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{{Short description|Topography from dissolved soluble rocks}}
{{Other uses|Karst (disambiguation)}}
{{Use dmy dates|date=October 2023}}

[[File:Zadar (HR), Krupa-Canyon -- 2022 -- 0003.jpg|thumb|Typical karst terrain of the [[Dinaric Alps]]]]
[[File:87340-Li-River (29881879337).jpg|thumb|[[Li River|Li Jiang]] fengcong ([[tower karst|cone karst]]) in [[Guilin]] as part of the [[South China Karst]]]]
[[File:Paisatge càrstic, 2.jpg|thumb|Karst formation of the [[Serra de Tramuntana]]]]
'''Karst''' ({{IPAc-en|k|ɑːr|s|t}}) is a [[topography]] formed from the dissolution of soluble [[carbonate rock]]s such as [[limestone]] and [[Dolomite (rock)|dolomite]]. It is characterized by features like [[polje]]s above and drainage systems with [[sinkhole]]s and [[cave]]s underground.<ref>{{Cite web|url=https://www.esi.utexas.edu/files/Whatiskarst.pdf|title=What is Karst?|date=May 16, 2006|access-date=25 December 2020|website=Environmental Science Institute |publisher=The University of Texas at Austin}}</ref><ref>{{cite book |editor1-last=Jackson |editor1-first=Julia A. |title=Glossary of geology. |date=1997 |publisher=American Geological Institute |location=Alexandria, Virginia |isbn=0922152349 |edition=Fourth |chapter=Karst}}</ref> There is some evidence that karst may occur in more [[weathering]]-resistant rocks such as [[quartzite]] given the right conditions.<ref>{{cite journal |last1=Doerr |first1=S. H. |title=Karst-like landforms and hydrology in quartzites of the Venezuelan Guyana shield: Pseudokarst or "real" karst? |journal=Zeitschrift für Geomorphologie |date=18 March 1999 |volume=43 |issue=1 |pages=1–17 |doi=10.1127/zfg/43/1999/1|bibcode=1999ZGm....43....1D }}</ref>

Subterranean drainage may limit surface water, with few if any rivers or lakes. In regions where the dissolved [[bedrock]] is covered (perhaps by debris) or confined by one or more superimposed non-soluble rock strata, distinctive karst features may occur only at subsurface levels and can be totally missing above ground.<ref>{{cite journal |last1=Billi |first1=Andrea |last2=De Filippis |first2=Luigi |last3=Poncia |first3=Pier Paolo |last4=Sella |first4=Pio |last5=Faccenna |first5=Claudio |display-authors=3|title=Hidden sinkholes and karst cavities in the travertine plateau of a highly-populated geothermal seismic territory (Tivoli, central Italy) |journal=Geomorphology |date=February 2016 |volume=255 |pages=63–80 |doi=10.1016/j.geomorph.2015.12.011|bibcode=2016Geomo.255...63B }}</ref>

The study of ''paleokarst'' (buried karst in the [[stratigraphic column]]) is important in [[petroleum geology]] because as much as 50% of the world's [[Oil and gas reserves and resource quantification|hydrocarbon reserves]] are hosted in [[carbonate rock]], and much of this is found in porous karst systems.<ref name="Derek2007" />

== Etymology ==
[[File:Carbonate-outcrops world.jpg|thumb|upright=1.4|Global distribution of major outcrops of carbonate rocks (mainly [[limestone]], except [[evaporite]]s)]]
The English word ''karst'' was borrowed from [[German language|German]] {{lang|de|Karst}} in the late 19th century,<ref>''Shorter Oxford English Dictionary'' 2002. Vol. 1, A–M. Oxford: Oxford University Press, p. 1481.</ref> which entered German usage much earlier,<ref>{{lang|de|[[Elmar Seebold|Seebold, Elmar]]. 1999. ''Kluge Etymologisches Wörterbuch der Deutschen Sprache''|italic=unset}}, 23rd edition. Berlin: Walter de Gruyter, p. 429.</ref> to describe a number of geological, geomorphological, and hydrological features found within the [[Range (geographic)|range]] of the [[Dinaric Alps]], stretching from the northeastern corner of [[Italy]] above the city of [[Trieste]], across southwestern [[Slovenia]], the [[Balkan peninsula]] along the coast of the eastern [[Adriatic Sea|Adriatic]] to [[Kosovo]] and [[North Macedonia]], where the [[massif]] of the [[Šar Mountains]] begins. The karst zone is at the northwesternmost section, described in early topographical research as a [[Karst Plateau (Italy-Slovenia)|plateau]] between Italy and [[Slovenia]].

In the local [[South Slavic languages]], all variations of the word are derived from a Romanized [[Illyrian language|Illyrian]] base (yielding {{langx|la|carsus}}, {{langx|dlm|carsus}}), later [[metathesis (linguistics)|metathesized]] in Slavic from the reconstructed form {{lang|sla|*korsъ|italic=yes}} into forms such as {{langx|sl|kras}}<ref>{{cite book |author1=Jernej Pavšič |title=Geološki terminološki slovar |date=2006 |publisher=Založba ZRC |isbn=978-961-6568-84-5 |url=https://books.google.com/books?id=ZPuPIYpasCUC&q=kras+kra%C5%A1ka+kraska&pg=PA142 |page=142 |access-date=15 June 2020 |language=sl}}</ref> and {{langx|sh|krš}}, {{lang|sh|kras}},<ref>{{cite web |last1=Šegota |first1=Tomislav |title=Krš ili kras? Krš! - Geografija.hr |url=http://www.geografija.hr/teme/krs-ili-kras-krs/ |website=Geografija.hr |access-date=30 October 2018 |language=hr-HR |date=25 January 2009 |archive-url=https://web.archive.org/web/20181103131235/http://www.geografija.hr/teme/krs-ili-kras-krs/ |archive-date=3 November 2018 |url-status=dead }}</ref><ref>{{cite web |last1=Matas |first1=Mate |title=Veliki krš oko krša u jeziku - Geografija.hr |url=http://www.geografija.hr/hrvatska/veliki-krs-oko-krsa-u-jeziku/ |website=Geografija.hr |access-date=30 October 2018 |language=hr-HR |date=7 June 2004}}</ref><ref>{{cite book |last1=Roglić |first1=Josip |title=Krš Jugoslavije |date=1974 |publisher=JAZU Jugoslovenska Akademija Znanosti i Umjetnosti |location=Zagreb |page=29 |edition=Volume 9/1}}</ref><ref>{{Cite web|url=https://www.etymonline.com/search?q=karst|title=karst &#124; Search Online Etymology Dictionary|website=www.etymonline.com|access-date=Dec 31, 2019}}</ref> first attested in the 18th century, and the adjective form {{lang|sl|kraški}} in the 16th century.<ref name="Snoj">{{cite book |last1=Snoj |first1=Marko |title=Slovenski etimološki slovar |date=2003 |publisher=Modrijan |location=Ljubljana |page=318}}</ref> As a proper noun, the Slovene form {{lang|sl|Grast}} was first attested in 1177.<ref name="Bezlaj">Bezlaj, France (ed.). 1982. {{lang|sl|Etimološki slovar slovenskega jezika|italic=yes}}, vol. 2, K–O. Ljubljana: SAZU, p. 82.</ref> Modern languages preserving the non-metathesized form (with ''-ar-'') include {{langx|it|Carso}}, {{langx|de|Karst}}, and {{langx|sq|karsti}}.

Ultimately, the word is of [[Mediterranean]] origin. It has also been suggested that the word may derive from the [[Proto-Indo-European language|Proto-Indo-European]] root {{lang|ine-x-proto|karra-}} 'rock'.<ref>Gams, I., {{lang|sl|Kras v Sloveniji&nbsp;— v prostoru in casu|italic=yes}} (Karst in Slovenia in space and time), 2003, {{ISBN|961-6500-46-5}}.</ref> The name may also be connected to the [[Oronym (toponymy)|oronym]] ''Kar(u)sádios oros'' cited by [[Ptolemy]], and perhaps also to Latin {{lang|la|Carusardius}}.<ref name="Snoj" /><ref name="Bezlaj" />

== Early studies ==
[[File:Causse de Sauveterre doline.jpg|thumb|[[Doline]] in the [[causses|causse]] de Sauveterre, [[Lozère|Lozère, France]]]]
[[Johann Weikhard von Valvasor]], a pioneer of the study of karst in [[Slovenia]] and a fellow of the [[Royal Society]], London, introduced the word ''karst'' to European scholars in 1689 to describe the phenomenon of underground flows of rivers in his account of [[Lake Cerknica]].<ref>Paul Larsen, ''Scientific accounts of a vanishing lake: Janez Valvasor, Lake Cerknica and the New Philosophy'', 2003.</ref>

[[Jovan Cvijić]] greatly advanced the knowledge of karst regions to the point where he became known as the "father of karst geomorphology". Primarily discussing the karst regions of the Balkans, Cvijić's 1893 publication ''Das Karstphänomen'' describes landforms such as karren, [[doline]]s and [[polje]]s.<ref name="Derek2007">{{cite journal |last1=Ford |first1=Derek |date=2007 |title=Jovan Cvijić and the founding of karst geomorphology |journal=Environmental Geology |volume=51 |issue= 5|pages=675–684 |doi=10.1007/s00254-006-0379-x|s2cid=129378021 }}</ref> In a 1918 publication, Cvijić proposed a [[cycle of erosion|cyclical model]] for karst landscape development.<ref name="Derek2007" /><ref>{{cite journal |last1=Cvijić |first1=Jovan |date=1918 |title=Hydrographie souterraine et évolution morphologique du Karst |journal=Recueil des travaux de l'institut de géographie alpine |volume=6 |issue=4 |pages=375–426 |doi= 10.3406/rga.1918.4727|language=fr}}</ref>

Karst [[hydrology]] emerged as a discipline in the late 1950s and the early 1960s in France. Previously, the activities of cave explorers, called [[speleologist]]s, had been dismissed as more of a sport than a science and so the underground [[Solutional cave|karst caves]] and their associated watercourses were, from a scientific perspective, understudied.<ref>{{cite book |last1=Gilli |first1=Éric |last2=Mangan |first2=Christian |last3=Mudry |first3=Jacques |translator-last=Fandel |translator-first=Choél |date=2012 |title=Hydrogeology: Objectives, Methods, Applications |publisher=CRC Press |page=7 }}</ref>

== Development ==
[[File:Limestone Eocene deposit at Sinj Stari grad - Dalmatia - Croatia IMG 20210820 083857.jpg|thumb|A limestone deposit in the [[Dinaric Alps]] near [[Sinj|Sinj, Croatia]]]]
Karst is most strongly developed in dense [[carbonate rock]], such as limestone, that is thinly [[Bed (geology)|bedded]] and highly [[Joint (geology)|fractured]]. Karst is not typically well developed in [[chalk]], because chalk is highly porous rather than dense, so the flow of groundwater is not concentrated along fractures. Karst is also most strongly developed where the water table is relatively low, such as in uplands with [[Entrenched river|entrenched valleys]], and where rainfall is moderate to heavy. This contributes to rapid downward movement of groundwater, which promotes dissolution of the bedrock, whereas standing groundwater becomes saturated with carbonate minerals and ceases to dissolve the bedrock.<ref name="thornbury-1969">{{cite book |last1=Thornbury |first1=William D. |title=Principles of geomorphology |date=1969 |publisher=Wiley |location=New York |isbn=0471861979 |pages=303–344 |edition=2d}}</ref><ref>{{cite web |title=Karst Landscapes of Illinois: Dissolving Bedrock and Collapsing Soil |url=https://isgs.illinois.edu/outreach/geology-resources/karst-landscapes-illinois-dissolving-bedrock-and-collapsing-soil |website=Prairie Research Institute |publisher=Illinois State Geological Survey |access-date=26 December 2020 |archive-date=2 December 2020 |archive-url=https://web.archive.org/web/20201202003934/https://isgs.illinois.edu/outreach/geology-resources/karst-landscapes-illinois-dissolving-bedrock-and-collapsing-soil |url-status=dead }}</ref>

===Chemistry of dissolution===
The [[carbonic acid]] that causes karst features is formed as rain passes through [[Earth's atmosphere]] picking up [[carbon dioxide]] ({{CO2}}), which readily dissolves in the water. Once the rain reaches the ground, it may pass through [[soil]] that provides additional {{CO2}} produced by [[soil respiration]]. Some of the dissolved carbon dioxide reacts with the water to form a weak carbonic acid solution, which dissolves [[calcium carbonate]].<ref>{{cite web |last1=Grove |first1=Glenn E. |title=Karst Features and the Dissolution of Carbonate Rocks in Crawford County |url=https://www.in.gov/dnr/water/files/crawford_text_karst.pdf |publisher=Indiana Department of Natural Resources, Division of Water, Resource Assessment Section |access-date=26 December 2020 |date=September 2003}}</ref> The primary reaction sequence in limestone dissolution is the following:<ref>{{cite encyclopedia |last1=Wolfgang |first1=Dreybrodt |year=2004 |title=Dissolution: Carbonate rocks |encyclopedia=Encyclopedia of Caves and Karst Science |pages=295–298 |url=https://www.researchgate.net/publication/313171146 |access-date=26 December 2020}}</ref>
[[File:Kostivere karst area.jpg|thumb|upright|[[Kostivere Landscape Conservation Area|Kostivere karst area]] in Estonia]]
:{{chem2|H2O + CO2 -> H2CO3}}
:{{chem2|CaCO3 + H2CO3 -> Ca(2+) + 2 HCO3−}}

In very rare conditions, oxidation can play a role. Oxidation played a major role in the formation of ancient [[Lechuguilla Cave]] in the US state of [[New Mexico]]<ref>{{cite journal |last1=Davis |first1=D.G. |year=2000 |title=Extraordinary features of Lechuguilla Cave, Guadalupe Mountains, New Mexico |journal=Journal of Cave and Karst Studies |volume=62 |number=2 |pages=147–157 |citeseerx=10.1.1.521.9303 }}</ref> and is presently active in the [[Frasassi Caves]] of Italy.<ref>{{cite journal |last1=Galdenzi |first1=S. |last2=Maruoka |first2=T. |year=2003 |title=Gypsum deposits in the Frasassi Caves, central Italy |journal=Journal of Cave and Karst Studies |volume=65 |number=2 |pages=111–125 |url=https://www.researchgate.net/publication/279620470 |access-date=24 February 2021}}</ref> 
[[File:karst Dent-de-Crolle-8.jpg|right|thumb|[[Limestone pavement]] on [[Dent de Crolles|Dent de Crolles, France]]]]
The oxidation of [[sulfide]]s leading to the formation of [[sulfuric acid]] can also be one of the corrosion factors in karst formation. As [[oxygen]]-rich surface waters seep into deep anoxic karst systems, they bring oxygen, which reacts with sulfide present in the system ([[pyrite]] or [[hydrogen sulfide]]) to form sulfuric acid ({{chem2|H2SO4}}). Sulfuric acid then reacts with calcium carbonate, causing increased erosion within the limestone formation. This [[Chain reaction|chain of reaction]]s is:
:{{chem2|H2S + 2 O2 -> H2SO4}} (sulfide oxidation)
:{{chem2|H2SO4 + 2 H2O -> SO4(2-) + 2 H3O+}} (sulfuric acid dissociation)
:{{chem2|CaCO3 + 2 H3O+ -> Ca(2+) + H2CO3 + 2 H2O}} (calcium carbonate dissolution)
:{{chem2|Ca(2+) + SO4(2-) -> CaSO4}} (formation of calcium sulfate)
:{{chem2|CaSO4 + 2 H2O -> [CaSO4*2H2O]}} (formation of gypsum)

This reaction chain forms [[gypsum]].<ref>{{cite journal |year=2008 |first1=S. |last1=Galdenzi |first2=M. |last2=Cocchioni |first3=L. |last3=Morichetti |first4=V. |last4=Amici |first5=S. |last5=Scuri |display-authors=3|title=Sulfidic ground water chemistry in the Frasassi Cave, Italy |journal=Journal of Cave and Karst Studies |volume=70 |issue=2 |pages=94–107 |url=http://wvvw.caves.org/pub/journal/PDF/v70/cave-70-02-94.pdf |access-date=2012-11-29 |archive-date=2016-03-04 |archive-url=https://web.archive.org/web/20160304044009/http://wvvw.caves.org/pub/journal/PDF/v70/cave-70-02-94.pdf |url-status=dead }}</ref>

== Morphology ==
[[File:Rubaksa tufa plug.jpg|thumb|[[Rubaksa]] [[tufa]] plug in Ethiopia]]
The karstification of a landscape may result in a variety of large- or small-scale features both on the surface and beneath. On exposed surfaces, small features may include solution flutes (or rillenkarren), [[Stream|runnels]], [[limestone pavement]] (clints and grikes), [[Kamenitza (Geomorphology)|kamenitzas]] collectively called karren or lapiez. Medium-sized surface features may include [[sinkhole]]s or [[cenote]]s (closed basins), vertical shafts, [[foibe]] (inverted funnel shaped sinkholes), disappearing streams, and reappearing [[karst spring|spring]]s.

Large-scale features may include [[limestone pavement]]s, [[polje]]s, and karst valleys. Mature karst landscapes, where more bedrock has been removed than remains, may result in [[tower karst|karst towers]], or [[mogote|haystack/eggbox]] landscapes. Beneath the surface, complex underground drainage systems (such as karst [[Aquifer#Porous versus karst|aquifers]]) and extensive [[cave]]s and cavern systems may form.<ref name="thornbury-1969" />

Erosion along limestone shores, notably in the [[tropics]], produces karst topography that includes a sharp makatea surface above the normal reach of the sea, and undercuts that are mostly the result of biological activity or [[bioerosion]] at or a little above [[mean sea level]].<ref>{{cite journal |last1=Mylroie |first1=J.E. |last2=Vacher |first2=H.L. |year=1999 |title=A conceptual view of carbonate island karst |journal=Karst Waters Institute Special Publication |volume=5 |pages=48–57 |url=https://apps.dtic.mil/dtic/tr/fulltext/u2/a369937.pdf#page=56 |archive-url=https://web.archive.org/web/20210429045355/https://apps.dtic.mil/dtic/tr/fulltext/u2/a369937.pdf#page=56 |url-status=live |archive-date=April 29, 2021 |access-date=26 December 2020}}</ref> Some of the most dramatic of these formations can be seen in [[Thailand]]'s [[Phangnga Bay]] and at [[Halong Bay]] in [[Vietnam]].

Calcium carbonate dissolved into water may precipitate out where the water discharges some of its dissolved carbon dioxide. Rivers which emerge from springs may produce [[tufa]] terraces, consisting of layers of calcite deposited over extended periods of time. In caves, a variety of features collectively called [[speleothem]]s are formed by deposition of calcium carbonate and other dissolved minerals.

=== Interstratal karst ===
Interstratal karst is a karst landscape which is developed beneath a cover of insoluble rocks. Typically this will involve a cover of [[sandstone]] overlying limestone strata undergoing solution. In the United Kingdom for example extensive doline fields have developed at [[Cefn yr Ystrad]], [[Mynydd Llangatwg]] and [[Mynydd Llangynidr]] in South Wales across a cover of [[Twrch Sandstone]] which overlies concealed [[Carboniferous Limestone]], the last-named locality having been declared a [[site of special scientific interest]] in respect of it.<ref>{{cite web|url=http://www.blaenau-gwent.gov.uk/documents/Documents_Environment/PH4_SSSI_Notification_Letter.pdf |title=Archived copy |access-date=2013-03-03 |url-status=dead |archive-url=https://web.archive.org/web/20151120022422/http://www.blaenau-gwent.gov.uk/documents/Documents_Environment/PH4_SSSI_Notification_Letter.pdf |archive-date=2015-11-20 }}</ref>

[[File:Karst landscape with irregularly shaped hills near Kasi Laos 27Nov2005.jpg|thumb|Karst landscape with irregularly shaped hills, near Kasi, Laos]]
=== Kegelkarst, salt karst, and karst forests ===
Kegelkarst is a type of tropical karst terrain with numerous cone-like hills, formed by cockpits, [[mogote]]s, and [[polje]]s and without strong fluvial erosion processes. This terrain is found in Cuba, Jamaica, Indonesia, Malaysia, the Philippines, Puerto Rico, southern China, Myanmar, Thailand, Laos and Vietnam.<ref>Whittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, 1984, p 292. {{ISBN|0-14-051094-X}}.</ref>

Salt karst (or 'halite karst') is developed in areas where [[salt]] is undergoing solution underground. It can lead to surface depressions and collapses which present a geo-hazard.<ref>{{cite web |last1=Cooper |first1=Anthony H. |title=Halite karst geohazards (natural and man-made) in the United Kingdom |url=https://nora.nerc.ac.uk/id/eprint/6218/2/Halite_karst_geohazards_Cooper_Env_Geol_vol42_505-512.pdf |publisher=BGS/NERC |access-date=9 October 2022}}</ref>

Karst areas tend to have unique types of forests. The karst terrain is difficult for humans to traverse, so that their ecosystems are often relatively undisturbed. The soil tends to have a high pH, which encourages growth of unusual species of orchids, palms, mangroves, and other plants.<ref>{{cite web |last1=Evans |first1=Monica |title=Karst forests: the labyrinthian wildlands of green and bedrock |url=https://news.globallandscapesforum.org/43769/karst-forests-the-labyrinthian-wildlands-of-green-and-bedrock/ |website=Global Landscapes Forum |date=2020-04-15}}</ref>

=== Paleokarst ===
Paleokarst or palaeokarst is a development of karst observed in geological history and preserved within the rock sequence, effectively a fossil karst. There are for example palaeokarst surfaces exposed within the Clydach Valley Subgroup of the [[Carboniferous Limestone]] sequence of [[South Wales]] which developed as sub-aerial [[weathering]] of recently formed limestones took place during periods of non-deposition within the early part of the period. Sedimentation resumed and further limestone strata were deposited on an irregular karst surface, the cycle recurring several times in connection with fluctuating sea levels over prolonged periods.<ref>{{cite book |last1=Howells |first1=M.F |title=British Regional Geology:Wales |date=2007 |publisher=British Geological Survey |location=Keyworth, Nottingham |isbn=978-085272584-9 |page=118}}</ref>

=== Pseudokarst ===
Pseudokarsts are similar in form or appearance to karst features but are created by different mechanisms. Examples include [[lava]] caves and [[granite]] [[tor (geography)|tors]]—for example, Labertouche Cave in [[Victoria (Australia)|Victoria, Australia]]—and [[paleocollapse]] features. [[Mud Caves]] are an example of pseudokarst.

== Hydrology ==
[[File:KarstterrainUSGS.jpg|thumb|upright=2|alt=Cross section of karst terrain showing topographic features and water flow paths.|Features typical of well-developed karst terrain]]
[[File: Puerto Princesa Underground River.jpg|thumb|The [[Puerto-Princesa Subterranean River National Park|Puerto Princesa Underground River]], Philippines]]

Karst formations have unique hydrology, resulting in many unusual features. A [[karst fenster]] (karst window) occurs when an underground stream emerges onto the surface between layers of rock, [[waterfall#Types of waterfalls|cascades]] some distance, and then disappears back down, often into a sinkhole.

Rivers in karst areas may disappear underground a number of times and spring up again in different places, even under a different name, like [[Ljubljanica]], the "river of seven names".

Another example of this is the [[Popo Agie Wilderness|Popo Agie River]] in [[Fremont County, Wyoming]], where, at a site named "The Sinks" in [[Sinks Canyon State Park]], the river flows into a cave in a formation known as the Madison Limestone and then rises again {{convert|1/2|mi|m|order=flip|abbr=on}} down the canyon in a placid pool.

A [[Turlough (lake)|turlough]] is a unique type of seasonal lake found in Irish karst areas which are formed through the annual welling-up of water from the underground water system.

=== Aquifers ===
{{Main|Aquifer#Karst}}
[[File:MammothCaveNPS.jpg|thumb|left |alt=Several people in a jon boat on a river inside a cave. |Water in karst aquifers flows through open conduits where water flows as underground streams.]]
Karst aquifers typically develop in [[limestone]]. Surface water containing natural [[carbonic acid]] moves down into small fissures in limestone. This carbonic acid gradually dissolves limestone thereby enlarging the fissures. The enlarged fissures allow a larger quantity of water to enter which leads to a progressive enlargement of openings. Abundant small openings store a large quantity of water. The larger openings form a conduit system that drains the aquifer to springs.<ref>{{cite book |last=Dreybrodt |first=Wolfgang |date=1988 |title=Processes in karst systems: physics, chemistry, and geology |volume=4 |location=Berlin |publisher=Springer |pages=2–3 |isbn=978-3-642-83354-0 |doi=10.1007/978-3-642-83352-6 |series=Springer Series in Physical Environment }}</ref>

Characterization of karst aquifers requires field exploration to locate [[sinkhole|sinkholes, swallets]], [[Losing stream|sinking streams]], and [[Spring (hydrology)|springs]] in addition to studying [[geological map]]s.<ref name="DelineationGrdwtrBasinsTaylor">{{cite book |last=Taylor |first=Charles |date=1997 |title=Delineation of ground-water basins and recharge areas for municipal water-supply springs in a karst aquifer system in the Elizabethtown area, Northern Kentucky |url=https://pubs.usgs.gov/wri/1996/4254/report.pdf |location=Denver, Colorado |publisher=U.S. Geological Survey |series=Water-Resources Investigations Report 96-4254 |doi=10.3133/wri964254 }}</ref>{{rp|4}} Conventional hydrogeologic methods such as aquifer tests and potentiometric mapping are insufficient to characterize the complexity of karst aquifers, and need to be supplemented with [[Dye tracing|dye traces]], measurement of spring discharges, and analysis of water chemistry.<ref>{{cite book |last1=Taylor |first1=Charles |last2=Greene |first2=Earl |date=2008 |title=Field Techniques for Estimating Water Fluxes Between Surface Water and Ground Water |chapter=Hydrogeologic characterization and methods used in the investigation of karst hydrology. |chapter-url=https://pubs.usgs.gov/tm/04d02/pdf/TM4-D2-chap3.pdf |archive-url=https://web.archive.org/web/20081102202902/http://pubs.usgs.gov/tm/04d02/pdf/TM4-D2-chap3.pdf |archive-date=2008-11-02 |url-status=live |series=Techniques and Methods 4–D2 |publisher=U.S. Geological Survey |page=107 }}</ref> U.S. Geological Survey dye tracing has determined that conventional groundwater models that assume a uniform distribution of porosity are not applicable for karst aquifers.<ref>{{cite journal |last1=Renken |first1=R. |last2=Cunningham |first2=K. |last3=Zygnerski |first3=M. |last4=Wacker |first4=M. |last5=Shapiro |first5=A. |last6=Harvey |first6=R. |last7=Metge |first7=D. |last8=Osborn |first8=C. |last9=Ryan |first9=J. |date=November 2005 |title=Assessing the Vulnerability of a Municipal Well Field to Contamination in a Karst Aquifer |journal= Environmental and Engineering Geoscience |publisher=GeoScienceWorld|volume=11 |number=4 |page=320 |doi=10.2113/11.4.319 |bibcode=2005EEGeo..11..319R |citeseerx=10.1.1.372.1559 }}</ref>
[[File:Source de la Loue3.JPG|thumb|A [[karst spring]] in the [[Jura Mountains]] near [[Ouhans]] in eastern France at the source of the river [[Loue]]]]

Linear alignment of surface features such as straight stream segments and sinkholes develop along [[Fracture (geology)|fracture traces]]. Locating a well in a fracture trace or intersection of fracture traces increases the likelihood to encounter good water production.<ref>{{cite book |last=Fetter |first=Charles |date=1988 |title=Applied Hydrology |location=Columbus, Ohio |publisher=Merrill |pages=294–295 |isbn=978-0-675-20887-1 }}</ref> Voids in karst aquifers can be large enough to cause destructive collapse or [[subsidence]] of the ground surface that can initiate a catastrophic release of contaminants.<ref name="FieldMethodsGeoHydrogeo">{{cite book|last1= Assaad |first1= Fakhry |last2=LaMoreaux |first2=Philip |last3=Hughes |first3=Travis |date=2004 |title=Field methods for geologists and hydrogeologists |location=Berlin, Germany |publisher= Springer-Verlag Berlin Heidelberg |isbn= 978-3-540-40882-6 |doi=10.1007/978-3-662-05438-3}}</ref>{{rp|3–4}} 

Groundwater flow rate in karst aquifers is much more rapid than in porous aquifers. For example, in the Barton Springs Edwards aquifer, dye traces measured the karst groundwater flow rates from 0.5 to 7 miles per day (0.8 to 11.3&nbsp;km/d).<ref>{{cite journal |last1=Scanlon |first1=Bridget|author1-link= Bridget Scanlon |last2=Mace |first2=Robert |last3=Barrett |first3=Michael |last4=Smith |first4=Brian |date=2003 |title= Can we simulate regional groundwater flow in a karst system using equivalent porous media models? Case study, Barton Springs Edwards aquifer, USA |journal= Journal of Hydrology |publisher=Elsevier Science |volume=276 |issue= 1–4|page=142 |doi= 10.1016/S0022-1694(03)00064-7 |bibcode=2003JHyd..276..137S|s2cid=16046040 }}</ref> The rapid groundwater flow rates make karst aquifers much more sensitive to groundwater contamination than porous aquifers.<ref name="DelineationGrdwtrBasinsTaylor" />{{rp|1}}

[[Groundwater]] in karst areas is also just as easily [[Water pollution|polluted]] as surface streams, because Karst formations are cavernous and highly permeable, resulting in reduced opportunity for contaminant filtration.

[[Water well|Well water]] may also be unsafe as the water may have run unimpeded from a sinkhole in a cattle pasture, bypassing the normal filtering that occurs in a [[Aquifer#Porous versus karst|porous aquifer]]. Sinkholes have often been used as farmstead or community [[landfill|trash dumps]]. Overloaded or malfunctioning [[septic tank]]s in karst landscapes may dump raw sewage directly into underground channels.

Geologists are concerned with these negative effects of human activity on karst hydrology which, {{as of|2007|lc=y}}, supplied about 25% of the global demand for drinkable water.<ref>{{cite journal |last1=Parise |first1=M. |last2=Gunn |first2=J. |title=Natural and anthropogenic hazards in karst areas: an introduction |url=https://sp.lyellcollection.org/content/279/1/1 |journal=Geological Society, London, Special Publications |access-date=9 October 2021 |pages=1–3 |language=en |doi=10.1144/SP279.1 |date=1 January 2007|volume=279 |issue=1 |bibcode=2007GSLSP.279....1P |s2cid=130950517 |url-access=subscription }}</ref>

=== Effects of karst hydrology ===
Farming in karst areas must take into account the lack of surface water. The soils may be fertile enough, and rainfall may be adequate, but rainwater quickly moves through the crevices into the ground, sometimes leaving the surface soil parched between rains.

The karst topography also poses peculiar difficulties for human inhabitants. Sinkholes can develop gradually as surface openings enlarge, but progressive [[erosion]] is frequently unseen until the roof of a cavern suddenly collapses. Such events have swallowed homes, cattle, cars, and farm machinery. In the United States, sudden collapse of such a cavern-sinkhole swallowed part of the collection of the [[National Corvette Museum]] in [[Bowling Green, Kentucky]] in 2014.<ref>{{Cite web|url=https://www.cnn.com/2014/02/13/travel/corvette-museum-sinkhole/index.html|title=Mood somber, repairs uncertain as Corvette museum opens|last=Patterson|first=Thom|website=CNN|date=13 February 2014|access-date=2019-08-26}}</ref>

== Karst areas ==
{{Main|List of karst areas}}
[[File:Yunnanshilin2.jpg|thumb|upright=1.3|[[Stone Forest|Lunan Stone Forest]], Yunnan, China]]
[[File:Kostivere karstiala, Kostivere karst area, spring 2021.webm|thumb|Drone video of Kostivere karst area in Estonia (2021)]]

The world's largest limestone karst is Australia's [[Nullarbor Plain]]. Slovenia has the world's highest risk of sinkholes, while the western [[Highland Rim]] in the eastern United States is at the second-highest risk of karst sinkholes.<ref>{{Cite web|url=http://www.apsu.edu/news/harned-bowl-work-not-blame-new-sinkhole-say-experts|archive-url=https://web.archive.org/web/20140522031858/http://www.apsu.edu/news/harned-bowl-work-not-blame-new-sinkhole-say-experts|url-status=dead|archive-date=May 22, 2014|title=Austin Peay State University : Harned Bowl work not to blame for new sinkhole, say experts|date=May 22, 2014|access-date=Dec 31, 2019}}</ref><ref>{{Cite web|url=https://www.clarksvilleonline.com/2009/02/25/what-is-karst-topography-and-why-should-you-care/|title=What is Karst topography and why should you care?|date=Feb 25, 2009|access-date=Dec 31, 2019}}</ref>

In Canada, [[Wood Buffalo National Park]], Northwest Territories contains areas of karst sinkholes.<ref>{{Cite book|last=Smith|first=D.G.|title=Landforms of Alberta interpreted from airphotos and satellite imagery.|publisher=Alberta Remote Sensing Center. Alberta Environment|year=1987|isbn=0-919975-10-0|location=Edmonton, Alberta|pages=81}}</ref> Mexico hosts important karst regions in the [[Yucatán Peninsula]] and [[Chiapas]].<ref>{{Cite journal|author1=Mora, L.|author2=Bonifaz, R.|author3=López-Martínez, R.|year=2016|title=Unidades geomorfológicas de la cuenca del Río Grande de Comitán, Lagos de Montebello, Chiapas-México|journal=Boletín de la Sociedad Geológica Mexicana|language=es|volume=68|issue=3|pages=377–394|doi=10.18268/BSGM2016v68n3a1|bibcode=2016BoSGM..68..377M |doi-access=free}}</ref> The [[West of Ireland]] is home to [[The Burren]], a karst limestone area. The [[South China Karst]] in the provinces of [[Guizhou]], [[Guangxi]], and [[Yunnan]] provinces is a UNESCO World Heritage Site.

== List of terms for karst-related features ==
{{See also|Speleothem}}

Many karst-related terms derive from [[South Slavic languages]], entering scientific vocabulary through early research in the Western Balkan Dinaric Alpine karst.

* [[Abîme]], a vertical shaft in karst that may be very deep and usually opens into a network of subterranean passages
* [[Cenote]], a deep sinkhole, characteristic of Mexico, resulting from collapse of limestone bedrock that exposes groundwater underneath
* [[Sinkhole|Doline]], also sink or sinkhole, is a closed depression draining underground in karst areas. The word ''doline'' comes from the South Slavic word ''dolina'' 'valley'.
* [[Foibe]], an inverted funnel-shaped sinkhole
* [[Karst window]] (also known as a "karst fenster"), a feature where a spring emerges briefly, with the water discharge then abruptly disappearing into a nearby sinkhole
* [[Karst spring]], a spring emerging from karst, originating a flow of water on the surface
* [[Limestone pavement]], a landform consisting of a flat, incised surface of exposed limestone that resembles an artificial pavement
* [[Losing stream]], sinking river or [[ponornica]] in South Slavic languages.
* [[Polje]] (karst polje, karst field), a large flat specifically karst plain. The word ''polje'' derives from South Slavic languages.
* [[Ponor]], same as [[estavelle]], sink or sinkhole in South Slavic languages, where surface flow enters an underground system
* [[Scowle]], porous irregular karst landscape in a region of England.
* [[Turlough (lake)|Turlough]] (turlach), a type of disappearing lake characteristic of [[Ireland|Irish]] karst.
* [[Uvala (landform)|Uvala]], a collection of multiple smaller individual sinkholes that coalesce into a compound sinkhole. The term derives from South Slavic languages.

==Karst studies==
The study of the various aspects of karst regions is called karst studies,<ref>{{cite web |title=Karst Studies |url=https://floridadep.gov/fgs/research/content/karst-studies |website=Florida Department of Environmental Protection |access-date=March 15, 2025}}</ref> karst science,<ref>{{cite book |last1=Gunn |first1=John |title=Encyclopedia of Caves and Karst Science |date=2004 |publisher=Fitzroy Dearborn |location=New York}}</ref> or karstology.<ref>{{cite book |last1=Gilli |first1=Éric |title=Karstology: Karsts, Caves and Springs |date=2015 |publisher=CRC Press |location=Boca Raton, FL}}</ref> This includes biological, chemical, ecological, geomorphological, hydrogeological, hydrological, political, socio-economical, and other processes over a variety of spatial and temporal scales in karst regions, with the purpose of understanding karst aquifers and ecosystems, and the development of the surface and underground structure, so that the environment can be protected and human activities planned effectively.<ref>{{cite report |last=Bonacci |first=Ognjen |date=2019 |title=Karstology -how can it help in sustainable development? |url=https://www.researchgate.net/publication/338149576 }}</ref> Prominent karst researchers include [[Jovan Cvijić]] and [[William Morris Davis]].

== See also ==
{{div col|colwidth=30em}}
* {{Annotated link|Alvar}}
* {{Annotated link|Gryke}}
* {{annotated link|Glaciokarst}}
* {{annotated link|Glossary of landforms}}
* {{annotated link|Speleology}}
* {{annotated link|Subterranean river}}
* {{annotated link|Thermokarst}}
{{div col end}}

{{clear}}

== References ==
{{Reflist}}

== Further reading ==
* Ford, D.C., Williams, P., ''Karst Hydrogeology and Geomorphology'', John Wiley and Sons Ltd., 2007, {{ISBN|978-0-470-84996-5}}
* Jennings, J.N., ''Karst Geomorphology'', 2nd ed., Blackwell, 1985, {{ISBN|0-631-14032-8}}
* Palmer, A.N., ''Cave Geology'', 2nd Printing, Cave Books, 2009, {{ISBN|978-0-939748-66-2}}
* [[Marjorie Sweeting|Sweeting, M.M.]], ''Karst Landforms'', Macmillan, 1973, {{ISBN|0-231-03623-X}}
* van Beynen, P. (Ed.), ''Karst management'', Springer, 2011, {{ISBN|978-94-007-1206-5}} 
* Vermeulen, J.J., Whitten, T., "Biodiversity and Cultural Property in the Management of Limestone Resources in East Asia: Lessons from East Asia", The World Bank, 1999, {{ISBN|978-0-821345-08-5}}

== External links ==
{{Commons and category|Karst}}
{{Wikisource1911Enc|Karst}}
* [https://web.archive.org/web/20120119214928/http://www.network.speleogenesis.info/index.php Speleogenesis Network, a communication platform for physical speleology and karst science research]
* [http://www.speleogenesis.info/glossary/index.php Speleogenesis and Karst Aquifers] {{Webarchive|url=https://web.archive.org/web/20100423192906/http://www.speleogenesis.info/glossary/index.php |date=2010-04-23 }} – a large glossary of Karst related terms
* [http://carsologica.zrc-sazu.si/ Acta Carsologica] – research papers and reviews in all the fields related to karst
* [http://cdk-pr.org/ CDK Citizens of the Karst] – Citizens of the Karst, a non profit NGO dedicated to the protection of the Puerto Rican Karst (English site available)
* [http://www.goodearthgraphics.com/virtcave/karst/karst.html The Virtual Cave's page on karst landforms]
* [http://digital.lib.usf.edu/?K26 Karst Information Portal] - an open-access digital library linking scientists, managers, and explorers

{{Caves}}
{{Subterranea}}

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[[Category:Karst| ]]
[[Category:Landforms]]
[[Category:Limestone formations]]
[[Category:Geomorphology]]
[[Category:Dinaric karst formations]]