Suswa in Kenya [9].
1746	photogeology	The interpretation of aerial photographs for geological purposes [16].
1747	photogrammetry	The preparation of maps and measurements from stereoscopic aerial photographs [16].
1748	photosynthesis	The process by which green plants convert carbon dioxide and water into simple sugar. Chlorophyll and sunlight are essential to the series of complex chemical reactions involved in the process [23].
1749	phreas, phreatic water	(From the Greek word meaning well.) 1. The zone of saturated rock below the water table, within which all conduits and sub-conduits are water filled (sometimes referred to as the flooded, phreatic or saturated zone). Commonly the phreatic zone is considered as being subdivided into an upper (shallow phreatic) zone and a lower stagnant phreatic zone [9]. 2. Water in the zone of saturation; water below the water table [10]. See also bathyphreatic, bathyphreatic zone, ground water, phreas.
1750	phreas, dynamic	A phreatic zone or part of a phreatic zone where water moves fast with turbulence under hydrostatic pressure [25].
1751	phreatic cave	1. Cave conceived and developed by dissolution, usually below the water table, where all voids are water filled within the phreas. Phreatic caves may include loops deep below the water table, particularly in dipping limestone with widely spaced bedding-related fissures. Higher fissure densities, sub-horizontal geological guidance, or greater karstic maturity encourage shallow phreatic development just below the water table. Progressive abondonment of phreatic caves is usually in a downward sequence, as erosionally lowered valley floors intersect lower levels of the flooded system. Active phreatic cave segments, left perched for geological reasons after a general water-table lowering, are relatively common. Characteristics of phreatic caves are blind dissolution pockets on walls and ceilings, branching and looping of passages, and overall switchback gradients as phreatic flow may be uphill under pressure. The most common passage, and overall switchback gradients as phreatic flow may be uphill under pressure. The most common passage form is a tube, though cross-sectional shape reflects local geological factors. A classic active phreatic cave is that behind the Fontaine de Vaucluse in France, while Hölloch, Switzerland, is a major system consisting mostly of relict phreatic passages [9]. 2. Cave passage developed in the phreatic zone and still actively forming. Passages often appear as tubes.
1752	phreatic decline	The downward movement of the water table [16].
1753	phreatic fluctuation	The fluctuation of the water table [16].
1754	phreatic lift	An active or abandoned phreatic conduit that carries or carried water upwards in a downstream direction [9].
1755	phreatic line	See seepage line.
1756	phreatic rise	The upward movement of the water table [16].
1757	phreatic surface	See water table.
1758	phreatic water	That part of the underground water in a karst limestone which lies within the zone of permanently saturated rock — the phreatic zone. Caves formed within this zone are known as phreatic caves [19].
1759	phreatic zone	1. Those parts of the earth’s crust in which all voids are filled with water under pressure greater than atmospheric [22]. 2. That part of the earth’s crust beneath the regional water table in which all voids, large and small, are ideally filled with water under pressure greater than atmospheric [22]. When discussing a karst setting, it is preferable to use the term, phreatic zone, so as to avoid confusion regarding chemical saturation. Synonym: saturated zone. See also zone of saturation.
1760	phreatobia	An animal association found in water separating grains of sand or fine gravel [25].
1761	phreatobite	An inhabitant of groundwater, often exhibiting troglomorphy, but not limited to karst systems. Many examples of amphipods and other crustaceans abound [23].
1762	phreatophyte	Desert plants with deeply penetrating roots reaching the water table mainly along stream courses [16].
1763	physiography	The science of the origin and evolution of land forms [16].
1764	phytometer	A device used to measure the transpiration of plants embedded in soil [16].
1765	piedmont plain	A plain extending outwards from the base of a mountain system [16].
1766	piezometer	A devise used to measure ground-water pressure head at a point in the subsurface [22].
1767	piezometric head	The sum of the pressure and elevation head [16].
1768	piezometric limit	The point within a given flow path below which the flow direction is influenced by hydrostatic pressure. In cases where flow is confined to a planar structure, the piezometric limit can be identified as a point where the flow path changes from a dip-oriented to a strike- oriented trend. The piezometric limit is determined both by discharge rate and geometry of the openings. Used to describe karst aquifers with a discontinuous piezometric surface [14].
1769	piezometric surface	1. The imaginary surface to which water from a given aquifer will rise under its full static head [10]. 2. Defined by the elevation to which water will rise in artesian wells or wells penetrating confined aquifers [16]. See also potentiometric surface.
1770	pigment	A chemical substance that imparts color to an object by reflecting or transmitting only certain light rays and absorbing all others. For example, a substance that absorbs all but green rays appears green. An object that contains no pigment, on the other hand, appears white because it reflects all light rays and absorbs none. Many troglobites have lost all their pigment [23].
1771	pillar	1. Remnant of bedrock joining the cave floor and ceiling. Not to be confused with a column, which is a calcite deposit. Pillars are common in phreatic caves, formed by complexly looping ground-water flow, but may also be left as small oxbow cores of vadose origin. A spectacular group of pillars occurs in the ill-named Chamber of Columns in the Sof Omar cave, Ethiopia [9]. 2. A column of rock remaining after solution of the surrounding rock. 3. A stalactite-stalagmite that reaches from roof to floor in a cave; more properly termed a column. 4. A tall thin stalagmite that does not reach the roof of a cave [10]. See column; rock pillar.
1772	pinnacle karst	1. Tropical karst characterized by vertical rock blades fretted sharped by dissolution. It is practically indistinguishable from arête karst and tsingi, and includes the varieties known as shilin. The Pinnacles in the Mulu karst of Saraway have rock blades up to 50m high projecting through the rain forest canopy [9]. 2. A tropical landscape of bare reticulated saw-topped ridges having almost vertical slopes and a relief of as much as 120 meters. The ridges rise above forest-covered depressions and corridors. Found in New Guinea at elevations or around 2,000 meters [20]. Synonyms: (French) karst à pinacles; (German) Pinnacle Karst; (Greek) karst koriphón; (Italian) carsismo a pinnacoli; (Turkish) sivritepeli karst. Compare cone, cupola, tower karst.
1773	pinnacles	These are a particularly mature form of karren. The side walls are grikes with Rinnenkarren cutting across one another to form sharp edges and peaks that can reach several meters in height. Generally, pinnacles need a long period time to form. They are common in the tropics and can attain great sizes [3]. Often, they are covered. See also debris karren.
1774	pipe	1. A generally small, sub-cylindrical, vertical hole developed in an unconsolidated sedimentary deposit by the washing away of all or part of its fines content. Some pipes develop above points on a carbonate-rock surface, such as joint intersections, where ground-water seepage is locally concentrated. Pipes in chalk include cylindrical and conical masses of clay and sand that are neptunian fills of dissolutional dolines, shafts and caves; all shapes and sizes are commonly referred to as chalk pipes [9]. 2. Small cylindrical hole in unconsolidated sediments, caused by removal of fine material by water [10]. 3. A closed tubular conduit for fluid transport [16].
1775	piping	1. A process whereby a cavity or small conduit is developed in an unconsolidated soil due to progressive sediment removal by seepage water. The cavity develops headwards, as the fines are removed first and the coarser material is then washed out of the growing cavity [9]. Definition 1 is often incorrectly applied to the formation of sinkhole development — the migration of smaller particles through openings created by larger particles is of no consequence in terms of sinkhole development and should not be confused as such. 2. Formation of a passage by water under pressure in the form of conduits through permeable materials when the hydraulic head exceeds a certain critical value [10]. 3. The mechanical washout of caves in gravels, soils, loess, etc., and shows evidence of associated collapse.
1776	pisanite	A cave mineral — (Fe,Cu)SO₄·7H₂O [11].
1777	pisolite, pisolith	See cave pearl.
1778	pit	A deep hole, generally circular in outline, having vertical or nearly vertical walls [10]. See also jama; pothole (definition 2); shaft.
1779	pitch	Vertical or sub-vertical shaft or cave waterfall that normally requires rope, ladder or equipment to pass; a term used by British cave explorers [9].
1780	piton	1. (French) Limestone hill having sharply pointed peak [10]. 2. A solid or folded metal spike, of steel or other alloy, to be driven into a crack in the rock to form an anchor [25].
1781	pitot tube	A device used to measure flow velocity via pressure differences [16].
1782	pitted plain	Plain having numerous small closely spaced closed depressions [10].
1783	plan	A plot of the shape and details of a cave projected vertically onto a horizontal plane at a reduced scale [25].
1784	planarian	A flatworm. A relatively simple wormlike animal with a flattened ribbonlike body, a distinct head end, and a mouth located more or less centrally on the underside of the body [23].
1785	plane of weakness	Surface or narrow zone with a shear (or tensile) strength lower than that of the surrounding material.
1786	planimeter	An instrument that automatically determines irregular areas on a map [16].
1787	plateau	An elevated level land surface [16].
1788	Pleistocene	An epoch of the Quaternary period, after the Pliocene of the Tertiary and before the Holocene; also the corresponding worldwide series of rocks. It began two million years ago and lasted until the start of the Holocene some 8,000 years ago [1].
1789	plunge pool	A swirlhole, generally of large size, occurring at the foot of a waterfall or rapid, on the surface or underground [25]. See also swirlhole.
1790	pocket	Solution cavity in ceiling, floor, or walls of a cave, shaped like the interior of a round-bottomed kettle; unrelated to joints or bedding [10]. See also spongework.
1791	pocket valley	1. The reverse of a blind valley, extending headwards into the foot of a calcareous massif. The upstream end is terminated by a cliff, frequently lunate, from whose base emerges a subterranean karst stream meandering across a flat, steep-sided valley below the resurgence [19]. 2. A valley that begins abruptly and has no headwaters, having formed from and below the site of a spring [9].
1792	pocket storage	Water storage in depressions on the land surface [16].
1793	podzol	A light colored soil, usually found in forest regions [16].
1794	point-bar deposit	Sedimentation on the inside of a meander loop of a river or stream channel [16].
1795	point of inflection	The point where a curve changes slope [16].
1796	point source	Any discernable, confined, or discrete conveyance from which pollutants are or may be discharged, including, but not limited to, any pipe, ditch, channel, tunnel, conduit, well, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft [22].
1797	poise	A measure of viscosity.
1798	pokrytyĭ karst	(Russian) See covered karst.
1799	polarization	The migration and separation of ions to the electrodes in a direct current electrolyte process giving rise to higher overall resistance [16].
1800	polje	(Slavic word for field.) 1. A large, flat floored depression in karst limestone, whose long axis is developed parallel to major structural trends and can reach tens of kilometers in length. Superficial deposits tend to accumulate on the floor. Drainage may be by either surface watercourses (when the polje is said to be open) or swallow holes (a “closed” polje.) Their development is encouraged by any impedance in the karst drainage [19]. 2. Polje or karst polje signifies the flat-bottomed lands of closed basins which may extend over large areas, as much as 1,000 km2. The flat floor of the polje may consist of bare limestone, of a nonsoluble formation (and so with rolling topography), or of soil. The polje will show complex hydrogeological characteristics such as exsurgences, swallow holes, estavelles, and lost rivers. In colloquial use, the term polje is applied to flat-bottomed lands which are overgrown or are under cultivation [20]. 3. Large flat-floored closed karst depression, with sharp slope breaks between the commonly alluviated floor and the marginal limestone. Streams or springs drain into poljes and outflow is underground through ponors. Commonly the ponors cannot transmit flood flows, so many poljes turn into wet-season lakes. The form of some poljes is related to the geological structure, but others are purely the projects of lateral dissolution and planation. The Dinaric Karst has many poljes; the Livansko polje is around 60km long and 7km wide. The word is Slovene (common also to other Slav languages) for a field, reflecting the agricultural value of the alluvial polje floor soils [9]. Synonym: interior valley; (French) polje; (German) Polje; (Greek) polye; (Italian) polje; (Russian) polje; (Spanish) polje; (Turkish) gölova, polye; (Yugoslavian) polje. See also karst polje.
1801	pollutant or contaminant	Includes, but is not limited to, any element, substance, compound. or mixture including disease causing agents, which after release into the environment and upon exposure, ingestion, inhalation or assimilation into any organism, either directly from the environment or indirectly by ingesting through food chains, will or may reasonably be anticipated to cause death, disease, behavioral abnormalities, cancer, genetic mutation. Physiological malfunctions (including malfunctions in reproduction or physical deformation in such organisms or their offspring [22].
1802	polluted water	Water that has become contaminated by sewage or other contaminants such that the water quality has become severely degraded.
1803	pollution	1. Specific impairment of water quality by agricultural, domestic, or industrial wastes (including thermal and atomic wastes), to a degree that has an adverse effect upon any beneficial use of water [22]. 2. The addition to a stored body of water of any material which diminishes the optimal economic use of the water body by the population which it serves, and has an adverse effect on the surrounding environment [22].
1804	pollution abatement	All measures taken to prevent or to protect against pollution [16].
1805	polygonal karst	1. A karst area where the surface is completely pitted with closed depressions, the divides of which form a crudely polygonal network. Especially common in humid tropical cone-karst terrain, but also found in well-formed temperate doline-karst terrain [10]. 2. A type of karst in which numerous closed depressions are separated by dividing ridges that impose a crudely polygonal appearance upon the landscape [9].
1806	pond	A small body of surface water [16].
1807	ponded water	Water held in a depression by a barrier [16], such as breakdown in a cave system.
1808	ponor	(Slavic) 1. Hole or opening in the bottom or side of a depression where a surface stream or lake flows either partially or completely underground into the karst ground-water system. A sea- ponor is where sea-water flows or is drawn into an opening by a vacuum in karstified rock [20]. 2. Hole in the bottom or side of a closed depression through which water passes to or from an underground channel [10]. Synonyms: (British) swallet, swallow hole, stream sink; (French) ponor, aven, gouffre, perte; (German) Schlund, Saugloch, Schlinger, Ponor; (Greek) katavothra; (Italian) inghittitoio, capovento; (Russian) ponor; (Spanish) sumidero, ponor, pérdida; (Turkish) su yutan; (Yugoslavian) ponor, utok, požiralnik, pivka. See also swallow hole.
1809	ponornica	See lost river.
1810	pool deposit	Crystalline material deposited in an isolated pool in a cave [10].
1811	population	Individuals of a species in a given locality which potentially form a single interbreeding group separated by physical barriers from other such populations (e.g., populations of the same species in two quite separate caves) [25].
1812	pore	Small void space in rock or unconsolidated material of soil particles. See also interstice [16].
1813	pore deposit	Mineral matter deposited on the interior of a cave from water entering the cave so slowly through pores and cracks that it does not form drops [10].
1814	pore entry radius	The radius of a flow channel at pore entry, usually smaller than the average pore radius [16].
1815	pore pressure	The pressure of water in pores of a saturated medium [16].
1816	pore space	1. The total space not occupied by solid soil or rock particles [22]. 2. The space occupied by voids containing gases or liquids in soil or rock samples [16]. See also interstice; porosity; porosity, effective; porosity, primary; porosity, secondary.
1817	pore velocity	See velocity, average interstitial.
1818	porosimeter	A device used to measure porosity [16].
1819	porosity	1. The ratio of the aggregate volume of interstices in a rock or soil to its total volume; generally stated as a percentage [10]. 2. The ratio, usually expressed as a percentage, of the total volume of voids of a given porous medium to the total volume of the porous medium [22]. 3. The volume percentage of the total bulk not occupied by solid particles [22]. See also porosity, effective; porosity, primary; porosity, secondary; porosity, tertiary.
1820	porosity, absolute	Porosity established by taking into account all interconnected and nonconnected or isolated void volumes [16].
1821	porosity, effective	1. The ratio, usually expressed as a percentage of the total volume of voids available for fluid transmission to the total volume of the porous medium [22]. 2. The ratio of the volume of the voids of a soil or rock mass that can be drained by gravity to the total volume of the mass [22]. 3. The amount of interconnected pore space and fracture openings available for the transmission of fluids, expressed as the ratio of the volume of interconnected pores and openings to the volume of rock. See also porosity; porosity, primary; porosity, secondary; porosity, tertiary.
1822	porosity, primary	Porosity of some lithological material that developed while the rock was forming. See also interstice; pore; pore space; porosity; porosity, effective; porosity, secondary.
1823	porosity, secondary	Porosity of some lithologic material that has developed after the rock was initially formed, such as joints and fractures, and may be capable of enlargement by dissolution processes. See also pore; pore space; porosity, effective; porosity, primary; porosity, tertiary.
1824	porosity, tertiary	Porosity caused by solutional enlargement of secondary porosity. See also pore; pore space; porosity; porosity, effective; porosity, primary; porosity, secondary.
1825	porous	Having numerous interstices, whether connected or isolated.
1826	porous medium	Any medium containing interdispersed void space [16].
1827	porthole	A nearly circular natural opening in a thin rock wall in a cave [10]. See also window.
1828	potable water	Water that is suitable for human consumption [22].
1829	potamology	The study of streams.
1830	potential	Any of several different scalar quantities, each of which involves energy as a function of position or of condition; e.g., the fluid potential of ground water [22].
1831	potential density	1. The density of a unit of water after it is raised by an adiabatic process to the surface, i.e., determined from in-situ salinity and potential temperature [22]. 2. Density that would be reached by a compressible fluid if it were adiabatically compressed or expanded to a standard pressure [22].
1832	potential drop	The difference in total head between two equipotential lines [22].
1833	potential evapotranspiration	Evapotranspiration occurring under adequate soil-moisture supply at all times for given temperature and humidity conditions [16].
1834	potential flow	Irrotational flow occurring in a conservative force field or potential field [16].
1835	potentiometer	An instrument used to measure voltage differences [16].
1836	potentiometric field	As used in karst hydrology, a discontinuous highly irregular surface representing the static ground-water head as indicated by the level to which water rises in a selected piezometer. In some piezometers, the water-level rise will be greatly different from other piezometers (either higher or lower) or may be non-existent all together.
1837	potentiometric surface	An imaginary surface representing the total static head of ground water and defined by the level to which water will rise in a piezometer [22]. Replaces the term piezometric surface.
1838	pothole	1. A single shaft, or an entire cave system that is dominantly vertical. It is also used to describe a single erosional bowl or moulin, rounded mainly by the swirling current, in a stream bed [9]. 2. A small rounded hole pipe worn into the bedrock of a streambed, or on the coast, or at a waterfall, by sand, gravel, and stones spun around by the current in evorsion or mill action [20]. 3. Term used in England for vertical or steeply inclined shaft in limestone [10]. Synonyms: (French) marmite de géant, aven; (German) Kolk, Strudelloch; (Greek) strongíli opí is petróthi kítin révmatos; (Italian) marmitta dei giganti; (Russian) karstovaja sahta; (Spanish) marmita de gigante, pilancón; (Turkish) dev kazanı; (Yugoslavian) erozioni kotas. See also pit; shaft.
1839	potholer	(British) Explorer of openings in karst formations with emphasis on vertical and steep openings; somewhat of a slang term [20]. Synonyms: (French) spéléologue; (German) Speläologe, Höhlenforscher; (Greek) erevna karstikon engelon; (Italian) speleologo; (Spanish) espeleólogo, explorador de simas; (Turkish) dev kazancı; (Yugoslavian) speleolog, jamar. See speleologist, caver.
1840	potholing	1. The process of scouring holes in rock in stream beds or near the strand line by rapid rotation of trapped pebbles or cobbles; evorsion [10]. 2. (British) See caving.
1841	pozo	(Spanish) See sima.
1842	preadapted	Possessing adaptations that would contribute to survival in a habitat other than the immediate one because of similarities in living conditions in the two habitats. Insects that live in leaf litter on the forest floor, for example, may be pre-adapted to cave life [23].
1843	precipitation	1. Water precipitating in liquid or solid form from the atmosphere [16]. 2. The growth and development of crystals from solutions that are supersaturated with respect to various minerals.
1844	precipitation excess	That part of precipitation that contributes directly to runoff [16].
1845	precipitation gage	An instrument used to measure the amount of precipitation per unit area [16].
1846	predator	An animal that lives by capturing other animals for food [23]. See also prey.
1847	pressure	The force exerted across a real or imaginary surface divided by the area of that surface.
1848	pressure cell	A pressure measuring and transducing device [16].
1849	pressure cell	The pressure difference occurring between two points along a stream line in a flow system [16].
1850	pressure flow tube	Gallery with water flowing under pressure including differential gravity head and artesian pressure [20]. Synonyms: (French) galerie en conduite forcée; (German) Druckströmungsröhre, Karstgerinne; (Greek) ypoghion ytnatagogos, ypopiesin; (Italian) condotta forzata; (Russian) karstovij kanal s napornimi vodami; (Spanish) galería (o tubo) saturada; (Turkish) basınçlı su mecrası; (Yugoslavian) kanal s vodom pod tlakom. See also conduit; streamtube.
1851	pressure head	Hydrostatic pressure expressed as the height of a column of water that the pressure can support at the point of measurement [22]. See also head, static; pressure, hydrostatic.
1852	pressure, hydrostatic	The pressure exerted by the weight of water at any given point in a body of water at rest [22].
1853	prey	A living animal that is captured for food by another animal [23]. See also predator.
1854	prism storage	The storage of water in a river channel or reservoir in prism above the original water level [16].
1855	prismatic compass	A compass with a prism attached so that the compass card can be read at the same time as the compass is directed into the line of sight to a distance point [25].
1856	probe	A sensing instrument used to take measurements at the interior of a relatively unaccessible system [16].
1857	producers	Green plants, the basic link in any food chain; by means of photosynthesis, green plants manufacture the food on which all other living things ultimately depend. They are available in the cave community only in the twilight zone, or as debris that falls or washes in. A few types of bacteria also manufacture food from nonliving substances and therefore serve as producers in some cave communities [23]. See also consumer.
1858	projected section	The result of projecting a section composed of several parts with differing directions onto a single plane. Usually the plane is vertical along the general trend of the cave. The horizontal distance apart of points is not correct, only the vertical, so that slopes are distorted [25].
1859	proto-cave	Natural void that links a potential input point and an output point within an aquifer, but which is still too small to be entered by man [9].
1860	prusik knot	A knot tied by looping a smaller diameter rope around a larger standing line (rope) that has the property of sliding with no load on the knot, but will hold when it is loaded (e.g. when the weight of a caver is applied) [13]. See also ascender; mechanical ascender; prusiking; standing line.
1861	prusik sling	A sling fastened by a prusik knot to the rope [25].
1862	prusiking	The art of ascending a standing line (rope) by a caver with prusik knots [13] as opposed to the use of a mechanical ascender. See also ascender; knots; mechanical ascender; prusik knot; standing line.
1863	pseudokarren	These are karren appearing features that form mostly on insoluble, silicate rocks by means of weathering processes. They appear as a rounded type of Rinnenkarren and less frequently as an atypical form of solution pan [3]. See also karren; Rinnenkarren; solution pan.
1864	pseudokarst	1. Terrane with features similar to karst but formed in nonsoluble rocks, as by melting of permafrost or ground ice, collapse after mining, and by outflow of liquid lava from beneath its solidified crust [20]. 2. Karst-like terrane produced by a process other than the dissolving of rock, such as the rough surface above a lava field, where the ceilings of lava tubes have collapsed. Features of pseudokarst include lava tunnels, lava tubes, lava stalactites, and lava stalagmites [10]. 3. A landscape containing karst-like features such as caves and dolines, but not formed by bedrock dissolution as in true karst. Pseudokarst embraces volcanic landscapes with lava caves, cryokarst or thermokarst formed by ground-ice melting in a permafrost environment, and situations where mechanical soil piping has occurred, producing depressions and pipes, as occur commonly in areas of loess cover [9]. Synonyms: (French) pseudokarst; (German) Pseudokarst; (Greek) psevthokarst; (Italian) pseudocarsismo; (Russian) psevdokarst; (Spanish) pseudokarst; (Turkish) aldatıcı karst; (Yugoslavian) pseudoks̃, pseudokras, pseudokarst, navidezni kras. See lava cave, lava karst, pahoehoe.
1865	pseudo-breccia	A type of limestone resembling a breccia, in which angular limestone fragments are cemented together by limestones of different composition. Pseudo-breccias are common in many preserved limestone sequences and may owe their origin to the dissolutional removal of originally interbedded and interstitial sulfate minerals followed by break-up and redistribution of the residual carbonate component [9].
1866	psychrometer	1. An instrument used for measuring relative humidity. The simplest sling psychrometers consist of two thermometers mounted on a rotating frame. One thermometer’s bulb is kept moist, the other dry. By comparing the “wet bulb” and “dry bulb” readings of the two thermometers after they have been whirled in the air, one can determine the relative humidity. An electric fan is used to ventilate the wet bulb in many psychrometers [23]. 2. Apparatus designed to measure relative humidity indirectly [16]. See also hygrometer.
1867	puddle	Water collecting in very small surface depressions [16].
1868	pumping test	A test designed to determine aquifer characteristics by pumping a well and plotting the drawdown curves of observation wells for comparison with theoretical curves.
1869	pupa (plural pupae)	The inactive stage in the life history of certain insects during which the larva undergoes a gradual reorganization of its tissues in the process of becoming an adult. See also metamorphosis.
1870	pycnometer	A bottle with an accurately determined volume for density determinations [16].
1871	pyrite	Iron sulfide mineral (FeS₂) also known as iron pyrites and fool’s gold. Pyrite occurs in trace amounts in many sedimentary rocks. It may be locally common in dark carbonaceous limestone and in thin non-carbonate beds such as shales, coals and wayboards. Pyrite may break down spontaneously, with or without bacterial mediation, to form sulfates, particularly sulphuric acid, that may be involved in early speleogensis [9].
1872	pyrrhotite	A cave mineral — FeS [11].
1873	quagmire	A wet unstable land area [16].
1874	quartz	A crystal form of silicon dioxide (SiO₂) [16].
1875	quiet reach	The reach of a river with no features disturbing the flow pattern [16].
1876	rabies	An infectious disease of the central nervous system in mammals, caused by a lyssavirus. Usually transferred by the bite of an infected animal, such as dogs, skunks, racoons, or rarely bats. Characterized by choking, convulsions, inability to swallow, etc. Different genetic strains are now recognized and can be identified by tests. Transfer of rabies from bats via aerosols to caged animals in a cave has been demonstrated, but has not been proven in humans [23].
1877	radial flow	1. Radial flow into or out of a well under ideal circular boundary conditions [16]. 2. The flow of ground water in all directions in response to recharge entering the subsurface at or near the top of a ground-water plateau. This conditions occurs most often through point recharge entering the subsurface via sinkholes in karst terranes.
1878	radioactive tracer	A tracer used in hydrological direction and velocity determinations [16]. The two most common types are tritium and deuterium.
1879	radioactivity log	A log measuring radioactivity in a borehole [16].
1880	radioisotope	An unstable isotope of an element that decays or disintegrates spontaneously, emitting radiation [22].
1881	radionuclide	A radioisotope [22].
1882	radionuclide retardation	The process or processes that cause the time required for a given-radionuclide to move between two locations to be greater than the ground-water travel time, because of physical and chemical interactions between the radionuclide and the geohydrologic unit through which the radionuclide travels [22].
1883	radius of influence	The radial distance from the center of a well bore to the point where there is no lowering of the water table or potentiometric surface (the edge of its cone of depression) [6].
1884	raft	A thin sheet of crystalline calcite supported by surface tension on a cave pool or lake. The calcite is precipitated mainly in response to evaporation of the pool water and rafts are therefore found mainly in caves in arid regions or caves with powerful through draughts.
1885	rain	Liquid precipitation of atmospheric water in the form of droplets [16].
1886	rainfall excess	That portion of rain fall that contributes directly to runoff [16].
1887	rainfall intensity	The volume or depth of rainfall per unit time [16].
1888	rain gage	An instrument used to measure the height of rainfall [16].
1889	rain gage network	An areal distribution of rain gages [16].
1890	rain intensity	The intensity of rain fall expressed in depth per time (in/hr) [16].
1891	randpolje	An enclosed plain at the edge of a karst area receiving surface water from the nonkarstic area. The water drains out through underground passages in the karst area. The plain is thus completely enclosed by higher ground. Compare blind valley; karst margin plain [10].
1892	rappel	The art of descending a rope using some sort of friction between the rope and the rappeller to control the rate of descent [13]. Synonym: abseil. See also abseil; carabiner.
1893	rappel rack	A long U-shaped steel bar that holds several brake bars and is used for rappelling [13]. See also rappel.
1894	rappel spool	One of the devices used to create friction between a rappeller and the rope that consists of a spool on which the rope can be wrapped around several times [13]. See also rappel.
1895	rapid	A stream section with a notably higher flow velocity than in adjoining parts [16].
1896	rapid flow	Open channel flow with a Froude number greater than unity [16]. See also Froude Number.
1897	rate of draft	The rate at which water is required for use (demand) [16].
1898	rate of infiltration	The maximum rate at which soil can absorb water [16].
1899	rating curve	The graphic relationship of stage to discharge [16].
1900	rational formula	An equation relating runoff intensity and area to a runoff coefficient [16].
1901	ravine	A small erosional depression [16]. See chasm.
1902	raw sewage	Untreated sewage.
1903	raw water	Untreated water [16].
1904	reaction path modeling	A simulation approach to studying the chemical evolution of a (natural) system [22].
1905	rebelay	The reanchoring of a rope, usually to avoid rub points or split long pitches.
1906	Redirection	Syn. deviation
1907	rebound	An upward movement of soil as a consequence of a decrease in effective stress. In fine- grained soils, rebound is usually much less than the amount of compaction since compaction is mostly irreversible [21].
1908	receiver	That part of a remote measuring system that receives incoming data or impulses [16].
1909	receiving surface	A surface receiving precipitation or radiation [16].
1910	recessional moraine	A moraine deposited by a retreating glacier [16].
1911	recession curve	The falling limb of a hydrograph curve [16].
1912	recession flow	The flow that occurs after rainfall has ended [16].
1913	recession segment	That part of a hydrograph that represents the withdrawal of water from storage [16].
1914	recharge	1. The process of addition of water to the saturated zone [22]. 2. The artificial replenishment of a depleted aquifer by injection or infiltration of water from the surface [16].
1915	recharge, allogenic	Recharge derived from runoff of neighboring or overlying non-karst rocks that drains into a karst aquifer. Diffuse allogenic recharge is used to describe the slow percolation of recharge when runoff into direct input points is reduced in magnitude while concentrated allogenic recharge is used to describe the concentrated recharge that occurs by runoff into large fractures, sinkholes, and sinking streams.
1916	recharge area	An area in which water reaches the zone of saturation by surface infiltration [22]. See also intake area.
1917	recharge, autogenic	Recharge derived from precipitation directly onto the karst landscape. Diffuse autogenic recharge is used to describe the slow percolation of recharge through a myriad of small openings while concentrated autogenic recharge is used to describe the concentrated recharge that occurs by flow into large fractures, sinkholes, and sinking streams.
1918	recharge capacity	The ability of the soils and underlying materials to allow precipitation and runoff to infiltrate and reach the phreatic zone [22].
1919	recharge line	A series of recharge wells arranged in linear fashion to approximate a line source [16].
1920	recharge pit	A large diameter well or shaft for recharge under gravity [16].
1921	recharge water	Water used for replenishment of a depleted aquifer [16].
1922	recharge well, absorbing well, diffusion well, inverted well	A well that is used to recharge water back into an aquifer. Commonly used when aquifer depletion, saltwater intrusion, and contaminant migration are problems.
1923	recipient	A vessel receiving liquids in volume measurements [16].
1924	reclamation	To reclaim land after abusive effects such as strip mining.
1925	recorder	An instrument designed to continuously or intermittently record measurements [16].
1926	recovery	The water-level rise in a well occurring upon the cessation of discharge from that well or an observation well.
1927	recovery method	A pumping test analysis method in which both drawdown and recovery of head after cessation of pumping are observed and plotted for the same observation well [16].
1928	recrystallization	A new formation of crystals from solid rock material [16].
1929	reculée	See pocket valley.
1930	redirection	See deviation.
1931	redox	A chemical reaction in which an atom or molecule loses electrons to another atom or molecule. Also known as oxidation-reduction. Oxidation is the loss of electrons; reduction is the gain of electrons [6].
1932	redox potential (Eh.)	Oxidation-reduction potential [16].
1933	reef	A dissected ridge of rocks totally or partially submerged in sea water; often of organic origin [16].
1934	regelation	The melting of ice under pressure and subsequent freezing [16].
1935	rigging	The process of establishing the belays for SRT or laddering [25]. See also single rope technique.
1936	region of dispersed water	The diffuse interface between freshwater and sea water caused by mixing in a coastal aquifer [16]. See also transition zone.
1937	regolith	A general term for the layer of fragmental and unconsolidated rock material that nearly everywhere forms the surface of the land and overlies or covers the bedrock [6].
1938	regosol	Dry sandy soil [16].
1939	regression line	A curve fitted to all mean values of one variable [16].
1940	rejuvenation	A process that interrupts an active erosional or development cycle and initiates a new cycle. Rejuvenation is most commonly achieved in the karst and speleogenesis context by erosional base-level changes caused by relative uplift (or sea-level fall) or by local water-table changes caused by downcutting of surface valleys intercepting deeper drainage lines [9].
1941	relapsing fever	One type of Borreliosis, caused by various species of Borrelia spirochaetes carried by several species of tick. Related to Lyme disease, but less chronic and milder. An occupational disease of some cavers in Texas who come in contact with the soft tick Ornithodoros turicatae, which carries Borrelia turicatae and may live in cave entrances [23].
1942	relative humidity of atmosphere	The ratio of absolute humidity to the maximum possible saturation at given conditions [16].
1943	relative permeability	See permeability, relative.
1944	relict cave	Abandoned, inactive cave segment, left when the water that formed it is diverted elsewhere, normally due to rejuvenation, continuing cave development and increasing karstic maturity. Relict unmodified phreatic passage segments are abandoned in the vadose zone, where they may remain dry, retaining a typical phreatic morphology, or be invaded and modified to a keyhole profile by new streams. Ages of relict caves vary greatly and due to lack of stream-flow breakdown and speleothem deposition may become the dominant processes. Relict caves are commonly referred to incorrectly as fossil caves [9].
1945	relict karst	A karst area that exists within the contemporary system, but has been removed from the situation in which they developed, usually as a result of base-level changes.
1946	relief	Elevation differences in topography of a land surface [16].
1947	relief intensity	The average altitude difference between the highest point of a basin and the valley bottom [16].
1948	replenishment	The restoration of water in a depleted aquifer [16].
1949	resequent river	A river flowing according to a consequent drainage pattern but at a lower level than the original slope [16].
1950	reservoir	1. A recipient for the collection of small amounts of liquid [16]. 2. A surface water impoundment [16].
1951	reservoir evaporation	Evaporation from the free surface of impounded water bodies [16].
1952	reservoir lake	A lake obtained by the impoundment of water for storage purposes [16].
1953	residual clay	Clay or sandy clay remaining on a rock surface after removal of calcium carbonate by solution. Compare terra rossa [10].
1954	residual drawdown	The rise in water level in a well in response to cessation of pumping.
1955	residual hill	See emergence.
1956	residue	Solids remaining after evaporation [16].
1957	resurgence	1. Re-emergence of karst ground water a part or all of whose waters are derived from surface inflow into ponors at higher levels [20]. Point at which an underground stream reaches the surface and becomes a surface stream. In European literature, the term is reserved for the re- emergence of a stream that has earlier sunk upstream; the term exsurgence is applied to a stream without known surface headwaters [10]. Synonyms: (French) résurgence; (German) Karstquelle; (Greek) kephalari; (Italian) risorgenza; (Russian) vihod karstovih vod; (Spanish) resurgencia; (Turkish) suçıkan; (Yugoslavian) krs̃ki izvor (vrelo), obrh. See emergence. Compare exsurgence.
1958	retardation factor	The ratio of the average linear velocity of ground water to the velocity of the retarded constituent at C/C_o = 0.5 [22].
1959	retention	1. The detention of water on surface depressions or in subsurface void space. 2. the retention of water in pores against gravity [16].
1960	reverse fault	A fault where relative movement of the hanging wall has occurred in the upward direction [16].
1961	Reynolds number	A numerical quantity used as an index to characterize the type of flow in a hydraulic structure in which resistance to motion depends on the viscosity of the liquid in conjunction with the resisting force of inertia. It is the ratio of inertia forces to viscous forces, and is equal to the product of a characteristic velocity of the system (e.g. the mean, surface, or maximum velocity) and a characteristic linear dimension, such as diameter or depth, divided by the kinematic viscosity of the liquid; all expressed in consistent units in order that the combinations will be dimensionless. The number is chiefly applicable to closed systems of flow, such as pipes or conduits where there is a free water surface, or to bodies fully immersed in the fluid so the free surface need not be considered [1]. See also Chézy equation; Froude number; Manning equation.
1962	rhodamine dye, sulpho rhodamine dye	Orange dyes used in environmental tracing studies that fluoresce red when held under a black light. See also fluorescent dyes.
1963	rice paddy	In a cave, a terraced rimstone pool [10].
1964	ridge	An elongated narrow elevation [16].
1965	rift	1. A cave passage that is relatively high and narrow. Generally rifts are straight or nearly so, reflecting that they are commonly guided by, and developed along, vertical or sub-vertical fissures, joints and faults [9]. 2. A long narrow high cave passage controlled by joints or faults [10].
1966	rift valley	A surface depression due to the formation of graben block faulting [16].
1967	rill	1. Small solution groove on surface exposures of limestone; most common in arid or semiarid areas [10]. 2. Small channel cut by flowing water in the floor, wall, or ceiling of a cave [20]. 3. The smallest category of stream in any terrane [20]. Synonyms: (French) traces de ruissellement; (German) Rinne, Kerbe; (Greek) riákion; (Italian) solchi di ruscellamento; (Spanish) arroyuelo; (Turkish) küçük dere, oluk, ark.
1968	Rillenkarren	(German) Solution flutes that occur only in places where fresh unspent precipitation is active and end where the water attains too high a content of lime or where water is added. Their length increases with slope, temperature, and rainfall; eventually reaching 1 m and more in the tropics, up to 50 cm, and as an exception, 100 cm in the Alps. Their width extends from 1 to 3 cm. They lie together in rows with no space between, with sharp intermediary ridges of no more than 1 cm in height. They increase at all freely exposed peaks and ridges where fresh rainwater alone is at work. The grooves gradually flatten out to a smooth surface. Their theory of origin is unknown. [3]. Synonyms: (German) Kannelierungen; solution flutes; and firstkarren.
1969	Rillenstein	(German) Microsolution grooves and pitting on rock surface [10].
1970	rimstone	1. A wall-shaped deposit around springs and below cascades which impounds water in pools. Its formation is due to precipitation from saturated bicarbonate waters [20]. 2. Calcareous deposits formed around the rims of overflowing basins, especially in caves [10]. Synonyms: (French) gour; (German) Sinterbecken; (Greek) frágma, epiphliomatos; (Italian) vasche d’incrostazione; (Russian) natecnaja plotina; (Spanish) dique travertínico; (Turkish) sedde, kenartaşı. See constructive waterfall, rimstone barrage, rimstone pool.
1971	rimstone barrage, rimstone barrier, rimstone dam	A wall-shaped deposit that impounds pools of water in caves, around springs, and in cascades of streams saturated with calcium bicarbonate [10]. Synonym: (French) gour. See also rimstone; rimstone pool.
1972	rimstone pool	A pool sited on a cavern floor and enclosed by a rim of carbonate reprecipitated from the karst water in the pool at points locally favoring the release of carbon dioxide [19]. See also rimstone; rimstone barrage.
1973	Rinnenkarren	(German) Solution grooves that form where runoff water is collected in streams. If the whole surface is moistened, the amount of water increases downwards with the result that the grooves are widened and deepened at the bottom. This distinguishes them from other similar forms. When the slope is slight they are coiled, but become straighter with increasing inclination. They are sometimes interpreted to be subcutaneous forms that develop below soil cover, but this is believed to be a rare occurrence. They are found in all climates. In arid zones, they exist as relics of the past when the climate was damper [3].
1974	ripple mark	A wavelike sculpture on water covered sand surfaces obtained by wave action [16].
1975	rise	(Jamaican) Spring rising from fractures in limestone. Point at which an underground stream comes to the surface [10].
1976	rise pit	An artesian spring rising up through alluvium accumulated in an earlier surface valley phase and often fringed, except on the outlet side, by a minor levee deposited as the force of the vertical discharge dissipates at the surface [19].
1977	riser	A pipe through which liquid rises in a well [16].
1978	riser pipe	A pipe through which water is raised in a production well [16].
1979	rising	1. The resurgence of an underground watercourse, usually at the base margin of the calcareous massif, although in the instance of a blind valley the rising has eroded headwards for some distance. Each rising accounts for the collective discharge of several sinks and in this way has a relatively high discharge as the sole drainage outlet for a large area. If the water issues freely, the rising is said to be free-flowing, but if it issues under pressure, the terms artesian, forced, or vauclusian spring are used (after the type-example of the resurgence of the Sorgue river at Vaucluse in France) [19]. 2. An issue of water from massive limestone which cannot be classed with certainty as either a resurgence or a spring [20]. Synonyms: (French) émergence; (German) Ausflußtelle, Karstquelle; (Greek) kephalari; (Italian) sorgente; (Russian) vihod karstovih vod; (Spanish) emergencia; (Turkish) yüzeye yükseliş; (Yugoslavian) krs ̃ko vrelo, krs ̃ki izvor, obrh. See also emergence; exsurgence; resurgence.
1980	rising segment	That part of a hydrograph curve that represents a rise in water level as a result of precipitation [16].
1981	river	A natural water course through which runoff reaches the sea [16].
1982	river bed	The channel of a river covered by water [16].
1983	river reach	A particular segment of a river [16].
1984	river swamp	A swamp in lowlands adjoining a river [16].
1985	river system	The system of a main river that includes all its branches and tributaries [16].
1986	river terrace	A level land terrace formed in a valley by fluviatile erosion or aggradation [16].
1987	rivulet	A very small stream [16].
1988	rock	Consolidated mineral matter of igneous, sedimentary, or metamorphic origin [16].
1989	rock fall	See cave breakdown.
1990	rock formation	A lithologically or structurally distinct part of the lithosphere [16].
1991	rock-hill	See karren, rill.
1992	rock milk	Less common synonym for moonmilk [9]. See moonmilk.
1993	rock pendant	See pendant.
1994	rock pillar	A residual isolated mass of bedrock linking the roof or overhanging wall and floor of a cave, in contrast with a column, which to composed of dripstone or flowstone [10]. See column; pillar.
1995	rock pinnacle	A tall sharp projection of bedrock rising from the floor of a cave [10].
1996	rock shelter	1. Shallow cave under an overhanging rock ledge. Many sea caves are rock shelters. Also found in limestone and other rock types where streams have undercut their banks at bends, or where there has been abrasion by blowing sand. Common in tropical areas at places where a secondarily hardened layer of limestone forms a ledge that projects over unindurated limestone [10]. 2. A wide but shallow cavity in any rock; in carbonate rock often formed below a noncarbonate layer [20]. Synonyms: (French) abri sous roche, balme, baume; (German) Halbhöhle, weite aber flache Höhle; (Greek) kataphyion; (Italian) riparo sotto roccia, androne; (Spanish) abrigo, balma; (Turkish) kaya siginagi; (Yugoslavian) potkapina, okapina, polupećina, spodmol, zijalka.
1997	rock system	Rocks deposited during a given geological time period [16].
1998	rock terrace	A terrace formed by erosional action and denudation [16].
1999	rock texture	The geometrical aspects and arrangement of the component particles of a rock [16].
2000	rockhole	A shallow, small hole in rock outcrops, often rounded in form and holding water after rains. Well known on the Nullarbor Plain, Australia [25].
2001	rockpile	A heap of blocks in a cave, roughly conical or part-conical in shape [25].
2002	rockfall	The falling of bedrock from a cliff or steep slope [16].
2003	romanechite	A cave mineral — BaMn₉O₁₆(OH)₄ [11].
2004	roof crust	Flowstone deposited on ceilings of caves from thin films of water, which have crept over the rock from pore or crack sources [10].
2005	roof drainage	Precipitation runoff from roofs.
2006	roof pocket	Blind upward extension into the ceiling of a cave passage, commonly enlarged by dissolution along a transverse fracture, and less extensive than an aven or chimney [9].
2007	roof slab	See ceiling slab.
2008	room	A part of a cave system that is wider than a passage [10]. Synonym: (British) chamber.
2009	root karren	These are small, relatively flat karren that are formed beneath compact soils where roots etch into the limestone [3]. See also covered karren; wave karren.
2010	root zone	The zone in a soil profile penetrated by plant roots [16].
2011	rope protector	A length of heavy fabric or plastic hose placed around a rope where it may rub against rock [25].
2012	rotating meter	A stream velocity meter that transforms stream momentum into angular momentum by vanes and rotor [16].
2013	roughness	An unevenness of surfaces giving rise to high flow resistances [16].
2014	roughness coefficient	A coefficient that describes roughness of a channel bed [16].
2015	round karren	See Rundkarren.
2016	roundness	The degree to which a sand grain approaches spherical shape [16].
2017	rout, to	The action of predicting and directing of flood waves through a channel system [16].
2018	run dry, to	The cessation of flow from a well or spring [16].
2019	Rundkarren	(German) 1. Karren forms with rounded edges; formed by soil water than cannot flow freely due to the tightness of soil pores and thus corrodes away all edges and points. The small karren forms disappear, grooves and grikes are widened and deepened. One or two centuries after being laid bare, the earlier rounded edge is only just recognizable so round karren and their remains provide evidence of an earlier soil covering [3]. 2. Karren form comprising rounded channels, commonly 50–500mm deep and wide and separated by rounded ridges. Rundkarren are the characteristic dissolutional form created beneath superficial material such as sandy till, peat or other soil, or beneath a cover of plants or lichen [9]. Synonym: round karren. See also Karren.
2020	runoff	1. The discharge of water through the surface streams of a drainage basin [16]. 2. The sum of surface runoff and ground-water flow that reaches a stream [16].
2021	runoff coefficient	A dimensionless coefficient to estimate runoff as a certain percentage of storm rainfall [16].
2022	rupture	That stage in the development of a fracture where instability occurs. It is not recommended that the term rupture be used in rock mechanics as a synonym for fracture.
2023	sabath	See hardpan, nari.
2024	safe yield	The amount of water that can be safely withdrawn from an aquifer without causing undue effects such as aquifer depletion.
2025	safe yield of stream	The lowest dry weather flow of a stream [16].
2026	safety line	A safety rope attached to a caver climbing on a ladder or negotiating a difficult situation and held by a man above [25].
2027	saline spring	See spring, saline.
2028	saline water	Water that generally is considered unsuitable for human consumption or for irrigation because of its high content of dissolved solids. Generally expressed as milligrams per liter (mg/L) of dissolved solids, with 35,000 mg/L defined as sea water, slightly saline is 1,000-3,000 mg/L, moderately saline is 3,000-10,000 mg/L, very saline is 10,000-35,000 mg/L, and brine has more than 35,000 mg/L [22].
2029	salinity stratification	The stratification of water in estuaries due to salinity-density differences [16].
2030	salt dome	A dome-like intrusion of a mobile salt core into sedimentary rock [16].
2031	salt karst	Areas in which karst landforms are developed upon halite or halite-rich rock, which are generally small and limited to arid regions, are referred to as salt karst. Except in desert regions, dissolution of rock salt occurs in buried, interstratal, situations, and the effects of such dissolution at the surface include subsidence pipes or wider subsidence areas, such as those represented by the meres and “flashes” in the Cheshire Plain, England [9].
2032	salt lake	A lake containing high salt concentrations and usually not having any outflow [16].
2033	salt tolerance	The resistance of crops to salt concentration [16].
2034	salt weathering	Detachment of particles of various sizes from a rock surface by the growth of crystals from salt solutions. Forms substantial features in Nullarbor Plain caves [25].
2035	saltation	Solid matter transported by a stream by the action of leaping movement over the stream bed. See also saltation load.
2036	saltation load	The solid matter transported by streams [16].
2037	saltwater intrusion	The movement of salt water into fresh water aquifers [22].
2038	sampling	The taking of small quantities of water or porous media for analysis [16].
2039	sand	Unconsolidated detrital rock material [16].
2040	sand pipe	See solution pipe.
2041	sand stalagmite	A stalagmite formed on sand and made of calcite-cemented sandstone [10].
2042	sandstone caves	Most natural sandstone caves are surface river-cut notches at the foot of rock cliffs, or left part way up the cliff due to later downcutting. This origin accounts for most of the caves once inhabited by the Pueblo Indians in the sandstone cliffs of the western USA. True caves do occur in sandstone and some of these appear to be at least partially of dissolutional origin. Their existence probably reflects matrix leaching by ground water moving through zones of especially high primary porosity and permeability. Though sandstones with a calcite matrix cement are more prone to such development, even siliceous cement, which has a very low solubility in water, may be removed during a sufficiently long time span. The sandstone caves of the Sarisarinama Plateau, Venezuela may be a special case of this type of development. These include shafts 300m in diameter and 200m deep, and passages up to 500m long. They were probably cut in the quartz sandstone by underground streams, after early leaching of the cement by hydrothermal solutions, and the shafts have been modified by later collapse [9].
2043	saprophage	A scavenger feeding on decaying organic material [25].
2044	saturated	1. Referring to rock with water-filled voids. 2. Referring to water which has dissolved as much limestone or other karst rock as it can under normal conditions [25].
2045	saturated flow	Single phase flow when all voids are filled [16]. Not to be confused with chemical saturation.
2046	saturated water	Water which is in chemical equilibrium with its enclosing media and is thus nonagressive. Water, at about 25○C, in contact with calcite and the normal atmosphere, will contain approximately 30 to 50 ppm of Ca when saturated, variations being mainly due to differing pH. Determination of the saturation point of natural waters is complex [20]. Synonyms: (French) eau saturée; (German) gesättigtes Waßer; (Greek) koresménon ýdor; (Italian) acqua satura; (Spanish) agua saturada; (Turkish) doygun su; (Yugoslavian) zasićena voda.
2047	saturated zone	See phreatic zone and zone of saturation.
2048	saturation regime	A flow regime in completely saturated porous medium [16].
2049	saturation, zone of	See phreatic zone and zone of saturation.
2050	scale	1. A very thin and flat rock fragment [16]. 2. The accumulation of precipitated solid material. 3. The ratio of prototype to model dimensions. 4. The ratio of the length between any two points on a map, plan or section to the actual distance between the same points on the ground or in a cave [25].
2051	scaling chip	A thin small rather irregular piece of limestone, commonly crumbly, which has fallen from the ceiling or wall of a cave. A form of cave breakdown [10].
2052	scaling factor	The ratio of characteristics of a model to those of the prototype [16].
2053	scaling plate	A small flat piece of rock of rectangular or polygonal shape, that has fallen to the floor of a cave. A form of cave breakdown in thin-bedded impure limestone cut by closely spaced joints [10].
2054	scaling poles	A lightweight metal alloy pole, in short sections for transport and fastened together where used, to raise a ladder to points inaccessible by climbing [25].
2055	scallop	1. A spoon-shaped hollow carved in a cave wall, floor or ceiling due to erosion by eddies in flowing water. Scallops are commonly closely packed, leaving sharp ridges at the intersects. They range from 10mm to 1m in length and as a general rule the smaller they are then the faster flowing was the water that carved them. The scallops are generally asymmetrical, with their upstream end steeper than the downstream end — a useful indicator of paleo-flow direction in abandoned passages [9]. 2. Oval hollow having an asymmetric cross section along its main axis. Scallops form patterns on the walls of caves and in streambeds and may be used to determine direction of flow of turbulent water, since they are steeper on the upstream side. Commonly called flutes in America [10]. Synonyms: (French) cannelure, vague d’érosion; (German) in Fließrichtung des Waßers ausgezogener Kolk; (Greek) kílon o-oïthés; (Spanish) huella de corriente; (Turkish) degirmi, tarak. See also flute.
2056	scar	(Northern England.) Steep rock cliff in limestone country often indicating outcrop of relatively bare and massively bedded limestone [20]. Synonyms: (French) cicatrice, griffure; (German) Klippe; (Greek) oulí; (Spanish) ceja (in central Spain); (Turkish) kireçtaşı dik yarı.
2057	scats	Animal droppings, an important source of food in caves [23].
2058	scavenger	An animal that eats the dead remains and wastes of other animals and plants [23]. See also predator.
2059	Schichtfugenkarren	(German) See bedding grike.
2060	scholzite	A cave mineral — CaZn₂(PO₄)₂·2H₂O [11].
2061	scour	The erosive action of running water in streams [16].
2062	screen, screen pipe	Slotted well casing that is positioned within the producing horizon to prevent the inflow of detrital particles into a well while allowing the inflow of water. See also well screen.
2063	sea cave	1. A cave cut in any rock type where a geological weakness is exploited by the highly selective erosion power of wave action. Fingal’s Cave, cut in the basalt of Staffa, Scotland, is a famous example. True sea caves should not be confused with dissolutional caves that pre-dated the wave action but were then intersected and revealed as a cliff line was eroded back such as caves in the Chalk at Beachy Head in south-east England. In some young tropical islands, dissolutional voids have formed below sea-level in the mixing zone between fresh and saline ground water. Some have subsequently been tectonically uplifted into a shoreline position, to give the misleading impression of having developed due to waver action. Caves of this type on the coast of Tongatapu, Tonga, have pools that connect with active dissolutional cavities below sea-level that might be related to the mixing zone [9]. 2. A cave or cleft in a sea cliff or coastal karst outcrop eroded by waves or currents or dissolved by circulating ground water [20]. Synonyms: (French) grotte marine; (German) Küstenhöhle, Meereshöhle; (Greek) thalassion spelson - paraktion speleon; (Italian) grotta marina; (Russian) morskaja pescera; (Spanish) cueva marina; (Turkish) deniz mağarası; (Yugoslavian) morska pećina (spilja). See cave. Compare nip. See also littoral zone.
2064	sea estavelle	Submarine or sea-shore opening in karst formations which at one season or period discharges round water (fresh or brackish) from the aquifer into the sea-bed and at another season or period draws seawater into the aquifer by a vacuum [20]. Synonyms: (French) estavelle marine; (German) submarine Estavelle; (Greek) estavelle thalassia (estavella); (Italian) Estavella sottomarina, sorgente sottomarina a flusso alterno; (Spanish) estavela marina; (Turkish) sahil batar çıkarı.
2065	sea level	The average height of the surface of the sea used as a datum for elevations [16].
2066	sea-mill	A mill whose motive power is derived from the flow of water into (or possibly out of) a sea estavelle; the classical example is on the Vinaria Peninsulas, at Argostolion, Kephallinia [20]. Synonyms: (French) moulin de la mer, moulin d’Argostoli; (German) Meermühle; (Greek) thalassomylos; (Spanish) molino de mar; (Turkish) deniz suyu degirmeni; (Yugoslavian) morska vodenica. See sea estavelle.
2067	sea ponor	A submarine opening in karst formations where seawater flows or is drawn by a vacuum into the aquifer [20]. Synonyms: (French) perte sous-marine; (German) submariner Ponor; (Greek) ypothalassia katavothra; (Italian) inghiottitoio sottomarino; (Spanish) sumidero marino; (Turkish) denizalte suyutanı; (Yugoslavian) morska vodenica, morski ponor. See ponor.
2068	sea water intrusion	See saltwater intrusion.
2069	sealing-grout, grout	Cement grout injected between a well casing and the borehole wall (annular space) to seal off an aquifer from external contamination.
2070	secondary interstices	Voids formed in a rock after the rock had been formed [16].
2071	secondary porosity	Porosity created after rock formation due to fracturing, leaching, etc.
2072	section	A plot of the shape and details of a cave in a particular intersecting plane, called the section plane, which is usually vertical [25].
2073	sediment	Material recently deposited by water, ice or wind, or precipitated from water [25].
2074	sedimentation	The deposition of solid disintegrated rock material by water, wind, or gravity transport [16].
2075	sediment transport	The transport of eroded rock material by moving water or wind [16].
2076	seep	1. An area, generally small, where water or oil percolates slowly to the land surface. See seepage and spring [22]. 2. To move slowly through small openings of a porous material [22].
2077	seepage	1. The infiltration or percolation of water through rock or soil to or from the surface and usually restricted to the very slow movement of ground water. 2. The fluid discharged at a seep [22]. 3. The amount of fluid discharged at a seep [22]. 4. The slow flow of water through a porous medium. 5. The movement of water in unsaturated soil [16].
2078	seepage water	See percolation.
2079	seepage face	A boundary between the saturated flow field and the atmosphere along which ground water discharges, either by evaporation or movement “downhill” along the land surface or in a well as a thin film in response to the force of gravity [22].
2080	seepage force	The frictional drag of water flowing through voids or interstices in rock causing an increase in the intergranular pressure (i.e. the hydraulic force per unit volume of rock or soil which results from the flow of water and which acts in the direction of flow).
2081	seepage line	1. The uppermost level at which flowing water emerges along a seepage face [22]. 2. The upper free water surface of the zone of seepage. Synonymous with line of seepage, phreatic line [22].
2082	seepage path	The trajectory of fluid particles in seepage flow [16].
2083	seepage rate	The rate of seepage flow [16].
2084	seepage spring; filtration spring	See spring, seepage.
2085	seepage surface	The outflow surface between water level and the intersection of the phreatic surface in a well [16].
2086	seepage velocity	See specific discharge.
2087	selenite	Blade-like crystals of gypsum [9].
2088	self-cleaning capacity	The capacity of a river to clean its water of pollutants over a given length of water course [16].
2089	selenite needles	A sulfate speleothem having the shape of a needle that grows from gypsiferous cave soils [13]. See also speleothem.
2090	semiconfined aquifer	See leaky aquifer.
2091	sepiolite	A cave mineral — Mg₄Si₆O₁₅(OH)₂·6H₂O [11].
2092	series	A subdivision of rock according to age at which they were laid down in a geologic epoch [16].
2093	setting of cement	The process of hardening of cement [16].
2094	settling basin	A basin used for the settling out of solids from suspension [16].
2095	settling velocity	The terminal velocity at which a particle will fall through a fluid [16].
2096	sewage	Domestic and municipal wastes [16].
2097	shaft	1. Vertical, or steeply inclined, sections of a cave passage, of enormously varied size. The world’s deepest known shaft is the entrance shaft of Brezno pod Velbom on the Kanin plateau, Slovenia; it is 501m deep, with no ledges. Much debate surrounds statistics on the depths of fully underground shafts, which may be broken by ledges, but among the deepest is a shaft about 430m deep in Italy’s Abisso di Monte Novegno [9]. 2. A cylindrical tube generally steep sided, that forms by solution and (or) collapse [10]. 3. A vertical passage in a cave [10]. 4. A vertical and usually large diameter hole penetrating geologic formations for access of subsurface points [16]. See jama, karst shaft. See also pit; pothole (definition 2.).
2098	shake; shakehole	(England; sometimes spelled shackhole.) 1. Term used mainly by cavers to indicate a doline, especially one formed by subsidence. 2. Hole formed by solution, subsidence, and compaction in loose drift or alluvium overlying beds of limestone [10]. 3. Small subsidence or suffosion doline formed in the glacial till overlying limestones in the northern Pennies. See jama.
2099	shall sand	Sand containing considerable amounts of clay and shale [16].
2100	shawl	Simple triangular-shaped curtain [10].
2101	shear plane	A plane along which failure of material occurs by shearing.
2102	shear stress	See stress, shear.
2103	sheet	A thin coating of calcium carbonate formed on walls, shelves, benches, and terraces by trickling water [10].
2104	sheet erosion	Erosion occurring over widespread tabular sedimentary or effusive rock [16].
2105	sheet jointing	Fracturing of tensile character, mostly in granitoid rocks, parallel to the land surface. Sheet jointing is developed either by load release or temperature differences.
2106	shield; cave shield	1. A thin circular disc of calcite projecting from a cave wall at any upward inclination, commonly a meter or more in diameter and with the underside draped with stalactites and curtains. The shield is actually a double disc with a thin central crack that acts as the continuation of a wallrock fracture. It grows by water moving up the crack under pressure and depositing calcite on both sides of its outer rim. Shields are rare, but Lehman Cave, Nevada, has more than a hundred of them [9]. 2. A disk-shaped speleothem standing edgewise at a high angle [10]. 3. A geologically stable and undisturbed continental block [16].
2107	shilin	A type of pinnacle karst formed on low plateau of gently dipping limestone; it is distinguished by densely packed pinnacles up to 25m high, fluted by sharp Rillenkarren. Known only in southern China, shilin (pronounced sherlin) translates as stone forest [9].
2108	shore	The zone of separation between land and moving water [16].
2109	show cave	A cave that has been made accessible to the public for guided visits [25].
2110	sieve analysis	The determination of the particle-size distribution of a soil, sediment, or rock by measuring the percentage of the particles that will pass through standard sieves of various sizes [6].
2111	sieve opening	The opening between the mesh wires of a sieve [16].
2112	sieve retention	The material retained on a sieve [16].
2113	silicate rock	Rock containing silica in predominant proportions [16].
2114	silicic acid	H₄SiO₄ monomeric acid [16].
2115	silicon dioxide	Silica (SiO₂.) See also quartz.
2116	Silikatkarren	(German) Granites and related rocks that possess small outcrop sculpturing such as rounded runnels. They are best developed in the humid tropics such as Malaysia [8].
2117	silt	A grain particle with a diameter that ranges between 0.005 to 0.05 mm [16].
2118	silting	The deposition of silt in wells, caves, or reservoirs [16].
2119	sima	(Spanish) Natural well that has vertical sides [10].
2120	similarity criteria	The conditions indicating under what circumstances a model and prototype are similar [16].
2121	simple hydrograph	A single peaked hydrograph [16].
2122	single outlet	A stream cutting through a divide (tributary basin) or outflow to the sea (major basin) [16].
2123	single rope technique	The practice of climbing up and down ropes with the help of ascenders and descenders. Abbreviation: SRT.
2124	sink; sinkhole	(American) 1. A point where a stream or river disappears underground. The sinking water may filter through a choke that excludes cavers, or may flow into an open horizontal cave or vertical shaft, and while active all of these may be termed sinkholes. The flow of water may be very small, but in full flood many sinkholes swallow flows of tens of cubic meters per second. The character of sink water (or swallet water, as it is commonly termed by hydrologists), flowing directly and rapidly into an open cave, distinguishes it from percolation water [9]. 2. General terms for closed depressions. They may be basin, funnel, or cylindrical shaped [10]. See also closed depression; doline; ponor; stream sink; sumidero; swallet; swallow hole.
2125	sinkhole plain	(American) Plain on which most of the local relief is due to closed depressions and nearly all drainage is subterranean [10].
2126	sinkhole pond	(American) Small lake in closed depression in limestone, due to an impervious clay floor or to intersection of depression with the water table [10]. See doline lake.
2127	sinking river, sinking stream	A small stream that disappears underground [10]. See also lost river; doline; ponor; sink; sinkhole; stream sink; sumidero; swallet; swallow hole.
2128	sinter	1. A rock or deposit formed by precipitation from natural water, often from a hot or cold spring. Calcareous sinter is calcium carbonate and is also known as tufa, travertine, and onyx marble. Siliceous sinter is silica and is also known as geyserite and fiorite [20]. 2. A mineral precipitate deposited by a mineral spring, either hot or cold. Siliceous sinter, consisting of silica, may be called geyserite and fluorite; calcareous sinter, consisting of calcium carbonate, may be called tufa, travertine, and onyx marble [10]. Synonyms: (French) concrétion; (German) Sinter, Kalktuff, Travertin; (Greek) asvestolithikos toffos; (Italian) concrezione; (Russian) otlozenija istocnikov; (Spanish) concreción; (Turkish) kaynak tüfü; (Yugoslavian) travertin, sedra, bigar, lehnjak. Related to travertine.
2129	siphon	1. Synonym for a sump, or a section of flooded cave passage, in common parlance. True siphons, where water flows first up and then down are rare in caves, as the fractures in limestone tend to disrupt the required hydraulics. They are, however, the origin of such intermittent springs as the Fontestorbes spring in France, and the Ebbing and Flowing Well at Giggleswick Yorkshire. Both flow in regular pulses when the siphon is full and working, only to cease when the siphon input is broken by air, as the upstream reservoir level drops. Their operation depends on critical flows and both operate only in favorable weather conditions [9]. 2. Gallery in form of an inverted “U” with water moving only under pressure when the siphon has completely filled up; the water head at the input end being higher than at the drainage point [20]. 3. In speleology, a cave passage in which the ceiling dips below a water surface [10]. Synonyms: (French) siphon; (German) Siphon; (Greek) siphon; (Italian) sifone; (Russian) sifon; (Spanish) sifon; (Turkish) sifon; (Yugoslavian) sifon, smrk. See also water trap.
2130	site characterization	Means the program of exploration and research, both in the laboratory and in the field, undertaken to establish the geologic conditions and the ranges of those parameters relevant to a particular site. Site characterization includes borings, surface excavations, excavation of exploratory shafts, limited subsurface lateral excavations and borings, and in situ testing at depth needed to determine the suitability of the site for a geologic repository, but does not include preliminary borings and geophysical testing needed to decide whether site characterization should be undertaken [22].
2131	skin effect	The effect of the zone of reduced permeability immediately around the borehole on transient flow phenomena in pumping tests [16].
2132	skrytyĭ karst, zakrytyĭ karst	(Russian) See closed karst.
2133	skylight	A hole in the roof of a cave passage through to the ground surface. It may be an inlet shaft, a section of collapse or a breach due to surface lowering [9].
2134	slickenside	1. A polished, commonly striated rock surface within a fault plane, produced due to friction during fault movement. The striae give an indication of the fault movement direction [9]. 2. A polished fault plane with grooves due to relative motion of fault blocks [16].
2135	sliding	1. The relative displacement of two bodies along a surface, without loss of contact between the bodies. 2. The downslope movement of rock and earth material [16].
2136	sling	A joined loop of rope or tape [25].
2137	slocker	Local term used in the eastern Mendip Hills, England for a swallet or stream sink [9].
2138	slope	The inclination of a surface [16].
2139	slump pit	A hollow in the clay fill of a cave floor caused by erosion beneath the fill [10].
2140	smithsonite	A cave mineral — ZnCO₃ [11].
2141	snow	Solid crystalline form of water [16].
2142	snow cover; snowpack	The accumulated height of snow covering a given area [16].
2143	snow line	A line connecting elevations above which snowpack remains throughout the year [16].
2144	snow sampler	A tube used for the taking of cylindrical snow samples through a snow profile [16].
2145	snowdrift	Snow accumulation due to wind transport [16].
2146	sod	Root system in a soil [16].
2147	soda straw	1. Proto-stalactite in which water flow down through the center of the straw. Upon entering a vadose cave passage, the change in the partial pressure of carbon dioxide cause CO₂ degassing and the slow precipitation of CaCO₃. The straw grows downwards as a result; water also flows down the outside of the straw causing the stalactite to grow outwards around the straw. 2. American name for straw stalactite [9].
2148	soddy karst	See subsoil karst.
2149	sodium	A naturally occurring element (Na).
2150	soil aggregate	Loosely cemented cluster of soil particles [16].
2151	soil air	The air that fills soil and rock interstices above the zone of saturation [10].
2152	soil bulk density	The mass of dry soil per unit bulk soil [22].
2153	soil-covered karst	See subsoil karst.
2154	soil mechanics	The science of dealing with the mechanical properties of soils [16].
2155	soil moisture	Subsurface liquid water in the unsaturated zone expressed as a fraction of the total porous medium volume occupied by water. It is less than or equal to the porosity [22].
2156	soil-moisture meter	A device used to record soil moisture in situ [16].
2157	soil-moisture suction	The negative pore pressure exerted by capillary forces [16].
2158	soil profile	A vertical section of the soil mantle usually with distinguishable soil horizons [16].
2159	soil sample	A sample of soil on which soil properties are to be determined [16].
2160	soil swelling	The volume increase of soil due to swelling of unsaturated clay particles when in contact with water [16].
2161	soil water	See soil moisture.
2162	soil-water pressure	The pressure (positive or negative), in relation to the external gas pressure on the soil water, to which a solution identical in composition with the soil water must be subjected in order to be in equilibrium through a porous permeable wall with the soil water [22].
2163	soilcover	A layer of soil material covering bedrock [16].
2164	soilwater zone	The upper portion of the zone of aeration containing soil water [16].
2165	solid matrix	An assembly of interconnected solid mineral grains surrounded by voids [16].
2166	solid volume	The volume of solid particles in a porous sample [16].
2167	solifluction	The slow flowage of mud streams in arctic regions.
2168	solubility	The total amount of solute species that will remain indefinitely in a solution maintained at constant temperature and pressure in contact with the solid crystals from which the solutes were derived [22].
2169	solum	The top layers of a soil profile [16].
2170	solute	The substance present in a solution in the smaller amount. For convenience, water is generally considered the solvent even in “concentrated” solutions with water molecules in the minority [22].
2171	solute transport	The net flux of solute through a hydrogeologic unit controlled by the flow of subsurface water and transport mechanisms [22].
2172	solution	1. Synonym for dissolution, except that the product of the solution (or dissolution) process, is also termed a solution, this being a combination of liquid and non-liquid (solid or gaseous) components that exists as a liquid [9]. 2. A homogeneous mixture of two or more components. In ideal solutions, the movement of molecules in charged species are independent of each other; in aqueous solutions charged species interact even at very low concentrations, decreasing the activity of the solutes [22]. 4. The change of matter from a solid or gaseous state to a liquid state by combination with a liquid [10]. 5. The result of such change; a liquid combination of a liquid and a nonliquid substance [10]. See corrosion.
2173	solution breccia	A mass of rock composed of angular to rounded fragments of rock that have accumulated by solution of surrounding or underlying carbonate. See also collapse breccia.
2174	solution flutes	See rillenkarren.
2175	solution lake	A lake whose origin is attributed largely to solution of underlying rock.
2176	solution notch	These form wherever humic soil borders on a very steep or vertical limestone surface. The rock becomes undercut by water rich in biogenic CO₂. In the cone karst of the humid tropics, foot caves occur which are over-sized enlargements of solution notches [3].
2177	solution pan	Shallow solution basin or closed depression formed on bare limestone, generally characterized by flat bottom and overhanging sides [10]. The initial form is a closed hollow created by a humus patch. It may have over-hanging side walls and a flat floor covered by algae and small pieces or broken rock. Diameters are rarely greater than 15 cm [3]. Synonyms: (German) Kamenitza or Kamenica, opferkeßel; (British) panhole; (Spanish) tinajita. See Kamenica.
2178	solution pipe	A vertical cylindrical hole attributable to solution, often without surface expression, filled with debris, such as sand, clay, rock chips, and bones [10]. Synonym: sand pipe. See also geologic organ.
2179	solution runnel	See Rinnenkarren.
2180	solution scarp	Escarpment formed by more active solution of lower area or by corrosional undercutting of the base of the escarpment [10].
2181	solution subsidence	1. Any subsidence due to solution of underlying rock but particularly the subsidence of parts of a formation into hollows or pockets of an immediately underlying soluble formation [10]. 2. A crater-like doline in rock other than karst limestone, formed by surface subsidence above solutionally enlarged fissures in a sub-surface karst limestone stratum [19]. Synonyms: (French) affaissement par dissolution; (German) Lösungstaschen, Lösungstrichter; (Greek) katakáthisma thiá thialíseos; (Italian) subsidenza per dissoluzione, subsidenza per suberosione; (Russian) prosedanie vsledstvie rastvorenija; (Spanish) subsidencia por disolucion; (Turkish) erime alçalımı; (Yugoslavian) korozivno urus̃avanje.
2182	sonar	A system for detecting obstacles by emitting sound and intercepting and interpreting echoes that bounce back. It is used by bats and also by oilbirds and some swiftlets when they fly in the darkness of caves [23].
2183	sorption	1. A general term used to encompass the process of absorption and adsorption [22]. 2. All processes which remove solutes from the fluid phase and concentrate then on the solid phase of the medium [22].
2184	sótano	(Spanish for cellar or basement.) Term used in Mexico for deep vertical shafts in limestone, which may or may not lead to a cave [10].
2185	spangolite	A cave mineral — Cu₆Al(SO₄)(OH)₁₂·3H₂O [11].
2186	species (singular or plural)	A group of plants or animals whose members breed naturally only with each other and resemble each other more closely than they resemble members of any similar group [23].
2187	specific capacity	The rate of discharge of water from a well per unit of drawdown. It is commonly expressed as gpm/ft or m3/day/m and varies with pumping test duration [6].
2188	specific conductance	A measure of the ability of water to conduct an electrical current expressed in micromhos per centimeter at 25°C [22].
2189	specific discharge	The rate of discharge of ground water per unit area of a porous medium measured at right angle to the direction of flow. Synonyms: Darcy velocity; seepage velocity.
2190	specific drawdown	The amount of drawdown per unit discharge in a well [16].
2191	specific gravity	The weight of a particular volume of water that a given body of rock or soil will hold against the pull of gravity to the volume of the body itself. It is usually expressed as a percentage [6].
2192	specific retention, water retaining capacity	The ration of the volume of water that a given body of rock or soil will hold against the pull of gravity to the volume of the body itself. It is usually expressed as a percentage [6].
2193	specific storage	The volume of water released from or taken into storage per unit volume of the porous medium per unit change in head [6].
2194	specific surface	The ratio of grain particle surface to the volume of grain particles [16].
2195	specific yield	The ratio of the volume of water that a given mass of saturated rock or soil will yield by gravity to the volume of that mass. This ratio is stated as a percentage [6].
2196	spelean	Of, pertaining to, or related to caves [10].
2197	speleogen	A secondary cave structure formed by dissolving, such as a dome pit or a scallop [10].
2198	speleogenesis	Although the term literally means the birth, origin or mode of formation of caves, the full extent of speleogenesis includes all the changes that take place between the inception and the eventual destruction of an underground drainage system. It includes development phases during which the active drainage voids are too small to be considered caves as normally defined, as well as phases when the cave no longer functions as a drain, is enlarging only by collapse and, eventually, is being totally removed [9].
2199	speleogenetics	The totality of all processes which effect the creation and development of natural underground cavities. These comprise corrosion, erosion, and incasion, but are also influenced by lithology, tectonics, and climate.
2200	speleologist	1. A scientist engaged in the study and exploration of caves, their environment, and their biota [10]. 2. Explorer of caves, caverns, and other underground openings especially in karst. Caver and potholer are slang terms [20]. Synonyms: (French) spéléologue; (German) Höhlenforscher, Speläologe; (Greek) speleologos; (Italian) speleologo; (Russian) speleolog; (Spanish) espeleólogo; (Turkish) speleolo, magarabilimci; (Yugoslavian) speleolog, spiljar, jamar.
2201	speleology	1. Scientific study of caves, including aspects of sciences, such as geomorphology, geology, hydrology, chemistry and biology, and also the many techniques of cave exploration [9]. 2. The scientific study, exploration, and description of caves, cave organisms, and related features [10]. 3. The branch of knowledge dealing with the study and exploration of underground caves [20]. 4. Study, exploration, and description of caves, caverns, and other underground cavities in karst and rarely in lavas or ice [20]. Synonyms: (French) spéléologie; (German) Höhlenforschung, Höhlenkunde; (Greek) speleologhia; (Italian) speleologia; (Russian) speleologija; (Spanish) espeleología; (Turkish) speleoloji, magarabilim; (Yugoslavian) speleologija, pećinarstvo, jamarstvo.
2202	speleothem	1. General term for all cave mineral deposits, embracing all stalactites, flowstone, flowers, etc. Most are formed of calcite whose precipitation processes, related mainly to carbon dioxide levels in the water, are the direct reverse of the dissolution of limestone. Climatic influences on dissolution processes ensure that speleothems are generally larger and more abundant in the caves of the wet tropics, which are typified by thick stalactites and massive stalagmites, in contrast to the straws and flowstones of alpine caves [9]. 2. General term for stalactites, stalagmites, moonmilk, helictites, and other secondary mineral deposits in caves and caverns [20]. 3. A secondary mineral deposit formed in caves, such as stalactite or stalagmite [10]. Synonyms: (French) concrétions cavernicoles; (German) Höhlenformation; (Greek) speleolithoma; (Italian) concrezione; (Russian) natecnia obrazovanija; (Spanish) concreción (estalagmítica o estalactítica); (Turkish) magara oluşugu; (Yugoslavian) sige. See also cave formations.
2203	spelunker	See caver.
2204	spelunking	See caving.
2205	spencerite	A cave mineral — Zn₄(PO₄)₂(OH)₂·3H₂O [11].
2206	sphalerite	A cave mineral — ZnS [11].
2207	spillway	A device that allows for the escape of excess water [16].
2208	Spitzkarren	(German) These are isolated projections that may be of a beehive form or may be sharply pointed and tend to lie between grikes and the strike ribs of bedding grikes [8]. See also grike; bedding grike; clint.
2209	Spitzkegelkarst	(German) Tropical karst topography containing sharply pointed residual limestone hills [10].
2210	splash cup	The shallow concavity in the top of a stalagmite [10].
2211	spongework	1. Randomly shaped cavities created by undirected phreatic dissolution in a massive, essentially homogeneous limestone. Fine examples occur in Carlsbad Caverns, New Mexico [9]. 2. An arrangement of partitioned depressions found in cave ceilings and walls, and attributed to the differential solution of submerged karst limestones. Larger and more isolated hollows are known as “pockets” [19].
2212	spongework cave pattern	A complex maze cave pattern consisting of irregular interconnecting cavities with intricate perforation of the rock. The cavities may be large or small. All spongework patterns are non-branching in development and contain profuse travertine. In map view, these caves often appear as an irregular ink blot.
2213	spontaneous potential	See self-potential.
2214	spore tracer	Dyes spores of the fern, Lycopodium clavatum, used to label ground water in karstic terranes. Synonyms: (French) traceur marqueur; (German) Sporenmarkierung; (Greek) lycopodium ichnithetis; (Italian) tracciante vegetale; (Spanish) trazador de esporas; (Turkish) spor izleyici. See isotope tracer, Lycopodium spores.
2215	spring	1. Point where underground water emerges on to the surface, not exclusive to limestone, but generally larger in cavernous rocks. The image of a trickle of water springing from a hillside hardly matches that of a vast cave pouring forth a river, but both are called springs. Among the world’s largest is the Dumanli spring, Turkey, with a mean flow of over 50 cubic meters per second. Springs may be exsurgences or resurgences, depending upon the source of their water, and also may be vauclusian in character [9]. 2. A natural outflow of water (or other liquid or gas) at the surface of the land or into surface water. In some usages, “spring” is restricted to the water which outflows, in other usages the word can refer to the water, the outlet, or to the locality of the outflow [20]. 3. Any natural discharge of water from rock or soil onto the surface of the land or into a body of surface water [10]. 4. A discrete place where ground water flows naturally from a rock or the soil onto the land surface or into a body of surface water [22]. Synonyms: (French) source; (German) Quelle; (Greek) pighi; (Italian) sorgente; (Russian) istocnik; (Spanish) fuente; (Turkish) kynak. See also seep.
2216	spring, artesian	Water flowing under artesian pressure with the potentiometric surface above the land surface [16].
2217	spring, barrier	A subsurface barrier forcing water to rise to ground surface and discharge as a spring [16].
2218	spring, boiling	1. An uncommon type of vauclusian spring, where the flow is large enough in a constricted site to form turbulence on the surface of the resurgence pool [9]. 2. (Jamaican) A. variable-discharge artesian spring in which hydrostatic pressure is great enough to cause a turbulent or even fountain-like discharge [19]. See also blue hole.
2219	spring, boundary	A spring located at the boundary between a permeable formation overlying an impermeable substratum [16].
2220	spring, cave	A spring rising in a cave [10].
2221	spring, contact	A spring formed at the intersection of the land surface and a permeable water- bearing formation overlying a less permeable formation [16].
2222	spring, depression	A spring originating at the intersection of the land surface with the water table [16].
2223	spring, drowned	A spring which continues to function as a spring after it has become submerged by rising sea or lake levels or by subsidence of the ground [20]. Synonyms: (French) source sous- aquatique, source noyé; (German) submarine Quelle, sublacustre Quelle; (Greek) vethisthesa pigi; (Italian) sorgente sommersa; (Russian) subakvaljnij istoćnik; (Spanish) fuente subacuática; (Turkish) batık kaynak; (Yugoslavian) potopljen izvor, potopljeno vrelo, potopljen izvir (vrelec). Related to spring, sublacustrine, and spring, submarine.
2224	spring, ebb-and-flow; ebbing-and-flowing well	A spring (flowing well or borehole) exhibiting periodic variation in volume of flow; this variation, which may be regular or irregular, is often attributed in karst regions to siphonic action. Ebb-and-flow springs differ from intermittent springs because the latter can be related to seasonal variations in rainfall [20]. Synonyms: (French) source intermittente; (German) intermittierende Quelle; (Greek) pighí ambótidos kai palírrias; (Italian) sorgente carsica intermittente; (Russian) sifonnij istocnik; (Spanish) manatial intermittente, fuente intermittente; (Turkish) sogultkan kaynak; (Yugoslavian) periodicni ixvor, periodic ̃ni izvir. See also spring, periodic. Related to intermittent spring.
2226	spring, fracture	A spring with its outflow openings consisting of fractures [16].
2227	spring, fullflow	A spring that is the sole drain of an area.
2228	spring, gravity	A spring flowing as a result of gravity [16].
2229	spring head alcove	The arcuate cliff surrounding many risings, formed by progressive headward sapping and cavern collapse. The rapidity of their formation is increased by the cliff-line which frequently exists already at the lower margin of the karst area [19].
2230	spring, intermittent	1. A karst spring with a pulsating flow, caused by the presence within the rock of cavities and siphons fed by a subterranean watercourse. When the cavity is full, the siphon is complete and causes a pulse of water to issue from the spring. This diminishes or empties the water supply in the cavity and no further water is discharged from the spring until the system is reactivated. The discharge is said to be a reciprocating spring when a reduced level of flow is maintained between pulses [19]. 2. A spring flowing at irregular intervals [16]. Synonyms: (French) source temporaire, source intermittente; (German) intermittierende Quelle, periodische Quelle; (Greek) thialepousa pege; (Italian) sorgente temporanea, sorgente intermittente; (Russian) peremezajuscijsja istoćnik; (Spanish) fuente intermitente, fuente temporal; (Turkish) kesintili kaynak; (Yugoslavian) periodicko vrelo, potajnica, obdobni izvir. Related to spring, ebb-and-flow; spring, periodic.
2231	spring, karst	A spring emerging from karstified limestone [10]. See also emergence; exsurgence; resurgence; rise.
2232	spring, medicinal	A spring with healing properties [16].
2233	spring, mineral	A spring having a high mineral content.
2234	spring, overflow	A spring that is part of a distributary but which drains only at the level above base flow.
2235	spring, perched karst	The emergence of underground water some where above the basement of a calcareous massif caused by the interbedding of an impermeable or intermittent perched water table by restricting the vertical movement of water, which instead issues from the contact [19].
2236	spring, perennial	Stream flowing above land surface throughout the year [16].
2237	spring, periodic	A spring that shows variation in flow that is either regular or irregular. It may be due to siphonic action [20]. Synonyms: (French) source périodique; (German) Periodische Quelle, intermittierende Quelle; (Greek) periodhiki piyi; (Italian) sorgente periodica; (Spanish) fuente periódica; (Turkish) periyodik kaynak; (Yugoslavian) periodic ̃ini izvor (izvir). See ebb-and-flow spring. Related to intermittent spring.
2238	spring, saline	Spring water having a high salt content [16].
2239	spring, seepage	A spring where surface discharge occurs from numerous small openings [16]. Synonym: filtration spring.
2240	spring, subaqueous	A spring that discharges below the surface of a water body (e.g. ocean, lake, river, or stream) [16].
2241	spring, sublacustrine	A spring emerging in the bed of a lake predominantly in karst areas [20]. Synonyms: (French) source sous lacustre; (German) Unterwaßerquelle, sublacustre Quelle; (Greek) ypovrichios pighi; (Italian) sorgente sublacustre; (Russian) istocnik na dne ozera; (Spanish) fuente sublacustre; (Turkish) gölalti kaynagı. See spring, drowned.
2242	spring, submarine	1. A spring emerging in a sea or lagoon predominantly in karst terranes. This is a descriptive term generally corresponding to the genetic term “drowned spring” [20]. 2. Large offshore emergence, generally from cavernous limestone, but in some areas from beds of lava [10]. Synonyms: (French) source sous marine; (German) Untermeeresquelle, Grundquelle, submarine Quelle; (Greek) ypothalassia pighi; (Italian) sorgente sottomarina; (Russian) submarinnij istocnik; (Spanish) fuente submarina; (Turkish) denizalti kaynagı; (Yugoslavian) vrulja. See spring, drowned.
2243	spring, thermal	A spring with temperature of the spring water above the average temperature of superficial rock [16].
2244	spring, tubular	A spring issuing from a round channel such as a tubular passage [16].
2245	spring, unconformity	A spring issuing at the contact of an aquifer with an unconformity.
2246	spring, underflow	A spring that is part of a distributary but which is at lower elevation and preferentially drains base flow. Between it and an overflow spring there may be several underflow-overflow springs.
2247	spring, valley	Springs occurring at valley sides where the water table intersects the land surface.
2248	spring, vauclusian; rising, vauclusian	1. A type of rising or spring where direct drainage from the phreas flows up a flooded cave passage under pressure to emerge in daylight. The term is best applied where water rises from a vertical or very steep bedrock passage. Such risings are named after the Fontaine de Vaucluse in southern France. The River Sorgue rises from the Fontaine with a mean flow of 26 cubic meters per second. Its upper part is steeply inclined, but at depth it is vertical. A diver has reached a depth of –200m, and a robot reached –243m, below which the flooded shaft continues [9]. 2. Large karst spring (name by Fournet, after la Sorgue en Vaucluse, France) characterized by a stream surging up as from a siphon. Also applied to karst springs with artesian characteristics [20]. 3. A large spring or exsurgence of an underground river, generally from limestone, that varies greatly in output and is impenetrable except with diving apparatus [10]. Synonym: (American) gushing spring; (French) source vauclusienne, bouillidou (South of France); (German) Vauclusequelle, (Riesenquelle); (Greek) kephalari/vauclusiana pighi; (Italian) sorgente valchiusana; (Russian) vokljuz; (Spanish) fuente vauclusiana, ojo, heryidero; (Turkish) basınçclı kaynak; (Yugoslavian) voklisko vrelo, obrh. See also gushing spring.
2249	squeeze	A narrow passage or opening just passable with effort. Differs from flattener in that there is little spare space in any direction [10].
2250	staff gage	A fixed graduated scale [16].
2251	stage	Water surface elevation at a point along a stream, river, lake, etc., above an arbitrary datum [16].
2252	stage-discharge relation	See rating curve.
2253	stage hydrograph	The elevation of stage plotted against time [16].
2254	stage record	Stage discharge relations presented in tabulated form [16].
2255	stagmalite	A general term including stalactite and stalagmite. Superseded by dripstone [10].
2256	stagnation point	The foremost point on a streamline dividing an area of pumping depression from a zone of influence in a tilted aquifer being pumped by a well [16].
2257	stalactite	1. Speleothem, generally of calcite, formed by dripping water and hanging from a cave roof. Stalactites embrace an enormous variety of sizes and shapes. They form where percolation water seeps from a cave ceiling and becomes saturated with respect to calcite due to loss of carbon dioxide into the cave air. Calcite is precipitated round the rim of the water droplet and continued deposition creates a hollow tubular straw stalactite (soda straw). Additional deposition of calcite on the outside of the initial cylinder creates an ordinary tapering stalactite. Almost infinite variation in shape may be influenced by changes in water flow, cave air chemistry, evaporation, temperature or dissolved impurities, and by crystal growth blocking flow paths. They are the most common speleothem. Though the single 7m long stalactite in Ireland’s Poll an Ionain is not the world’s longest, it is uniquely spectacular against the dark chamber walls [9]. 2. Conical deposit of calcite or aragonite often with a hollow center hanging from the roof of a cave or cavern formed by precipitation of carbonate due to escape of CO₂ from hanging water beads and to evaporation of part of the water [20]. 3. A cylindrical or conical deposit of minerals, generally calcite, formed by dripping water, hanging from the roof of a cave, generally having a hollow tube at its center. From Greek word meaning exude drops [10]. Synonyms: (French) stalactite; (German) Tropfstein, Stalaktit; (Greek) stalaktitis; (Italian) stalattite; (Russian) stalaktit; (Spanish) estalactita; (Turkish) sarkıt (Yugoslavian) mosur, viseci kapnik, stalaktit.
2258	stalagmite	1. Speleothem, normally of calcite, formed by upward growth from a cave floor, and therefore the complement of a stalactite. Stalagmites form when dripwater that is still saturated falls from a cave roof or stalactite and, when or after it lands, loses more carbon dioxide to the cave air, causing precipitation of calcite. They vary in size and shape, from tall thin towers to wide domes that grade into flowstone, the main controls being drip rate and height, and saturation levels of the water. The stalagmites of Aven Armand, France, are of the multiple splash-cup variety while being notably slender and up to 30m tall. Spectacularly massive stalagmites occur in the Carlsbad and Cottonwood Caves of New Mexico [9]. 2. Columnar or partly irregular deposit of calcite or aragonite on the floor of a cave or cavern formed by the precipitation of carbonates due to escape of CO₂ from water dripping from the roof [20]. 3. A deposit of calcium carbonate rising from the floor of a limestone cave, formed by precipitation from a bicarbonate solution through loss of CO₂. The water drops on the stalagmite from above. From Greek word meaning drip [10]. Synonyms: (French) stalagmite; (German) Bodenzapfen, Stalagmit; (Greek) stalagmitis; (Italian) stalagmite; (Russian) stalagmit; (Spanish) estalagmita; (Turkish) dikit; (Yugoslavian) óulak, stoječi kapnik, stalagmit. See also dripstone.
2259	stalagmite, capillary	See capillary stalagmite.
2260	standard deviation	A measure of variability of the square of individual deviations from their mean [16].
2261	standing line	A rope of approximately 0.4375 inches or 11 mm in diameter that is tied to a solid anchor and is used for descending and ascending [13]. See also ascender; knot; mechanical ascender; prusik knot; prusiking.
2262	state of solution	The degree to which a mineral or rock has gone into solution [16].
2263	static head	See head, static.
2264	static water level	The level of water in a well that is not being affected by withdrawal of ground water [6].
2265	station	A survey point in a chain of such points in a survey [25].
2266	steady flow	Flow where the velocity at a point remains constant with respect to time [16].
2267	steam hole	An opening from a cavity through which a current of air charged with vapor blows upwards and condenses at the orifice to appear as steam. Such openings are an occasional feature in karst terranes [20]. Synonyms: (French) puits à vapeur, puits fumant; (German) Dampfschlot; (Greek) atmotrypa; (Spanish) cavidad fumante; (Turkish) buhar deligi.
2268	steep	The property of inclination with a very steep gradient [16].
2269	steephead	A deeply cut valley, generally short, terminating at its upslope end in an amphitheater, at the foot of which a stream may emerge [10].
2270	stegamite	A speleothem projecting upwards from a cave floor in the form of a calcite ridge. A medial crack appears along the top of the ridge where water is thought to be forced from the speleothem under capillary action [25].
2271	stemflow	Rain water flowing down the stem of plants [16].
2272	stereo aerial photographs	Aerial photographs shot in sequence over a landscape so that when adjoining photos are viewed at the proper interpupillary spacing, features may be seen in three- dimensions.
2273	stereogram	A block diagram or three-dimensional diagram [16].
2274	stilling well	A well connected to a flowing stream or spring through a bottom conduit permitting elevation measures to be taken in quiescent water [16].
2275	stomatal transpiration	The transpiration by escape of water through pores (stomata) of leaves [16].
2276	stone forest	See shilin.
2277	stoping	The upward migration of the ceiling in a passage or room by the action of slabs falling [13].
2278	storage capacity	1. The ability of an aquifer to store water [16]. 2. The capacity of rivers to store water in their own channel [16].
2279	storage coefficient	1. The volume of water an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in head [22]. In a confined aquifer, the water is derived from storage with decline in head resulting from an expansion of the water and compression of the aquifer. Similarly, water added to storage with a rise in head is accommodated partly by compression of the water and partly by expansion of the aquifer. In an unconfined aquifer, the amount of water so released or accepted is generally negligible compared to the amount involved in gravity drainage or filling of pores, hence, in an unconfined aquifer, the storage coefficient is virtually equal to the specific yield. 2. The volume of water an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in head (virtually equal to the specific yield in an unconfined aquifer.) 3. The volume of water a confined hydrogeologic unit releases from or takes into storage per unit subsurface area of the hydrogeologic unit per unit change in head.
2280	storage gage	A precipitation gage for collecting and storing the total amount of inflowing water to be read at long intervals [16].
2281	storage in depressions	Water retention in surface depressions [16].
2282	storativity	See storage coefficient.
2283	storm	1. A disturbance of average meteorological conditions and usually connected with precipitation [16]. 2. A period of precipitation over a specific drainage basin [16].
2284	strath terrace	An erosional remnant of an elevated broad river valley [16].
2285	stratification	1. A depositional structure of sedimentary rocks in beds and layers [16]. 2. The separation into non-discrete layers of water as a result of chemical, saline, or temperature differences which in turn create density differences in the water.
2286	stratigraphic column	A graphic means of representing the various rock types of an area in a geologic report [13].
2287	stratigraphic sequence	The sequence of rock types in an area [13].
2288	stratum	A sedimentary bed or layer [16].
2289	straw stalactite; straw	1. The simplest form of stalactite — a fragile, thin walled tube, normally of calcite, which is the diameter of the drops of water that hang from its end and continue its growth. Though only about5mm in diameter, straw stalactites (or straws) may grow to great length in clusters of spectacularly dense profusion, more commonly in caves of cooler climates. The length record may be held by a 6m straw in Easter Cave, Western Australia. Also known as straw stalactite or soda straw [9]. 2. Thin tubular stalactite, generally less than a centimeter in diameter and of very great length (examples as long as 4 meters); also called soda straw [10]. See also soda straw; stalactite.
2290	stream	A body of flowing water [16].
2291	stream bed	The bottom of a stream covered by water [16].
2292	stream development	The ratio of actual tortuous stream length between two points on a straight line connecting these points [16].
2293	stream flow	The total runoff confined in a stream and its’ channel [16].
2294	stream frequency	Channel frequency; the number of stream segments per unit area [16].
2295	stream order	The hierarchic order of stream segments according to tributaries [16].
2296	stream profile	The elevation of the main stream bed as a function of distance from outflow.
2297	stream sink, streamsink	Point at which a surface stream sinks into the ground [10]. See also doline; ponor; sink; sinkhole; sumidero; swallet; swallow hole.
2298	stream tube	1. A cave passage completely filled, now or in the past, with fast-moving water and whose ceiling and walls normally show scallops [10]. 2. The imaginary space formed between two adjacent streamlines in which flow is constant (assuming steady flow conditions). Synonyms: (French) conduite forcée; (German) Druckflußrohr; (Greek) ypóghios síranx; (Italian) condotta forzata; (Spanish) tubo (o conducto) fréatico; (Turkish) akarsu mecrası. See conduit, pressure flow tube.
2299	streamline	A curve that is everywhere tangent to the specific discharge vector and indicates the direction of flow at every point in a flow domain.
2300	streamtube	A cave passage completely filled, or formerly filled, with fast-moving water and whose ceiling and walls normally possess scallops [10].
2301	strength	The maximum stress which a material can resist without failing for any given type of loading.
2302	stress	The force acting across a given surface element divided by the area of the element.
2303	stress, applied	The downward stress imposed at an aquifer boundary. It differs from effective stress in that it defines only the external stress tending to compact a deposit rather than the grain- to-grain stress at any depth within a compacting deposit [21].
2304	stress, effective	Stress (pressure) that is borne by and transmitted through the grain-to-grain contacts of a deposit, and thus affects its porosity or void ratio and other physical properties. In one-dimensional compression, effective stress is the average grain-to-grain load per unit area in a plane normal to the applied stress. At any given depth, the effective stress is the weight (per unit area) of sediments and moisture above the water table, plus the submerged weight (per unit area) of sediments between the water table and the specified depth, plus or minus the seepage stress (hydrodynamic drag) produced by downward or upward components, respectively, of water movement through the saturated sediments above the specified depth. Thus, effective stress may be regarded as the algebraic sum of the two body stresses, gravitational stress, and seepage stress. Effective stress mal also be regarded as the difference between geostatic and neutral stress [21].
2305	stress, geostatic	The total load per unit area of sediments and water above some plane of reference. It is the sum of (1) the effective stress, and (2) the neutral stress [21].
2306	stress, neutral	Fluid pressure exerted equally in all directions at a point in a saturated deposit by the head of water. Neutral pressure is transmitted to the base of the deposit through the pore water, and does not have a measurable influence on the void ratio or on any other mechanical property of the deposits [21].
2307	stress, preconsolidation	The maximum antecedent effective stress to which a deposit has been subjected, and which it can withstand without undergoing additional permanent deformation. Stress changes in the range less than the preconsolidation stress produce elastic deformations of small magnitude. In fine-grained materials, stress increases beyond the preconsolidation stress produce much larger deformations that are principally inelastic (nonrecoverable) [21].
2308	stress, seepage	When water flows through a porous medium, force is transferred from the water to the medium by viscous friction. The force transferred to the medium is equal to the loss of hydraulic head. This force, called seepage force, is exerted in the direction of flow [21].
2309	stress, shear	Stress directed parallel (tangential) to the surface element across which it acts.
2310	strike	The direction or azimuth of a horizontal line in the plane of an inclined stratum, joint, cleavage plane or other planar feature within a rock mass.
2311	strike valley	A valley following the strike of underlying strata [16].
2312	structure	One of the larger features of a rock mass (e.g., bedding, foliation, jointing, cleavage, brecciation, etc.). Also the sum total of such features as contrasted with texture. In a broader sense, it refers to the structural features of an area such as anticlines or synclines.
2313	structural factor	Features modifying or interrupting the continuity of rock types [16].
2314	structural geology	That part of geology dealing with structures formed in rocks [16].
2315	struga	(Slavic) A corridor formed along a bedding plane in karst country [10].
2316	stygobite	An aquatic troglobite [23].
2317	stygophile	An aquatic troglophile [23].
2318	stygoxene	An aquatic trogloxene [23].
2319	stylolite	An irregular suture-like boundary developed along some bedding planes in limestones, probably caused by dissolution under pressure and possibly related in some cases to subsequent inception of speleogenesis[9[.
2320	subaqueous spring	See spring, subaqueous.
2321	subaqueous karst	A karst terrane that is covered by a discrete body of water [17]. See also drowned karst; subfluvial karst; submarine karst.
2322	subartesian well	An artesian well with insufficient head to raise water above the land surface [16].
2323	sub-conduit	Any void, whether of tectonic or dissolutional origin, that is smaller than the accepted defined size of a conduit. Sub-conduits originate under inception conditions and enlarge during gestation, but many fail to achieve larger dimensions when drainage later becomes concentrated along preferred routes. In most cases, however, they will continue to function as part of the micro-fissure, or percolation, system within the rock mass. Sub-conduits are an essential part of a continuum of void sizes that extends between microscopic discontinuities and the largest tube passages [9].
2324	subcutaneous drain	Discrete percolation drains contained within the epikarst zone and leading to the transitions zone. See also epikarst zone; subcutaneous flow; subcutaneous zone; transition zone.
2325	subcutaneous flow	Lateral and vertical flow that occurs within the epikarst zone under saturated conditions. Lateral flow distances can exceed hundreds of meters and several meters per day while vertical within discrete percolation drains (subcutaneous drains) may allow flow rates in excess of several hundred meters per hour. See also epikarst zone; subcutaneous drain; subcutaneous zone; transition zone.
2326	subcutaneous zone	Synonym for epikarst zone. See epikarstic zone.
2327	subfluvial karst	Karst topography developed beneath a river. See also subaqueous karst.
2328	subjacent karst	Karst landscape in noncarbonate rocks due to presence of karstified rocks beneath the surface formation [10]. Synonyms: (French) karst sous-jacent; (German) unterirdisches Karstphänomen; (Greek) ypokímenon karst; (Russian) pokritij karst; (Spanish) karst subyacente; (Turkish) gizli karst; (Yugoslavian) pokriven krs̃ (kras). See also interstratal karst.
2329	subkutan karst	See subsoil karst.
2330	sublacustrine spring	See spring, sublacustrine.
2331	sublimation	The direct conversion of water from its solid state to the vapor phase [16].
2332	submarine karst	Karst topography developed below the tidal zone. See also subaqueous karst.
2333	submarine spring	See spring, submarine.
2334	subpermafrost karst	Underground karst in areas of permafrost. Karstification is due to the solvent action of subpermafrost (or intrapermafrost) water [20]. Synonyms: (French) karst sous- permafrost; (German) Pseudokarst; (Greek) karst ypomonímou paghetoú; (Italian) carsismo di subpermafrost; (Russian) podmerzlonij karst, mezmerzlotnij karst; (Spanish) karst de subpermafrost, karst de intrapermafrost; (Turkish) don alanı yeraltı karstı. See permafrost karst. See also intrapermafrost karst.
2335	subpermafrost water	Ground water below the permafrost [16].
2336	subsequent river	1. A river flowing along the strike of a weak formation [16]. 2. A tributary to a consequent river [16].
2337	subsidence	Lowering of the surface of the ground because of removal of support. Caused in karst areas by subterranean solution or collapse of caves [10].
2338	subsidence doline	A closed karst depression formed due to local subsidence of the surface rocks and/or soil into cavities formed by widespread dissolution or local collapse of caves. The type of subsidence doline formed by downwashing of the soil cover is better described as a suffosion doline [9]. Also known as sinkhole.
2339	subsidence/head-decline ratio	The ratio between land subsidence and hydraulic head decline in the coarse-grained beds of the compacting aquifer system [21].
2340	subsoil karst	Karst covered by soil, usually residual soil [17]. Synonyms: (British) soddy karst; (French) karst vert, karst subcutané; (German) bedeckter Karst, bodenbedeckter Karst, grükarst, subkutan karst; (Greek) ypethaphikon karst; (Russian) zadernovannyĭ karst; (Spanish) karst subcutáneo; (Turkish) toprakaltı karstı; (Yugoslavian) pokriveni krs̃ (kras). See also covered karst.
2341	subsurface divide	See underground divide.
2342	subsurface flow	See subsurface runoff.
2343	subsurface runoff, storm seepage, subsurface flow, subsurface storm flow	Runoff due to infiltrated precipitation moving laterally under the surface.
2344	subsurface water	All water that occurs below the land surface [22].
2345	subterranean	Beneath the land surface [16].
2346	subterranean cut-off	The diversion underground of a surface watercourse beneath a surface meander neck, marked by a swallow hole on the upstream side and a spring on the downstream side [19]. See also stream piracy.
2347	subterranean river, subterranean stream	Underground stream of flowing water in caves and caverns, but not necessarily large [10]. See also underground stream.
2348	suction	See moisture tension.
2349	suffosion	Undermining through removal of sediment by mechanical and corrosional action of underground water [20]. Synonyms: (French) soutirage karstique; (German) Anzapfung; (Greek) ypoghion thiavrosis; (Russian) suffozija; (Spanish) sufosión; (Turkish) karstik yeraltısuyu kazıması; (Yugoslavian) sufozija.
2350	suffosion doline	More accurate synonym for a type of subsidence doline, indicating formation by the suffosion, or downwashing, of the soil into an underlying fissure [9]. Also known as shakehole.
2351	sulfate	A mineral compound characterized by the sulfate radical SO₄²⁻. Anhydrous sulfates, such as barite, BaSO₄, have divalent cations linked to the sulfate radical; hydrous and basic sulfates, such as gypsum, CaSO₄.2H₂O, contain water molecules [1].
2352	sulfate minerals	Minerals containing the SO₄²⁻ radical, formed by precipitation from water. The most common are the anhydrous and hydrated calcium sulfates, anhydrite (CaSO₄) and gypsum (CaSO₄.2H₂O). Sulfates are deposited as a generally minor component of most carbonate successions, but due to their high solubility they may not survive subsequent dissolution by ground water. Even if they survive subsequent dissolution by ground water. Even if they survive at depth, they tend to dissolve as they are raised nearer to the surface following uplift and erosion of overburden. Removal of sulfates by dissolution may contribute to the early establishment of secondary permeability in limestone sequences. Sulfate solutions have a limited corrosional effect upon calcium carbonate, but may also be oxidized to produce sulphuric acid, which is highly corrosive of limestone.
2353	sulfate-reduction karst	Karst topography developed in the subsurface where solution of bedrock is chiefly a result of sulfate reduction by petroleum hydrocarbons aided by bacterial processes that oxidize hydrocarbons to yield carbon dioxide. Little, if any of the water that dissolves the rock is meteoric [17].
2354	sulfide	A mineral compound characterized by the linkage of sulfur with a metal or semimetal, such as galena, PbS, or pyrite, FeS₂ [1]. See also gypsum and pyrite.
2355	sulfide minerals	Minerals that are composed of one or more metals combined with sulphur. The most common is pyrite. They are believed to be produced by the metabolic action of micro- organisms, and are found in many sedimentary rocks, usually in trace amounts.
2356	sumidero	(Spanish) 1. A swallow hole. 2. In Latin America, any closed depression caused by solution [10].
2357	summation curve	A curve of cumulated values [16].
2358	summit	The highest point of a physiographic feature [16].
2359	sump	1. In caves a sump is a section of flooded passage. This may be a perched sump, probably quite short, within a vadose cave and created by a local reverse passage gradient. Alternatively it may be a major feature, where a cave passage descends below the regional water table into the phreas, as is common at the lower end of many cave systems. Some short sumps can be dived without the use of breathing apparatus, but most are restricted to exploration by cave divers. Logistics are a barrier to endless sump penetrations, but some have now been explored for many kilometers in length, notable in Cocklebiddy Cave, Australia, the Nohoch Nah Chich and other great flooded systems in Mexico’s Yucatan, and behind Keld Head in Yorkshire [9]. 2. A pool of underground water or point on an underground stream that has a submerged extension, the nature of which has not been determined [10]. 3. A place where the ceiling of a passage drops to and below water level in a cave, leaving no air space with the cave passage continuing underwater [13]. 4. A water trap.
2360	sulfuric acid	An acid (H₂SO₄).
2361	sunken pan	An evaporation pan buried in the ground for equal elevation of the water surface with the ground surface [16].
2362	superimposed valley	A valley established on the land surface with a pattern that is independent of the underlying rock structure.
2363	supersaturated	Referring to water that has more limestone or other karst rock in solution than the maximum corresponding to normal conditions [25].
2364	supersaturation	A liquid that is over saturated with respect to whatever particles may be contained in the fluid.
2365	suprapermafrost karst	Surface karst in areas or permafrost. Karstification is due to the solvent action of suprapermafrost water [20]. Synonyms: (French) karst suprapermafrost; (German) Pseudokarst; (Greek) karst epi monímou paghetoú; (Italian) carsismo superficiale di permafrost; (Russian) nadmerzlotnij karst; (Spanish) karst de suprapermafrost; (Turkish) don alanı yüzey karstı. See also permafrost karst.
2366	suprapermafrost water	Ground water above permafrost [16].
2367	surf karren	Surf karren form along marine limestone and dolomite coasts where the surf sprays water onto abrasion surfaces that lie slightly above normal sea level. They are a result of corrosion caused by the mixing of sea- and rainwater, but do not exist under the sea surface as seawater is not limestone-corrosive. Beyond the splashwater zone the karren are much less sharp [3].
2368	surfactant	A substance capable of reducing the surface tension of a liquid in which it is dissolved. Used in air-based drilling fluids to produce foam, and during well development to disaggregate clays [6]. Surfactants are now being considered for the purpose of aquifer remediation by helping disperse immiscible contaminants.
2369	surface detention	Sheet flow of water in overland flow before a channel is reached [16].
2370	surface entry	An opening immediately at the land surface that permits infiltration to take place [16].
2371	surface film	A monomolecular film of organic compounds forming on water or grain surfaces [16].
2372	surface mapping	The topographic and geodetic mapping of an area [16].
2373	surface mine	Strip mine [16].
2374	surface retention	Water held on land surface [16].
2375	surface runoff	That part of runoff traveling over the ground surface and through channels [16].
2376	surface seepage	Surface discharge of ground water not important enough to form a rivulet [16].
2377	surface spreading	A method of artificial recharge of water to an aquifer by spreading on a surface [16].
2378	surface tension	The free specific surface energy occurring at the interface between a liquid and its own vapor phase [16].
2379	surface water	Water obtained from surface supplies [16].
2380	survey	In caving, the measurement of directions and distances between survey points and of cave details from them, and the plotting of cave plans and sections from these measurements either graphically or after computation of coordinates [25].
2381	susica	Yugoslavian term for intermittent stream or river in a karst terrane in which the water diverts and soaks gradually into the karst ground-water system [20]. See also intermittent river.
2382	suspended load	Detrital matter being transported in suspension by a moving stream [16].
2383	suspended matter	Solid matter small enough to be held in suspension by moving or stagnant water [16].
2384	suspended water	See vadose water.
2385	sustained yield	The rate at which water can be withdrawn from an aquifer without depleting the supply [16].
2386	suunto clinometer®	A small, handheld pendulum clinometer commonly used in cave survey [25].
2387	suunto compass®	A small, handheld sighting compass commonly used in cave survey [25].
2388	swale	A marshy depression or depression in a ground moraine [16].
2389	swallet, swallow hole	(British) A place where water disappears underground in a limestone region. A swallow hole generally implies water loss in a closed depression or blind valley, whereas a swallet may refer to water loss into alluvium at a streambed, even though there is no depression [10]. See also doline; ponor; sink; sinkhole; stream sink; sumidero.
2390	swelling	The volume increase due to intake and absorption of water, especially clays [16].
2391	swelling rate	The time rate of volume increase [16].
2392	swirlhole	A hole in rock in a streambed eroded by eddying water, with or without sand or pebble tools [25].
2393	synclinal valley	A valley following the axis of a syncline [16].
2394	syncline	Downfolded stratum [16].
2395	syngenetic karst	1. Karst developed contemporaneously with the lithification of the formation, as in eolian calcarenite where lithification and karstification of dune sands may proceed simultaneously [10]. 2. Karst landforms that developed upon young, porous carbonate rocks, such as aeolianites, as they underwent lithification [9]. Synonyms: (French) karst syngénétique; (German) Syngenetischer Karst; (Greek) synegeticon karst; (Italian) carsismo singenetico; (Spanish) karst singenético; (Turkish) eştürümlü karst; (Yugoslavian) singenetski krs̃ (kras).
2396	syngenite	A cave mineral — K₂Ca(SO₄)₂·H₂O [11].
2397	synoptic network	A network of first order stations permitting the regular observation of weather for all points at the same time [16].
2398	synthetic unit hydrograph	A unit hydrograph constructed by assuming the reaction of a drainage basin will be based on its physical characteristics [16].
2399	table mountain	A flat topped mountain (mesa) [16].
2400	tafoni	Roughly hemispherical hollows weathered in rock either at the surface or in caves [25].
2401	tagging	Affixing a metal tag bearing a cave number near its entrance, normally by means of rock drill and a small nail [25].
2402	tailwater	The lower course of a river with respect to a given point of structure [16].
2403	talus cone	A cone-like collection of disintegrated rock material originating from and adjacent to a steeper slope [16].
2404	tape	1. In survey, a graduated tape of steel, plastic, wire-reinforced cloth, or fibreglass, used for measuring distance. 2. Strips of woven synthetic fibre used for slings and waist bands [25].
2405	taranakite	A cave mineral — KAl₃(PO₄)₃(OH)·9H₂O [11].
2406	tarbuttite	A cave mineral — Zn₂(PO₄)(OH) [11].
2407	taylorite	A cave mineral — (K,NH₄)₂SO₄ [11].
2408	tectokarst	Karst formed under the strong influence of tectonic disturbances. The term is indefinite and its use is not generally recommended [20]. Synonyms: (French) tectokarst; (German) Tektonischer Karst; (Greek) tektonikon karst; (Russian) karst zon tektoniceskih razlomov; (Spanish) tectokarst; (Turkish) tektonik karst; (Yugoslavian) tektokrs̃, tektokras, tektokarst.
2409	tectonic	Pertaining to structural features due to the deformation of the crust [16].
2410	tectonic cave	A cave formed by some form of ground movement. The most common is due to landsliding in a jointed rock, leaving an open fissure cave parallel to the line of the hillside along the back of the slipped block. Tectonic caves can form in any rock, as they do not depend on dissolution. Well known examples are the windypit fissures of north-east Yorkshire, England some of which are hundreds of meters long and up to 60m deep [9].
2411	tectonic valley	A valley formed by tectonic forces [16].
2412	temperature efficiency	An efficiency factor defined by Thornthwaite for different climates. See also Thornthwaite.
2413	temperature log	A recording curve of ground-water temperature in a well [16].
2414	temporary hardness	See carbonate hardness.
2415	tenorite	A cave mineral — CuO [11].
2416	tensiometer	A device used to measure the moisture tension in the unsaturated zone [22].
2417	terminal moraine	A glacial deposit accumulated in front of a glacier [16].
2418	terra rossa	1. Reddish-brown soil mantling limestone bedrock; may be residual in some places [10]. 2. Insoluble residuum of a reddish-brown color left behind when carbonate rocks weather under Mediterranean or allied climatical conditions [20]. Synonyms: (French) terra rossa; (German) Kalksteinroterde; (Greek) erythroghi; (Italian) terra rossa; (Russian) terra-rossa; (Spanish) terra rossa; (Turkish) kızıl toprak, terrarosa; (Yugoslavian) crvenica, jerina, jerovica.
2419	terrace	A flat surface bounded by steplike steep slopes [16].
2420	terraced flowstone	Shallow rimstone pools on outward-sloping walls [10]. See also rimstone barrage; rimstone barrier; rimstone dam; constructive waterfall.
2421	terrain	An area with some specific characteristics. Reserved for surficial features only. Contrast with terrane.
2422	terrane	An area with some specific characteristics [16]. Includes both surface and subsurface features. Contrast with terrain.
2423	terrestrial	Living on land. Not to be confused with “epigean.” Terrestrial cave animals include blind beetles, rnillipedes, spiders, and crickets [23]. See also aquatic.
2424	tertiary porosity	See porosity, tertiary.
2425	test hole	A hole to test the depth of ground water, water quality, or geological conditions [16].
2426	texture	The arrangement in space of the components of a rock body and of the boundaries between these components [16].
2427	thalweg	A line of maximum depth of stream cross section [16].
2428	Theis equation	The nonequilibrium equation of radial flow towards a well [16].
2429	thenardite	A cave mineral — Na₂SO₄ [11].
2430	thermal spring	See spring, thermal.
2431	thermal stratification	The stratification of water in reservoirs due to thermal-density differences [16].
2432	thermocline	An intermediate layer in stratified water [16].
2433	thermocouple	A temperature measuring device based on the proportionality between thermoelectric current and temperature difference between thermojunctions [16].
2434	thermokarst	1. A pitted periglacial or former periglacial surface in superficial deposits, produced by settling or caving of the ground after melting of ground ice [10]. 2. A term applied to topographic depressions in karstic terranes resulting from the thawing of ice. See cryokarst.
2435	thermokarst pit	Steep-walled depression formed by thermokarst processes [10].
2436	thickness	The perpendicular distance between bounding surfaces such as bedding or foliation planes of a rock.
2437	thief zone	The zone through which drilling fluid is lost into a formation through the borehole wall [16].
2438	Thiem equation	The equation that describes steady-state equilibrium radial flow into a well [16].
2439	thixotropy	The property of a gel to become fluid under application of shear stresses [16].
2440	thread	A natural hole through a rope, tape or wire can be passed to create an anchor [25].
2441	threshold	That part of a cave system to which light penetrates in some degree [10].
2442	threshold saturation	Saturation below which no flow occurs [16].
2443	through cave	Cave through which a stream runs from entrance to exit or formerly did so [10]. Synonym: (German). Durchgangshöhle.
2444	throughfall	A part of precipitation that reaches ground by falling through vegetative cover [16].
2445	throw	The vertical displacement of stratum along a fault plane [16].
2446	thrust; thrust fault	A generally gently dipping or subhorizontal fault plane where the relative movement has been essentially horizontal, with one rock sequence being pushed across and above another. Some cave development in the Traligill area of north-west Scotland has been guided by thrust planes [9].
2447	tidal river	A river strongly influenced and subject to tidal currents [16].
2448	tidewell	See spring, ebb-and-flow.
2449	tightest packing	An arrangement of particles allowing only minimum void space a unit cell of a sample [16].
2450	till	Predominantly unsorted and unstratified drift, generally unconsolidated, deposited directly by and underneath a glacier without subsequent reworking by meltwater, and consisting of a heterogeneous mixture of clay, silt, sand, gravel, and boulders ranging widely in size and shape [6].
2451	tilted aquifer	A dipping aquifer [16].
2452	time base	The sum of storm duration time and concentration time in a hydrograph [16].
2453	time-drawdown curve	A plot of drawdown variation with time [16].
2454	time lag	The time elapsed between the onset of a certain event and the reaction to this event [16].
2455	time of concentration	The time required for surface runoff produced in the farthest part of a basin to reach a concentration point under consideration [16].
2456	time of rise	The time between the first arrival of runoff and arrival of the peak flow [16].
2457	tinajita	(Spanish) See solution pan.
2458	tinticite	A cave mineral — Fe₆(PO₄)₄(OH)₆·7H₂O [11].
2459	toadstone	Local term in the Peak District, England for lavas, tuffs and igneous intrusions within the local Carboniferous carbonate sequence.
2460	topofil	A mechanical cave survey device that uses a roll of thread and a distance counter, a protractor to measure inclination and a compass to measure the bearing [25].
2461	topographic divide	A crest line dividing one drainage basin from another [16]. See also divide.
2462	topographic map	A map representing the land surface via the use of contour lines which are lines of equal elevation on the earth’s surface. Synonym: topo map.
2463	topography	The physical features of a geographical area [16].
2464	topsoil	The topmost portion of a soil profile [16].
2465	torca	(Spanish) Large closed depression, more or less circular; a doline [10].
2466	torricellian chamber	A submerged air-filled chamber of a cave at a pressure below atmospheric pressure, sealed by water, having an air-water surface above that of adjacent free air-water surfaces [10].
2467	tortuosity	The ratio of actual length of pore channel to over all length of sample. The sinuosity of actual flow path in a porous medium [16].
2468	total dissolved solids, TDS	1. The total concentration of dissolved constituents in solution, usually expressed in milligrams per liter [22]. 2. The total concentration of dissolved material in water [as] ordinarily determined from the weight of the dry residue remaining after evaporation of the volatile portion of an aliquot of the water sample [22].
2469	total hydraulic head	See head, total.
2470	total pore space	The sum of interconnected and noninterconnected pore space [16].
2471	total runoff	The sum of all components of runoff into a stream [16].
2472	total soil-water potential	The sum of the energy-related components of a soil-water system; i.e., the sum of the gravitational, matric, and osmotic components [22].
2473	tourelle	(French) A little tower; applied to small flat-topped buttes of limestone in karst areas. Contrasted with pitons, which have pointed tops, and with coupoles, which have rounded tops [10].
2474	tower karst, towerkarst, turmkarst	1. A spectacular variety of karst landscape dominated by steep or vertical sided limestone towers each 30–300m high. By far the most extensive and best developed tower karst is the Guangxi province of southern China. Towers originate as residual cones and are then steepened by water table undercutting from surround alluviated plains. Tectonic uplift matched by karst erosion then increases tower heights, but if uplift exceeds surface lowering the towers are raised to hillside locations and the landscape is rejuvenated to form a new generation of dolines and cone karst. Many towers are riddled with relict caves at high levels, and with active caves through their bases [9]. 2. Karst topography characterized by isolated residual limestone hills displaying numerous shapes (e.g., cone shaped, steep-sided) separated by areas of alluvium or other detrital sand; towers are generally forest-covered hills, and many have flat tops. They may form as isolated hills or in groups. 3. A type of karst topography, common in the tropics, in which the residual hills rise in steep-sided but flat-topped mounds (resembling towers) from intervening depressions or dolinas (sinkholes) [20]. Synonyms: (French) karst à tourelles, karst à tours; (German) Turmkarst, Kegelkarst; (Italian) carsismo con forme residuali a torre; (Spanish) karst de torres; (Turkish) kuleli karst. See also cone karst; cupola karst; pinnacle karst; fengcong; fenglin.
2475	trace	A short length of wire with fasteners used for attaching ladders and ropes to an anchor [25].
2476	tracers	Materials, such as chemicals, dyes, radioactive salts, and light insoluble solids introduced into underground waters to determine points of egress of the water and its velocity [10].
2477	tracer-flow method	A method of determining flow velocities and directions by introducing tracers or indicators into ground water [16].
2478	tracer gaging	Determining stream discharge by inserting a known quantity of dye and measuring its concentration after mixing [25]. Consists of either the tracer-dilution method or the tracer- velocity method (salt-velocity method). Synonym: dye gaging.
2479	traction load	See bed load.
2480	tranquil flow	Open channel flow with Froude number smaller than unity [16].
2481	transgression	The spreading of the sea over level areas [16].
2482	transient	A pulse dampened oscillation or other temporary phenomena occurring in a system prior to reaching a steady-state condition [22]. See flow, unsteady.
2483	transition zone	1. Portion of bedrock in the vadose zone that is between the epikarst zone and the phreatic zone, is relatively waterless and unfractured, but is locally breached by discrete percolation points (vadose shafts.) 2. The zone in which the properties of two adjacent units change gradually (freshwater/saltwater). See also epikarst zone; subcutaneous drain; subcutaneous flow; subcutaneous zone; vadose caves; vadose shafts.
2484	transit time; travel time	The travel time of a sonic impulse through a given length of rock [16].
2485	transmission capacity	The property of a porous medium to conduct fluid [16].
2486	transmissibility coefficient	The use of the term transmissibility has been replaced by transmissivity [22]. See transmissivity.
2487	transmissivity	The rate at which water of the prevailing kinematic viscosity is transmitted through a unit width of an aquifer under a unit hydraulic gradient [6]. Though spoken of as a property of the aquifer, it embodies the saturated thickness and the properties of the contained liquid as well. It is equal to an integration of the hydraulic conductivities across the saturated part of the aquifer perpendicular to the flow paths [22].
2488	transpiration	The process by which water absorbed by plants, usually through the roots, is evaporated into the atmosphere from the plant surface [6].
2489	transpiration depth	The depth of water consumed annually by plants [16].
2490	transpiration ratio	The ratio of water weight transpired to weight of dry matter produced [16].
2491	transport	Conveyance of solutes and particulates in flow systems. See also solute transport; particulate transport [22].
2492	transportational process	All processes contributing to the transport of eroded material [16].
2493	transverse permeability	See permeability, transverse.
2494	transverse wave	A wave generated by shearing displacement where wave motion is perpendicular to direction of propagation [16].
2495	trap	See siphon; sump; water trap.
2496	traverse	1. The commonest form of cave survey in which direction, distance and vertical angle between successive points are measured. 2. A way along ledges above the floor of a cave. 3. To move along such a way [25].
2497	travertine	1. Hard calcareous mineral deposited by flowing water, that is the same as the calcareous variety of sinter and comparable to the softer tufa. The term is normally used only for deposits formed outside caves, where plants and algae cause the precipitation by extracting carbon dioxide from the water and give travertine its porous structure. Travertine forms most commonly on waterfalls that build up like gour dams. Famous examples include those at Plitvice in Croatia, Dunn’s River Falls in Jamaica, and, largest of all, Band-I-Amir in Afghanistan [9]. 2. Calcium carbonate, CaCO₃, light in color and generally concretionary and compact, deposited from solution in ground and surface waters. Extremely porous or cellular varieties are known as calcareous tufa, calcareous sinter, or spring deposit. Compact banded varieties, capable of taking a polish, are called onyx marble or cave onyx [10]. 3. Generally compact calcium carbonate rock formed by precipitation of soluble bicarbonates when equilibrium is lost due to changes in temperature and chemical characteristics. Soft, porous variety is called calcareous tufa [20]. Synonyms: (French) travertin; (German) Kalktuff, Sinter, Travertin; (Greek) travertinis/asvestolithikos toffos; (Italian) travertino; (Russian) travertin; (Spanish) travertino, toba; (Turkish) traverten, sutaşı; (Yugoslavian) sedra, travertin, bigar, lehnjak. Related to sinter and tufa.
2498	travertine terraces	Terraces and related forms covered or composed of carbonates precipitated from water. Such precipitation is usually from saturated bicarbonate waters (as from karst) when they enter a zone of turbulent flow [20]. Synonyms: (French) terrasse de travertin; (German) Travertin-Terraße; (Greek) anavathmos travertinou; (Italian) spianata di travertino; (Spanish) terrazas travertínicas; (Turkish) sutaşı traçaları; (Yugoslavian) slapovi. See also constructive waterfall.
2499	trellis	A geometrical arrangement of an interwoven pattern [16].
2500	trellis drainage pattern	A arrangement of stream and tributaries in a rectangular fashion [16].
2501	tributary	A stream contributing its waters to another stream of higher order [16].
2502	tributary river	A smaller stream entering and contributing to the flow of a larger river [16].
2503	tributary valley	A less important valley joining a larger valley [16].
2504	tri-cam	A metallic device placed in holes or cracks for use as an anchor [25]. Compare chock
2505	triple point	A point at which the solid, liquid, and vapor phases are in equilibrium [16].
2506	tripoly	A very fine grained silica sand [16].
2507	tritium	A short-lived isotope of hydrogen (λ = 12.43 y) that is directly incorporated into the water molecule as ¹H³HO or ¹HTO [24]. Commonly used for tracing ground water and for age dating of ground water [16]. See also radioisotope; radioactive tracer; tracers.
2508	Trittkarren	(German) These are best described as heel-print karren because they resemble the imprint of a heel. They are nearly connected with subhorizontal, adjacent, flat plains and migrate upslope by cutting “steps” through the process of retrogressive corrosion. The semi-circular form is preserved by the “horseshoe falls effect” which concentrates the main amount of water on the innermost part of the heel-print. At the upper rim the water gain speed. The thickness of the film of water is indirectly proportional to the speed of the flow. A higher rate of flow results in a greater effectiveness of fresh precipitation added to the flow on the ground, but it also causes the diffusion of atmospheric CO₂ and more extensive corrosion. Most Trittkarren originate at the rim of a grike lying below and have moved upward to the surface through retrogressive corrosion. At the base of steep slopes where snow collects, nearly funnel-shaped Trittkarren appear and are of subnival origin. They are common in the Alps [3]. Synonym: heel-print karren.
2509	trough	A depression usually on the land surface, but can be found to occur in ground water.
2510	troglobite	1. An animal living permanently underground in the dark zone of caves and only accidentally leaving it [10]. 2. A creature that is fully adapted to life in total darkness and can only complete its life cycle underground [13]. 3. A creature that lives permanently underground beyond the daylight zone of a cave. Many troglobitic species are adapted in some way to living in a totally dark environment. Synonyms: (French) troglobie; (German) Troglobiont; (Greek) troglothitis; (Italian) troglobio; (Russian) troglobiont; (Spanish) troglobio; (Turkish) troglobit, kör balık.
2511	troglodyte	A human cave-dweller [10]. Examples would be early “cave man”.
2512	troglomorphy	The physical characteristics of a troglobite or stygobite; e.g., reduced eyes and pigment, elongated appendages, well-developed tactile and olfactory organs, etc [23].
2513	troglophile	1. “Cave lover.” An animal that can complete its life cycle in caves, but may also do so in suitable habitats outside caves [23].
2514	troglophobe	An animal or person unable physically or psychologically to enter the dark zone of a cave or other underground area [10].
2515	trogloxene	1. “Cave visitor.” An animal that habitually enters caves, but must return periodically to the surface for certain of its living requirements, usually food [23].
2516	trophic levels	Feeding levels in a food chain, such as producers, herbivores, and so on. Most food chains include a maximum of four or five trophic levels [23].
2517	true velocity	Ground-water flow velocity in porous interstice or cavernous opening [16].
2518	True North	The direction of the geographical north pole at a place [25].
2519	truncation	A horizontal or vertical clean cut through a topographic feature [16].
2520	tsingi	Type of pinnacle karst found on limestone in Madagascar [9].
2521	tube, lava	See lava cave.
2522	tubular passage; tube; tube passage	1. Cave passage formed by approximately equal dissolution all round when full of flowing water within the phreas. Relict tubes, abandoned as the water table was lowered, are common in old caves, and may be partially filled by sediment, breakdown or stalagmite, or entrenched to form keyhole passages. Tube sizes range to over 15m in diameter, but the larger ones are rarely of uniform section. Peak Cavern in Derbyshire is well known for its fine circular phreatic tubes. Some of the trunk passages of Mammoth Cave, Kentucky, are spectacular tubes of elliptical section, formed by dissolution rates that were higher along the bedding than across [9]. 2. These are nearly horizontal cave passages (tunnels) with round or elliptical cross sections and are either straight or winding. At Mammoth Cave they vary in size up to 30 feet high and nearly 100 feet wide. They are formed while completely filled with flowing water. Whereas they are typically wider than high as a result of dissolution along horizontal cracks and bedding-plane partings, they may also form as high, narrow, straight fissures along major vertical or near vertical fractures [15]. See also canyon passage; keyhole passage; passage; vertical shaft.
2523	tubular spring	See spring, tubular.
2524	tufa	Soft, porous concretions of carbonate reprecipitated from saturated karst water, often around plants [22]. See also sinter; travertine.
2525	tunnel	See natural tunnel.
2526	turanite	A cave mineral — Cu₅(VO₄)₂(OH)₄ [11].
2527	turbidity	A diminishing of light penetration through a water sample due to suspended and colloidal materials.
2528	turbulence	An irregular motion of fluid particles in an inertia dominated flow regimen [16].
2529	turbulent flow	1. Type of flow that begins to develop in a dissolutional sub-conduit as its diameter increases to the point where differences between flow velocity at the bounding wall (slowed due to friction and adhesion) and the maximum velocity in the tube’s center are sufficient to cause development of eddies within the flowing water [9]. 2. The flow condition in which inertial forces predominate over viscous forces and in which head loss is not linearly related to velocity [22]. It is typical of flow in surface-water bodies and subsurface conduits in karst terranes provided that the conduits have a minimum diameter of approximately 2–5mm although some research has suggested that 5–15 mm may be more appropriate. See also laminar flow; Reynolds Number; turbulent threshold.
2530	turbulent threshold	The limiting value of sub-conduit size, below which water flow is essentially laminar and above which water flow includes a significant turbulent component. Sub-conduit diameters between 5mm and 15mm have been suggested as the minimum for turbulent flow, but the value depends upon a variety of factors, including the flow velocity; at low flow velocities laminar flow conditions may persist in tubes up to 500mm in diameter [9]. See also laminar flow; Reynolds Number; turbulent flow.
2531	turlough	(Irish) 1. A karst depression that may be dry or flooded according to season or prevailing weather conditions; derived from the Irish term for “dry lake”. Oscillations in the general ground-water level, including variations in response to local or more distant tidal effects are the probable mechanism for water level changes in the true turloughs. Effects that appear similar can be produced by high surface runoff into a closed depression with only restricted capacity for the drainage to sink underground [9]. 2. A depression in limestone or in glacial drift over limestone that is liable to flood either from excess surface runoff or from rising ground water. From the Irish words tuar loch, meaning dry lake [10].
2532	Turmkarst	(German) See tower karst.
2533	twilight zone	The area of a cave where light penetrating through the entrance is sufficient to permit human vision [23]. See also zonation.
2534	type curve	A plot of the theoretical well function verses the lower limit of the integral in Theis’ graphical solution method [16]. Numerous variations of Theis’ original work have been developed for which type curves readily exist.
2535	tyuyamunite	A cave mineral — Ca(UO₂)₂(VO₄)₂·nH₂O [11].
2536	unaltered rock	Rock that has not experienced physical or chemical erosion [16].
2537	unconfined	A condition in which the upper surface of the zone of saturation forms a water table under atmospheric pressure [22].
2538	unconfined aquifer	An aquifer where the water table is exposed to the atmosphere through openings in the overlying materials.
2539	unconfined flow	Ground-water flow displaying a free surface [16].
2540	unconfined water	Ground water vertically in direct contact with the atmosphere [16].
2541	unconformity	A fossil land surface representing the absence of a sequence of sediments [16].
2542	unconformity spring	See spring, unconformity.
2543	uncontaminated zone	In electrical logging practice, the zone around a borehole that has not become contaminated by mud filtrate [16].
2544	undercut karren	These are Rinnenkarren (solution grooves) that have been transformed by humus filling and by their side walls having been hollowed under by biogenic CO₂ [3].
2545	underflow spring	See spring, underflow.
2546	underdrainage	The drainage from under a hydrologic feature such as a river, barrier, lake, etc.
2547	underfit stream	A small stream that flows along a cave passage that was enlarged to its current size by an earlier, larger stream. Commonly underfit streams are found flowing under vadose conditions along the floors of drained phreatic tubes, long abandoned by the phreatic flow that enlarged them. Underfit streams may also occur if the major flow in a vadose streamway is captured to lower levels by the opening of a new shaft. The main flow no longer uses the downstream passages, leaving any tributaries to amalgamate as an underfit stream [9].
2548	underflow	Deep phreatic flow within an aquifer, along flow lines that are largely unrelated to the more obvious flow at higher levels. Underflow drainage may be slower than that in shallower systems, and may travel towards more distant and/or unrelated springs [9].
2549	underground divide	Subsurface watershed between two catchment areas in karst; often with incongruent with the surface topography of the area [20]. Synonyms: (French) ligne de partage des eaux souterraines, limit souterrainne; (German) unterirdische Waßerscheide; (Greek) ypoghios ythroketis; (Italian) spartiacque sotterraneo; (Russian) vodorazdel podzemnih vod; (Spanish) divisoria subterránea; (Turkish) yeraltı su bölümü; (Yugoslavian) podzemna razvodnica, podzemna vododelnica. See also subsurface divide.
2550	underground river, underground stream	Water flowing in channels through caves, caverns, and larger galleries in karst terranes [20]. Synonyms: (French) rivière souterraine; (German) Höhlenfluß, unterirdischer Fluß; (Greek) ypoghios roe, potamos; (Italian) fiume sotterraneo; (Russian) podzemnaja reka; (Spanish) río subterráneo; (Turkish) yeraltı nehri, deresi; (Yugoslavian) podzemni tok, podzemna rijka, podzemna reka. See subterranean river.
2551	underground waters	All subsurface waters [16]. Not to be confused with ground water which specifically refers to water within the phreatic zone.
2552	uniaxial (unconfined) compression	Compression caused by the application of normal stress in a single direction.
2553	uniaxial state of stress	The state of stress in which two of the three principles stresses are zero.
2554	uniform flow	Flow with constant velocity at all points and at all times [16].
2555	uniformity coefficient	A numerical expression of the variety in particle sizes in mixed natural soils, defined as the ratio of the sieve size on which 40% (by weight) of the material is retained to the sieve size on which 90% of the material is retained [6].
2556	unit-hydrograph	A hypothetical discharge hydrograph for a given point resulting from unit rainfall which produces unit runoff [16].
2557	unsaturated coefficient of permeability	The apparent coefficient of permeability in flow through an unsaturated medium [16].
2558	unsaturated flow	1. The movement of water in a porous medium in which the pore spaces are not filled to capacity with water [22]. 2. Two phase flow through pores only partially filled with water and air [16].
2559	unsaturated zone	See vadose zone and zone of aeration.
2560	unsteady flow	Flow with a finite local acceleration term and streamlines that vary with time [16].
2561	unterirdische karst	See interstratal karst.
2562	upconing	Process by which saline water underlying freshwater in an aquifer rises upward into the freshwater zone as a result of pumping water from the freshwater zone [22].
2563	uplift	1. The hydrostatic force of water exerted on or underneath a structure tending to cause a displacement of the structure. 2. The relative upward movement of a part of the earth’s crust [16].
2564	upper confining bed	An impermeable bed overlying an aquifer [16].
2565	upside-down channel	See ceiling channel.
2566	urkarst	See buried karst.
2567	uvala	1. A multi-coned closed depression; now little-used term of Croat, Serb or Bulgarian origin. The term was introduced to describe features assumed to be the second step in a 3-stage process of polje development, in which dolines were supposed to coalesce into uvalas. This mechanism is no longer accepted and the term uvala has fallen into disuse [9]. 2. Large closed depression formed by the coalescence of several dolines which have enlarged towards each other. Typically, the floor is irregular, being a combination of doline floors and degraded slopes of the individual hollows [19]. 3. A Yugoslavian term for an elongated closed depression in karst that is commonly dry or with periodical small sinking streams or inundations. They are generally a few hundred meters long and may be considered as a small polje [20]. Synonyms: (American) compound doline; (French) cuvala; (German) Uvala; (Greek) ouvala; (Italian) avvalamento carsico, uvala; (Russian) uvala; (Spanish) uvala; (Turkish) koyak; kokurdan; (Yugoslavian) draga. See also canyon; karst valley; valley sink. Related to polje.
2568	vadose cave	1. A cave that underwent most of its development above the water table. Within the vadose zone, drainage is free-flowing under gravity, and cave passages therefore have air above any water surface. The gravitational control of vadose flow means that all vadose cave passages drain downslope, they exist in the upper part of a karst aquifer, and they ultimately drain into the phreatic zone or out to the surface. Active stream caves, explorable by non-diving cavers, are by definition vadose (though they generally have phreatic origins). Characteristics of vadose caves are uneroded ceilings (except for immature phreatic features pre-dating the vadose conditions) and continuous downhill gradients (unless interrupted by short perched sumps). The main passage forms are canyons, with meanders and potholes, broken by sub-cylindrical, spray- corroded shafts that may demonstrate waterfall retreat. Some of the caves of Monte Canin, Italy, are spectacularly long and deep vadose systems [9]. 2. Older, higher cave passages found in the vadose zone; usually vadose caves have been abandoned by the ground water except in times of extreme aquifer recharge. Passages are usually appear as canyons and keyholes.
2569	vadose flow	Water flowing in free-surface streams in caves [25].
2570	vadose seepage	See percolation, percolation water.
2571	vadose shaft	A vertical tube in the vadose zone that may be a few inches to several feet in diameter and may be a few feet deep to hundreds and over a thousand of feet deep. They commonly occur as complexes. A drain hole is usually evident at their base. See also vertical shaft.
2572	vadose water	1. That part of the underground water in a karst limestone which circulates freely under gravity above the level of saturation - the vadose zone. Caves formed by flowing water are said to be vadose caves [19]. 2. Water in the zone of aeration; water above the zone of saturation [10].
2573	vadose zone	1. The zone between the land surface and the water table [22]. 2. The zone between the land surface and the deepest water table which includes the capillary fringe. Generally, water in this zone is under less than atmospheric pressure, and some of the voids may contain air or other gases at atmospheric pressure. Beneath flooded areas or in perched water bodies the water pressure locally may be greater than atmospheric [22]. When discussing a karst setting, it is preferable to use the term, vadose zone, so as to avoid confusion regarding chemical saturation. Synonym: unsaturated zone. See also zone of aeration.
2574	valley fill	Unconsolidated debris accumulated on a valley bottom [16].
2575	valley sink	(American) An elongated closed depression or series of interconnecting depressions forming a valley-like depression. Compare karst valley; uvala [10].
2576	valley spring	See spring, valley.
2577	vanadinite	A cave mineral — Pb₅(VO₄)₃Cl [11].
2578	vaporization	The process by which liquid or solid water changes into the gaseous state [16].
2579	variable-temperature zone	The area of a cave where air temperature fluctuates with the seasons. See also zonation.
2580	variance	The square of the standard deviation [16].
2581	variscite	A cave mineral — AlPO₄·2H₂O [11].
2582	varve	The alternating of coarse and fine grained layers in glacial lake sediments [16].
2583	vasque	A large, shallow solution pan formed in the intertidal zone of warm seas by the action of brine and marine organisms [19].
2584	vauclusian spring; vauclusian rising	See spring, vauclusian.
2585	vegetation cover	The cover living vegetation on top of the upper soil horizon [16].
2586	vein	A mineral filled fracture cutting through a host rock. The mineral filling may be derived from the host rock, as is the case with many calcite veins in limestone (e.g. at Marble Showers in Ogof Ffynnon Ddu) or derived from other, generally deeper, sources, such as the many veins containing lead and zinc ore minerals in the Derbyshire Peak District, England [9].
2587	velocity, average interstitial	The average rate of ground-water flow in interstices expressed as the product of hydraulic conductivity and hydraulic gradient divided by the effective porosity. Synonymous with average linear ground-water velocity or effective velocity.
2588	vermiculation	Pattern of thin, worm-shaped coatings of clay or silt on cave surfaces [25].
2589	vertebrate	An animal with a backbone. The group includes fishes, amphibians, reptiles, birds, and mammals. Some amphibians and fishes live permanently in caves. See also invertebrate.
2590	vertical angle	The angle in a vertical plane between a line of sight and the horizontal, positive above the horizontal and negative below [25].
2591	vertical cave	A vertical passage within a cave system, formed along joints by which underground watercourses are transferred from a higher to a lower bedding plane [19]. They may become transformed into vertical shafts by sufficiently uniform dissolution as to create a rounded vertical passage. See also fissure cave; vertical shaft.
2592	vertical shaft	These are formed by underground water dripping of flowing straight downward through the limestone along vertical cracks. Uniformly distributed dissolution of the rock results in a silo- or well-shaped passage so that most of them appear roughly circular in cross section when viewed straight up and down. They form above active tubular passages although they may intersect a limited number of passages along their length. At Mammoth Cave, they range in size from 30 feet across to 200 feet from top to bottom [15]. Synonym: dome-pit. See also canyon passage; fissure cave; keyhole passage; passage; tubular passage; vadose shaft; vertical cave.
2593	vertical caver	A caver who enjoys and is competent doing vertical caving [13]. See also vertical caving.
2594	vertical caving	Caving that includes a lot of ascending and descending [13]. See also vertical caver.
2595	very fine sand	Grain particles with diameters ranging from 0.05 to 0.1 mm [16].
2596	vesicular	Containing small circular cavities [16].
2597	victor tube	The single phreatic sub-conduit among the many that potentially exist on a given bedding plane (or fracture plane) that is the first to reach a diameter capable of establishing turbulent-flow conditions. Following this breakthrough the victor tube tends to enlarge more rapidly than other branching or sub-parallel alternatives and eventually captures much of the drainage within its field of influence [9].
2598	virgin flow	Flow unaffected by artificial diversions, impoundments, or channels [16].
2599	virgin passage	A cave passage that has not previously been entered; a new discovery [13].
2600	viscosity	1. The resistance of liquid to flow [16]. 2. The property of a real fluid creating shear forces between two fluid elements and giving rise to fluid friction [16]. Specifically, it is the ratio of the shear stress to the rate of shear strain [6].
2601	void	See interstice.
2602	void ratio	The ratio of (a) the volume of void space to (b) the volume of solid particles in a given soil mass [22].
2603	volatiles	Substances with relatively large vapor pressures. Many organic substances are almost insoluble in water so that they occur primarily in a gas phase in contact with water, even though their vapor pressure may be very small [22].
2604	volumetric flowmeter	Apparatus designed to measure a volume flow rate [16].
2605	volumetric moisture content	The concentration of water in soil by volume [16].
2606	vrulje	(Yugoslavian) See submarine spring.
2607	vug	A small cavity in rock usually lined with crystals. Adjective, vuggy [10]. See also geode.
2608	vugular pore space	Void space due to solution cavities of small size [16].
2609	vulcanokarst	An area comprised of tubular caves within lava flows and shows evidence of mechanical collapse of the roof into them. See also lava cave; pseudokarst.
2610	wading measurement	Discharge measurement during which a hydrographer takes readings while standing in a river [16].
2611	wall block	A roughly cubical joint-controlled large block of limestone or dolomite, which has rotated outward from a cave wall [10]. See also cave breakdown; wall slab.
2612	wall karren	These are found on vertical walls as a result of water flowing down the walls without any area-wide moistening although area-wide sprinkling occasionally influences their development [3]. See also meandering karren; humus-water grooves.
2613	wall pocket	See pocket.
2614	wall slab	A thin but large block of rock, which has fallen outward from the wall of a cave in limestone in which the dip is nearly vertical [10]. See also cave breakdown.
2615	wang	(Malaysian) Polje [10].
2616	wash	A small ravine due to outwash by flow in desert regions [16].
2617	wash load	The incoming load of suspended sediment passing through a river network without deposition [16].
2618	waste load	The content of wastes by weight of volume transported by or discharged into a river [16].
2619	waste water	Water containing sewage and waste products [16].
2620	water-balance	An instrument designed to measure evaporation by gravimetry [16].
2621	water-bearing	Containing water [16].
2622	water-borne disease	Disease spread by organic contaminants contained in the water supply [16].
2623	water budget	The quantitative accounting of water volumes involved in the hydrologic cycle [16].
2624	water catchment	The intake of water from an aquifer or a surface reservoir [16].
2625	water conservation	All measures to reduce the quantitative of qualitative spoilage of water [16].
2626	water content	The amount of water lost from the soil after drying it to constant weight at 105°C, expressed either as the weight of water per unit weight of dry soil or as the volume of water per unit bulk volume of soil [22]. See moisture content.
2627	water course	Any channel conveying water [16].
2628	water equivalent	The depth of water resulting from the melting of snow [16].
2629	water hammer	An abnormally high pressure rise in a pipe when sudden changes in flow occur [16].
2630	water-holding capacity	See specific retention.
2631	water invasion	The sudden invasion of water into a well or borehole [16].
2632	water level	The level of free surface of a water body or water column [16].
2633	water logged	See waterlogged.
2634	water logging	See waterlogging.
2635	water of constitution	Chemically bound water [16].
2636	water of crystallization	Water embodied in crystal structure [16].
2637	water of dehydration	Water freed from hydrous minerals by chemical changes [16].
2638	water pot	See kamenica, solution pan.
2639	water quality	The physical, chemical, and biological characteristics of water [16].
2640	water requirement	The quantity of water needed for crops regardless of the source [16].
2641	water resources	The total supply of surface, ground, and reclaimed water that can be used [16].
2642	water stage	The height of the water level [16].
2643	water table	1. The top surface of a body of slowly moving ground water that fills the pore spaces within a rock mass. Above it lies the freely draining vadose zone, and below it lies the permanently saturated phreas. In uniform aquifers, such as sandstone, the water table is a smoothly contoured surface intersecting the ground at rivers and lakes, but in limestone it is more complex. Individual cave conduits may be above or below the water table, and therefore either vadose or phreatic, and the water table cannot normally be related to them. The water table concept does, however, apply to the diffuse drainage of percolation water in the micro- fissure network of limestone, but its detailed structure may be complicated by the presence of conduits. The water-table slope (hydraulic gradient) is low in limestone due to the high permeability, and the level is controlled by outlet springs or local geological features. High flows create steeper hydraulic gradients and hence rises in the water level away from the spring. In France’s Grotte de la Luire, the water level in the cave (and therefore the local water table) fluctuates by 450m [9]. 2. The upper surface of a zone of saturation except where that surface is formed by a confining unit [22]. 3. The upper surface of the zone of saturation on which the water pressure in the porous medium equals atmospheric pressure [22]. 4. The upper boundary of an unconfined zone of saturation, along which the hydrostatic pressure is equal to the atmospheric pressure [10]. See also potentiometric surface.
2644	water-table aquifer	See unconfined aquifer.
2645	water-table cave	In theory the water table offers the prime environment for cave development as it provides the shortest route through the phreas and is potentially more active chemically due to the presence of the air/water interface. However, geological factors determine the details of cave inception and enlargement, and passages most commonly form just below the water table as a shallow phreatic variety of cave development. Development of this type is believed to be responsible for the “levels” of cave passage found in some areas, as in the flint Mammoth Cave System, Kentucky. True water-table caves are rare except on a limited scale as extensions to cliff foot notches margined to tropical swamps. Also under these conditions, the water table may adjust down to the level of a mature phreatic cave and then modify the passage with horizontal dissolution notches — as is common in the caves of Mulu and Niah, Sarawak [9].
2646	water-table divide	See divide.
2647	water-table map	A map showing the upper surface of the phreatic zone of a water-table aquifer by means of contour lines [1]. See also phreatic zone; potentiometric-surface map; water-table aquifer.
2648	water tracing	Underground drainage links through unexplored caves confirmed by labeling input water and identifying it at points downstream. The common labeling techniques involve the use of fluorescent dyes (fluorescein, rhodamine, leucophor, pyranine etc.), lycopodium spores, or chemicals such as common salt. Detection of dye downstream may be purely visual, but if the dye is used at a subvisible (environmentally acceptable) dilution, suitable detectors must be placed in all potential risings and collected for subsequent fluorometric examination (although water samples are more desirable and beneficial). Lycopodium spores are usually collected in fine nets, along with other stream-borne sediment, and must then be identified under the microscope. If chemical tracers are used, regular water samples must be collected for subsequent analysis, or the resurgent waters must be monitored with suitable electronic detectors and recorders. Flowpaths can also be confirmed by transmission of artificial or natural flood pulses, which provide additional data on the nature of conduits, as a pulse is transmitted instantaneously through flooded passages. The longest successful water trace was from Beysehir Golu to the Manavgat springs, in Turkey, over a distance of 130km; 390kg of fluorescein was used and the dye reappeared after 366 days [9].
2649	water trap, watertrap	A place where the roof of a chamber or passage of a cave dips under water but lifts again farther on [10]. Synonym: trap.
2650	water works	A plant where water is treated and prepared for municipal consumption [16].
2651	water year	A 12 month period for streamflow computation [16].
2652	waterlogged	Water saturated [16].
2653	waterlogging	Water accumulation on top of soil where the water table and ground surface coincide [16].
2654	watershed	1. A drainage basin [16]. 2. A divide separating one drainage basin from another [16].
2655	waterway	An artificial or natural watercourse fit for navigation.
2656	wave karren	Wavy karren surfaces that appear similar to corrugated tin. When denuded they are a disposition for the formation of Rinnenkarren [3]. See also covered karren; Rinnenkarren; root karren.
2657	wayboard	One of many thin beds of volcanic clay that occur at intervals within the Carboniferous carbonate succession of the Peak District, England; a term formerly used by lead miners (see toadstone). Wayboards have potential significance during speleogenesis when they may act as local aquicludes, inception horizons or providers of strong acid formed by oxidation of sulfide minerals [9].
2658	weathering	The process of disintegration and decomposition as a consequence of exposure to the atmosphere, to chemical action and to the action of frost, water and heat.
2659	wedge storage	1. Water storage in the form of a wedge overlying a prism [16]. 2. storage in a flooded river segment [16].
2660	weir	A dam across a water course to control, raise, or measure water flow [16].
2661	weir coefficient	A coefficient used in transforming water depths into discharge volumes in weir measurements [16].
2662	well	1. A shaft or hole sunk into the earth to obtain water, oil, gas, or minerals [10]. 2. A deep vertical rounded hole or shaft in the floor of a cave or at the bottom of a closed depression [10]. 3. A bored, drilled or driven shaft, or a dug hole, whose depth is greater than the largest surface dimension [22].
2663	well function	An exponential integral as used in Theis’ nonequilibrium equation [16].
2664	well hydrograph	A graph of water level fluctuations in a well [16].
2665	well loss	Head loss caused by flow through a screen and inside a well [16].
2666	well-sorted grains	An assortment of grains having the same diameter [16].
2667	well yield	The volume of water discharged from a well in gallons per minute or cubic meters per day.
2668	wet line	That portion of line of submerged under water in stream measurements [16].
2669	wet suit	A diving garment of foam neoprene designed to insulate the diver from the cold but which allows a thin film of water to penetrate between the suit and the body [25].
2670	wetland	A general term used for a group of wet habitats, in common use by specialists in wildlife management. It includes areas that are permanently wet and/or intermittently water-covered, especially coastal marshes, tidal swamps and flats, and associated pools, sloughs, and bayous [1].
2671	wettability	The property of a solid substance to be wetted by a liquid such as water [16].
2672	wetted area	The cross sectional area of that portion of a channel that is filled with water [16].
2673	wetted perimeter	The perimeter over which flowing water is in actual contact with the channel walls and bottom [16].
2674	wetting period	The period of contact between a liquid and a solid surface during which wetting occurs [16].
2675	whaletail	A descender consisting of an aluminium block with slots, knobs and a safety gate [25].
2676	whitlockite	A cave mineral — Ca₉(Mg,Fe)H(PO₄)₇ [11].
2677	width of contribution	The width of the contributing region between the ground-water divide from which water enters a well. This usually occurs with an inclined piezometric surface [16].
2678	wilt, to	The shrinking of cell walls due to loss in turgor as a result of water deficiency in the plant [16].
2679	wilting coefficient, wilting point	The soil moisture content at which plants wilt [16].
2680	wind factor	The factor containing a monthly mean wind velocity in evaporation [16].
2681	wind field	The air velocity field above ground due to wind action [16].
2682	window	1. In speleology, a natural opening above the floor of a passage or a room, giving access to an adjoining cavity or to the surface; larger and less symmetrical than a porthole. 2. The opening under the arch of a small natural bridge [10]. See karst window.
2683	windypit	Open fissure, widened by landslip, common in valley side situations where limestone overlies weaker rocks such as clays or shales. The term is commonly used to describe gulls and tectonic caves in the Jurassic limestones of north-east Yorkshire, England [9].
2684	withdraw, to	To draw water from an aquifer or reservoir [16].
2685	workover	The reworking of a well that has declined in yield [16].
2686	yield	The quantity of water discharged from an aquifer [16] (e.g spring or well.) See also well yield.
2687	zadernovannyĭ karst	(Russian) See subsoil karst.
2688	zakrytyĭ karst, skrytyĭ karst	(Russian) See closed karst.
2689	zanjón	(Spanish) In Puerto Rico, solution trench in limestone. Zanjónes range from a few centimeters to about 8 meters in width and from about 1 to 4 meters in depth. Apparently they form by the widening and deepening of joints by solution [10]. See also bogaz; corridor; struga.
2690	zero adjustment	The adjustment of a scale or a measuring circuit to an original point of departure [16].
2691	zonal soil profile	The normal horizontal distribution of soil zone [16].
2692	zonation	The organization of a habitat into a more or less orderly series of distinctive plant and animal associations as a result of variations in environmental conditions. Zones in a cave are the twilight zone, the variable-temperature zone, and the constant-temperature zone [23].
2693	zone of accumulation	The second horizon of a soil profile (B), usually the zone of clay accumulation subjacent to zone (A) [16].
2694	zone of aeration	The zone in permeable soil or rock that is above the zone saturated with water; the zone of vadose water [10]. See also vadose zone.
2695	zone of investigation	The zone over which a given measuring device is able to obtain information [16].
2696	zone of leaching	The top horizon of a soil profile (A) that is most intensely weathered [16].
2697	zone of saturation	The zone in permeable soil or rock that is saturated with water; the phreatic zone [10]. See also phreatic zone.
2698	zones of karstification	Cvijič (1926, 1960) distinguishes three zones of karstification: (1) dry zone in the upper part of the karst with caves almost completely dry; (2) transition zone where water flows downstream almost permanently; and (3) deep zone with slow downstream flow and local siphons [20]. Synonyms: (French) zones de karstification; (German) Zone der Verkarstung; (Greek) zoni karstikopiiseos; (Italian) zone idrogeologiche; (Spanish) zona de karstificación; (Turkish) karstlaşma kuşagı; (Yugoslavian) zone karstifikacije.
2699	Zwischenhöhle	(German) Cave in which a river passage, or former river passage, is entered from above or laterally and which can be followed upstream and downstream some distance but not to daylight [10].

References

As extracted from Field's 2002 2nd Edition Lexicon.

1. Bates, R. L. and J. A. Jackson. 1980. Glossary of Geology. American Geological Institute. Falls
Church, Va. 751 pp.

2. Bear, J. 1979. Hydraulics of Groundwater. McGraw-Hill Inc. New York, NY. 569 pp.

3. Bögli, A. 1980. Karst Hydrology and Physical Speleology. Springer-Verlag. Berlin, West
Germany. 284 pp.

4. Daoxian, Y. 1985. New Observations on Tower Karst. Paper presented at the 1st International
Conference on Geomorphology (Manchester, England). 14 pp.

5. Dreybrodt, W. 1988. Processes in Karst Systems: Physics, Chemistry, and Geology. 
Springer-Verlag. New York, N.Y. 288 pp.

6. Driscoll, F. G. 1986. Groundwater and Wells. Johnson Division. St. Paul, Minn. 1089 pp.

7. Ford, D. C. and P. W. Williams. 1989. Karst Geomorphology and Hydrology. Unwin Hyman Inc.
Lakeland, Fla. 601 pp.

8. Jennings, J. N. 1985. Karst Geomorphology. Basil Blackwell Inc. New York, N.Y. 293 pp.

9. Lowe, D. and T. Waltham. 1995. A Dictionary of Karst and Caves: A Brief Guide to the
Terminology and Concepts of Cave and Karst Science. Cave Studies Series Number 6. British
Cave Research Association. London, Britain. 41 pp.

10. Monroe, W. H. (Compiler). 1970. A Glossary of Karst Terminology. Geological Survey 
Water-Supply Paper 1899-K. U.S. Geological Survey. U.S. Government Printing Office. Washington,
D.C. 26 pp.

11. Moore, G. W. and G. N. Sullivan. 1978. Speleology: The Study of Caves. Cave Books. 2nd
Edition. St. Louis, Missouri. 150 pp.

12. Mylroie, J. E. 1984. Hydrologic classification of caves and karst. Groundwater as a Geomorphic
Agent. R. G. LaFleur, Editor. Allen & Unwin. Inc. Boston, Mass. pp. 157-172.

13. NSS. 1982. Glossary of caving terms used in this manual. Caving Basics. J. Hassemer, Editor.
National Speleological Society. Huntsville, Ala. pp. 124-125.

14. Palmer, A. N. 1972. Dynamics of a sinking stream system: Onesquethaw Cave, New York.
National Speleological Society Bulletin. 34. pp. 89-110.

15. Palmer, A. N. 1981. A Geological Guide to Mammoth Cave National Park. Zephyrus Press.
Teaneck, N.J. 196 pp.

16. Pfannkuch, H. O. 1971. Elsevier’s Dictionary of Hydrogeology. American Elsevier Publishing
Company. Inc. New York, N.Y. 168 pp.

17. Quinlan, J. F. 1978. Types of Karst with Emphasis on Cover Beds in their Classification and
Development. Unpublished Ph.D. Dissertation. The University of Texas at Austin. 323 pp.

18. Quinlan, J. F., P. L. Smart, G. M. Schindel, E. C. Alexander, A. J. Edwards, and A. Richard
Smith. 1991. Recommended administrative/regulatory definition of karst aquifer, principles for
classification of carbonate aquifers, practical evaluation of vulnerability of karst aquifers, and
determination of optimum sampling frequency at springs. Hydrology. Ecology. Monitoring. and
Management of Ground Water in Karst Terranes Conference (3rd. Nashville. Tenn. 1991). J. F.
Quinlan and A. Stanley, Editors. National Ground Water Association. Dublin, Ohio. pp.
573-635.

19. Sweeting, M. M. 1973. Karst Landforms. Selected Glossary. Compiled by K. Addison.
Columbia University Press. New York, N.Y. 362 pp.

20. UNESCO. 1972. Glossary and Multilingual Equivalents of Karst Terms. United Nations
Educational. Scientific. and Cultural Organization. Paris, France. 72 pp.

21. UNESCO. 1984. Guidebook to Studies of Land Subsidence due to Ground-Water withdrawal.
Prepared for the International Hydrological Programme. Working Group 8.4. J. F. Poland,
Editor. United Nations Education. Scientific and Cultural Organization. Paris, France. 305 pp.
(plus appendices).

22. USGS. (date ?). Federal Glossary of Selected Terms: Subsurface-Water Flow and Solute
Transport. Prepared by the Subsurface-Water Glossary Working Group. Ground-Water
Subcommittee. Interagency Advisory Committee on Water Data. Dept. of the Interior. U.S.
Geological Survey. Office of Water Data Coordination. 38 pp.

23. William R. Elliott, Ph.D. of the Natural History Division of the Missouri Department of
Conservation. The list of definitions were obtained directly from the Biospeleology web site:
www.utexas.edu/depts/tnhc/.www/biospeleology
which is based on The Life of the Cave by Charles E. Mohr and Thomas L. Poulson (1966,
McGraw-Hill) with additions from Dr. Elliott.
[GP: The above web link is no longer available. Dr. Elliott's subset of definitions is currently 
available at Pages 35-37 of 
http://www.mospeleo.org/sites/default/files/Attachements/A%20Guide%20to%20Missouri%20Cave%20Life.pdf. ]

24. Clark, I. and P. Fritz. 1997. Environmental Isotopes in Hydrology. Lewis Publishers, Boca
Raton, Fla. p. 174.

25. Australian Speleological Federation. 1996. Cave and Karst Terminology.
The list of definitions were obtained directly from the Western Australia Speleology web site:
http://wasg.iinet.net.au/terminol.html which contains a listing of terminology commonly used in Australia.
[GP: Updated address https://wasg.org.au/index.php/specialties/terminologies/karst-terminology ]

The Introduction to Field's Published Lexicon

As extracted from Field's 2002, 2nd Edition, Lexicon:

United States Environmental Protection Agency
Office of Research and Development Washington, D.C. 20460
EPA/600/R-02/003 February 2002
https://www.epa.gov/ncea

Research and Development

A Lexicon of Cave and Karst Terminology with Special Reference to Environmental Karst Hydrology

(Supercedes EPA/600/R-99/006, 1/’99)

National Center for Environmental Assessment-Washington Office
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC 20460

DISCLAIMER

This document has been reviewed in accordance with U.S. Environmental
Protection Agency policy and approved for publication. Mention of trade
names or commercial products does not constitute endorsement or recommendation
for use.

CONTENTS

PREFACE TO THE SECOND EDITION
PREFACE TO THE FIRST EDITION
AUTHOR AND REVIEWERS
INTRODUCTION
GLOSSARY
REFERENCES

PREFACE TO THE SECOND EDITION

Release of the first edition of this lexicon was well received and resulted in
two printings. The first edition is again in short supply, but rather than
going through a third printing, an updated edition was deemed appropriate.
Since the release of the first edition, additional definitions related to
biospeleology, courtesy of Dr. William R. Elliott of the Natural History
Division of the Missouri Department of Conservation, have been added.
Additional definitions obtained from the Australian Speleological Federation
also have been added.

Researchers and the general public alike will find these additions useful as
they work their way through the published literature. For this second edition,
the literature search is current to 2002. To be sure, this updated lexicon is
far from complete and will more than likely be updated in a few years.

PREFACE TO THE FIRST EDITION

The National Center for Environmental Assessment-Washington Office (NCEA-W) has
prepared this document for the benefit of the regional offices and public in
general due to the need to understand the terminology common to the field of
karst. It is a glossary of most terms that have some relationship to the field
of environmental karst as well as specific karst terms. It includes many
foreign terms because much of the karst research is conducted in foreign
countries and published using local terminology. In many instances, common
environmental terms are defined in such a way as to specifically reference
karstic phenomena.

The purpose of this document is to serve as a technical guide to regional
offices and the public in general who must read the karst literature or who
must hold discussions with karst researchers. It is intended that this document
remove much of the confusion surrounding many of the karst terms.

The literature search supporting this lexicon is current to 1998.

AUTHOR AND REVIEWERS

The National Center for Environmental Assessment-Washington Office within the
Office of Research and Development was responsible for the preparation of this
document and provided overall direction and coordination during the production
effort.

AUTHOR/COMPILER

Malcolm S. Field, Ph.D.
U.S. Environmental Protection Agency
National Center for Environmental Assessment-Washington Office
Washington, DC

REVIEWERS

Stephen R. Kraemer, Ph.D.
U.S. Environmental Protection Agency
National Exposure Research Laboratory
Ecosystems Research Division
Athens, GA

Arthur N. Palmer, Ph.D.
Department of Earth Sciences
State University of New York
Oneonta, NY

INTRODUCTION

Several attempts to classify karst terminology in an organized manner have been
attempted in the past. The last few glossaries of karst terminology were
organized in the late 1960s and published in the early 1970s. Since that time,
many new terms related to karst in general have come into use throughout the
world while other older karst terms are seldom used nowadays. In the mid 1990s
the British Cave Research Association (BCRA) published and updated a dictionary
that covers the general area of karst and caves, but did not focus on
environmental issues.

Many of the more recent karst terms are related to the upsurge in
environmentalism and the recognition among karst cognoscenti that karst
terranes are much more sensitive to man-induced effects on the environment than
are other types of landscapes. In an attempt to be as broad as possible in this
glossary, terms related to general hydrology and hydrogeology, common karst
rock and mineral types, and many of the descriptive terms used in speleology
even where they relate to specific localities, have been included. No attempt
was made to exclude foreign karst terms although many are no doubt, missing.
This has led to a much larger manuscript than was originally intended when this
project was initiated, but it has provided for a more comprehensive document.

Because many non-karst professionals, whether working on basic research or on
environmental problems, need to have a general working knowledge of karst
terminology, this glossary was developed to provide an up-to-date reference for
more modern definitions of karst terms both currently in usage and now defunct.
As with any undertaking of this sort, numerous omissions will be shown to be
evident. In other instances, disagreements regarding definitions will arise. In
the event that readers of this glossary find various omissions or incorrect
definitions, it would be greatly appreciated if the necessary corrections be
forwarded to the author so that the glossary may be updated in the future.

As a final note, it should be pointed out that a list of references for the
definitions are included at the back of this glossary and citations are
provided when appropriate. In many instances, duplication of definitions from
previous glossaries were employed to avoid changing the original definitions.
However, efforts were not always attempted to cite the exact source for each
definition as this would have greatly lengthened this already excessively long
manuscript; secondary citations have been provided. Exact citations would also
have resulted in confusion where several definitions were utilized in the
writing of a single clear definition for any particular term. In no instance
was it intended that the work of others be appropriated, only that this
glossary be as comprehensive and clear as possible while avoiding excessive
clutter. Also, where definitions were deemed to be incorrect or poorly worded,
alternatives have been written.

Licence

The term definitions from Field's original Lexicon, as a US Govt Agency publication, are in the Public Domain. This UIS adaptation is freely available under the Creative Commons Licence: Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0).

Contact

Peter Matthews (Project Leader). Mike Lake (Assisting).

You can get more information about the Glossary Project itself at this link.
You can participate via the Project Forum at this link.

The UIS Cave and Karst Glossary Stage 1

References

The Introduction to Field's Published Lexicon

Licence

Contact

The UIS Cave and Karst Glossary
Stage 1