Karst

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Skocjan Caves, Slovenia Skocjan Caves (3802558032).jpg
Škocjan Caves, Slovenia
Global distribution of major outcrops of carbonate rocks (mainly limestone, except evaporites) Carbonate-outcrops world.jpg
Global distribution of major outcrops of carbonate rocks (mainly limestone, except evaporites)
The Puerto Princesa Underground River, Philippines Puerto Princesa Underground River.jpg
The Puerto Princesa Underground River, Philippines

Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. [1] It has also been documented for more weathering-resistant rocks, such as quartzite, given the right conditions. [2] Subterranean drainage may limit surface water, with few to no rivers or lakes. However, 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.

Topography The study of the shape and features of the surface of the Earth and other observable astronomical objects

Topography is the study of the shape and features of land surfaces. The topography of an area could refer to the surface shapes and features themselves, or a description.

Limestone Sedimentary rocks made of calcium carbonate

Limestone is a carbonate sedimentary rock that is often composed of the skeletal fragments of marine organisms such as coral, foraminifera, and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). A closely related rock is dolomite, which contains a high percentage of the mineral dolomite, CaMg(CO3)2. In old USGS publications, dolomite was referred to as magnesian limestone, a term now reserved for magnesium-deficient dolomites or magnesium-rich limestones.

Dolomite (rock) Sedimentary carbonate rock that contains a high percentage of the mineral dolomite

Dolomite (also known as dolostone, dolomite rock or dolomitic rock) is a sedimentary carbonate rock that contains a high percentage of the mineral dolomite, CaMg(CO3)2. In old USGS publications, it was referred to as magnesian limestone, a term now reserved for magnesium-deficient dolomites or magnesium-rich limestones. Dolomite has a stoichiometric ratio of nearly equal amounts of magnesium and calcium. Most dolomites formed as a magnesium replacement of limestone or lime mud before lithification. Dolomite is resistant to erosion and can either contain bedded layers or be unbedded. It is less soluble than limestone in weakly acidic groundwater, but it can still develop solution features (karst) over time. Dolomite can act as an oil and natural gas reservoir.

Contents

The study of karst is considered of prime importance in petroleum geology because as much as 50% of the world's hydrocarbon reserves are hosted in porous karst systems. [3]

Petroleum geology is the study of origin, occurrence, movement, accumulation, and exploration of hydrocarbon fuels. It refers to the specific set of geological disciplines that are applied to the search for hydrocarbons.

Etymology

The English word karst was borrowed from German Karst in the late 19th century, [4] which entered German much earlier. [5] According to one interpretation the term is derived from the German name for a number of geological, geomorphological, and hydrological features found within the range of the Dinaric Alps, stretching from the northeastern corner of Italy above the city of Trieste (at the time part of the Austrian Littoral), across the Balkan peninsula along the coast of the eastern Adriatic to Kosovo and North Macedonia, where the massif of the Šar Mountains begins, and more specifically the karst zone at the northwestern-most section, described in early topographical research as a plateau, between Italy and Slovenia.

A range, in geography, is a chain of hills or mountains, or a somewhat linear, complex mountainous or hilly area.

Dinaric Alps mountain range in Southeastern Europe

The Dinaric Alps, also commonly Dinarides, are a mountain range in Southern and Southeastern Europe, separating the continental Balkan Peninsula from the Adriatic Sea. They stretch from Italy in the northwest through Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Montenegro, Kosovo to Albania in the southeast.

Italy republic in Southern Europe

Italy, officially the Italian Republic, is a European country consisting of a peninsula delimited by the Alps and surrounded by several islands. Located in the middle of the Mediterranean sea and traversed along its length by the Apennines, Italy has a largely temperate seasonal and Mediterranean climate. The country covers a total area of 301,340 km2 (116,350 sq mi), and land area of 294,140 km2 (113,570 sq mi), and shares open land borders with France, Switzerland, Austria, Slovenia, and the enclaved microstates of Vatican City and San Marino. Italy has a territorial exclave in Switzerland (Campione) and a maritime exclave in the Tunisian Sea (Lampedusa). With around 60 million inhabitants, Italy is the fourth-most populous member state of the European Union.

In the local South Slavic languages, all variations of the word are derived from a Romanized Illyrian base (yielding Latin : carsus, Dalmatian Romance carsus), later metathesized from the reconstructed form *korsъ into forms such as Serbo-Croatian : krš, kras. [6] [7] [8] [9] Languages preserving the older, non-metathesized form include Italian : Carso, German : Karst, and Albanian : karsti; the lack of metathesis precludes borrowing from any of the South Slavic languages, specifically Slovene. [10] [11] The Slovene common noun kras was first attested in the 18th century, and the adjective form kraški in the 16th century. [12] As a proper noun, the Slovene form Grast was first attested in 1177. [13]

South Slavic languages Language family

The South Slavic languages are one of three branches of the Slavic languages. There are approximately 30 million speakers, mainly in the Balkans. These are separated geographically from speakers of the other two Slavic branches by a belt of German, Hungarian and Romanian speakers. The first South Slavic language to be written was the variety spoken in Thessaloniki, now called Old Church Slavonic, in the ninth century. It is retained as a liturgical language in some South Slavic Orthodox churches in the form of various local Church Slavonic traditions.

Italo-Dalmatian languages Language family

The Italo-Dalmatian languages, or Central Romance languages, are a group of Romance languages spoken in Italy, Corsica (France) and formerly in Dalmatia (Croatia).

Metathesis is the transposition of sounds or syllables in a word or of words in a sentence. Most commonly, it refers to the interchange of two or more contiguous sounds, known as adjacent metathesis or local metathesis:

Ultimately, the word is of Mediterranean origin. It has been suggested that the word may derive from the Proto-Indo-European root karra- 'rock'. [14] The name may also be connected to the oronym Kar(u)sádios oros cited by Ptolemy, and perhaps also to Latin Carusardius. [12] [13]

Proto-Indo-European language Ancestor of the Indo-European language family

Proto-Indo-European (PIE) is the linguistic reconstruction of the ancient common ancestor of the Indo-European languages, the most widely spoken language family in the world.

Toponymy is the study of place names (toponyms), their origins, meanings, use, and typology.

Ptolemy 2nd-century Greco-Egyptian writer and astronomer

Claudius Ptolemy was a mathematician, astronomer, geographer and astrologer. He lived in the city of Alexandria in the Roman province of Egypt, under the rule of the Roman Empire, had a Latin name, which several historians have taken to imply he was also a Roman citizen, cited Greek philosophers, and used Babylonian observations and Babylonian lunar theory. The 14th-century astronomer Theodore Meliteniotes gave his birthplace as the prominent Greek city Ptolemais Hermiou in the Thebaid. This attestation is quite late, however, and there is no other evidence to confirm or contradict it. He died in Alexandria around AD 168.

Early studies

Karst limestones as statuary in Shenyang Imperial Palace, Shenyang, China Karstic stones Shenyang Imperial Palace.jpg
Karst limestones as statuary in Shenyang Imperial Palace, Shenyang, China

Johann Weikhard von Valvasor, a pioneer of the study of karst in Slovenia and a fellow of the Royal Society for Improving Natural Knowledge, London, introduced the word karst to European scholars in 1689, describing the phenomenon of underground flows of rivers in his account of Lake Cerknica. [15]

Johann Weikhard von Valvasor Carnolian scientist

Johann Weikhard Freiherr von Valvasor or Johann Weichard Freiherr von Valvasor or simply Valvasor was a natural historian and polymath from Carniola, present-day Slovenia, and a fellow of the Royal Society in London.

Slovenia republic in Central Europe

Slovenia, officially the Republic of Slovenia, is a country located in southern Central Europe at a crossroads of important European cultural and trade routes. It is bordered by Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the southeast, and the Adriatic Sea to the southwest. It covers 20,273 square kilometers (7,827 sq mi) and has a population of 2.07 million. One of the successor states of the former Yugoslavia, Slovenia is a parliamentary republic and a member of the United Nations, of the European Union, and of NATO. The capital and largest city is Ljubljana.

Royal Society National academy of science in the United Kingdom

The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national Academy of Sciences. Founded on 28 November 1660, it was granted a royal charter by King Charles II as "The Royal Society". It is the oldest national scientific institution in the world. The society fulfils a number of roles: promoting science and its benefits, recognising excellence in science, supporting outstanding science, providing scientific advice for policy, fostering international and global co-operation, education and public engagement. It also performs these roles for the smaller countries of the Commonwealth.

Jovan Cvijić greatly advanced the knowledge of karst regions, so much that he became known as the "father of karst geomorphology". Primarily discussing the karstic regions of the Balkans, Cvijić's 1893 publication Das Karstphänomen describes landforms such as karren, dolines and poljes. [3] In a 1918 publication, Cvijić proposed a cyclical model for karstic landscape development. [3] [16] Karst hydrology emerged as a discipline in the late 1950s and early 1960s in France. Previously, the activities of cave explorers, called speleologists, had been dismissed as more of a sport than a science, meaning that underground karstic caves and their associated watercourses were, from a scientific perspective, understudied. [17]

Chemistry

Doline in the causse de Sauveterre, Lozere, France Causse de Sauveterre doline.jpg
Doline in the causse de Sauveterre, Lozère, France

The development of karst occurs whenever acidic water starts to break down the surface of bedrock near its cracks, or bedding planes. As the bedrock (typically limestone or dolomite) continues to degrade, its cracks tend to get bigger. As time goes on, these fractures will become wider, and eventually a drainage system of some sort may start to form underneath. If this underground drainage system does form, it will speed up the development of karst formations there because more water will be able to flow through the region, giving it more erosive power. [18]

Dissolution mechanism

The carbonic acid that causes karstic features is formed as rain passes through Earth's atmosphere picking up carbon dioxide (CO2), which dissolves in the water. Once the rain reaches the ground, it may pass through soil that can provide much more CO2 to form a weak carbonic acid solution, which dissolves calcium carbonate. The primary reaction sequence in limestone dissolution is the following:

H2O+CO2H2CO3
CaCO3+H2CO3Ca2++2 HCO
3
Li River, Guilin, China 1 li jiang guilin yangshuo 2011.jpg
Li River, Guilin, China

In particular and very rare conditions such as encountered in the past in Lechuguilla Cave in New Mexico (and more recently in the Frasassi Caves in Italy), other mechanisms may also play a role. The oxidation of sulfides leading to the formation of sulfuric acid can also be one of the corrosion factors in karst formation. As oxygen (O2)-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 (H2SO4). Sulfuric acid then reacts with calcium carbonate, causing increased erosion within the limestone formation. This chain of reactions is:

H2S+2 O2H2SO4(sulfide oxidation)
H2SO4+2 H2OSO2−
4
+2 H3O+(sulfuric acid dissociation)
CaCO3+2 H3O+Ca2++H2CO3+2 H2O(calcium carbonate dissolution)
Ca2++SO42-CaSO4(formation of calcium sulfate)
CaSO4+2 H2OCaSO4 · 2 H2O(formation of gypsum)

This reaction chain forms gypsum. [19]

Morphology

Limestone pavement in Dent de Crolles, France Karst Dent-de-Crolle-8.jpg
Limestone pavement in Dent de Crolles, France

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), runnels, limestone pavement (clints and grikes), collectively called karren or lapiez. Medium-sized surface features may include sinkholes or cenotes (closed basins), vertical shafts, foibe (inverted funnel shaped sinkholes), disappearing streams, and reappearing springs. Large-scale features may include limestone pavements, poljes, and karst valleys. Mature karst landscapes, where more bedrock has been removed than remains, may result in karst towers, or haystack/eggbox landscapes. Beneath the surface, complex underground drainage systems (such as karst aquifers) and extensive caves and cavern systems may form.

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. 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 speleothems are formed by deposition of calcium carbonate and other dissolved minerals.

Hydrology

Features typical of well-developed karst terrain KarstterrainUSGS.jpg
Features typical of well-developed karst terrain
A karst spring in the Jura mountains near Ouhans in eastern France at the source of the river Loue SourceDeLaLoue.jpg
A karst spring in the Jura mountains near Ouhans in eastern France at the source of the river Loue

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.

A karst fenster (karst window) occurs when an underground stream emerges onto the surface between layers of rock, 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, usually under a different name (like Ljubljanica, the river of seven names). An example of this is the Popo Agie River in Fremont County, Wyoming. At a site simply 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 800 m (12 mi) down the canyon in a placid pool. A 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.

Water supplies from wells in karst topography may be unsafe, as the water may have run unimpeded from a sinkhole in a cattle pasture, through a cave and to the well, bypassing the normal filtering that occurs in a porous aquifer. Karst formations are cavernous and therefore have high rates of permeability, resulting in reduced opportunity for contaminants to be filtered. Groundwater in karst areas is just as easily polluted as surface streams. Sinkholes have often been used as farmstead or community trash dumps. Overloaded or malfunctioning septic tanks in karst landscapes may dump raw sewage directly into underground channels.

The karst topography also poses difficulties for human inhabitants. Sinkholes can develop gradually as surface openings enlarge, but progressive erosion is frequently unseen until the roof of an underground 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. [20]

Interstratal karst

Interstratal karst is a karstic 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 extensive doline fields developed at Mynydd Llangynidr across a plateau of Twrch Sandstone overlying concealed Carboniferous Limestone. [21]

Kegelkarst

Kegelkarst is a type of tropical karst terrain with numerous cone-like hills, formed by cockpits, mogotes, and poljes 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. [22]

Pseudokarst

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

Karst areas

Lunan Stone Forest, Yunnan, China Yunnanshilin2.jpg
Lunan Stone Forest, Yunnan, China

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. [23] [24]

Mexico hosts important karstic regions in the Yucatán Peninsula and Chiapas. [25]

The South China Karst in the provinces of Guizhou, Guangxi, and Yunnan provinces is a UNESCO World Heritage Site.

The Tham Luang Nang Non karstic cave system in northern Thailand was made famous by the 2018 rescue of a junior football team.

See also

Related Research Articles

Cave Natural underground space large enough for a human to enter

A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word cave can also refer to much smaller openings such as sea caves, rock shelters, and grottos, though strictly speaking a cave is exogene, meaning it is deeper than its opening is wide, and a rock shelter is endogene.

Sinkhole Depression or hole in the ground caused by collapse of the surface into an existing void space

A sinkhole, also known as a cenote, sink, sink-hole, swallet, swallow hole, or doline, is a depression or hole in the ground caused by some form of collapse of the surface layer. Most are caused by karst processes – the chemical dissolution of carbonate rocks or suffosion processes. Sinkholes vary in size from 1 to 600 m both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may form gradually or suddenly, and are found worldwide.

Hạ Long Bay bay

Ha Long Bay is a UNESCO World Heritage Site and popular travel destination in Quang Ninh Province, Vietnam. The name Hạ Long means "descending dragon". Administratively, the bay belongs to Ha Long City, Cam Pha City, and is a part of Van Don District. The bay features thousands of limestone karsts and isles in various shapes and sizes. Ha Long Bay is a center of a larger zone which includes Bai Tu Long Bay to the northeast, and Cat Ba Island to the southwest. These larger zones share a similar geological, geographical, geomorphological, climate, and cultural characters.

Foiba A type of deep natural sinkhole

A foibajama in South Slavic languages scientific and colloquial vocabulary — is a type of deep natural sinkhole, doline, or sink, and is a collapsed portion of bedrock above a void. Sinks may be a sheer vertical opening into a cave, or a shallow depression of many hectares. They are common in the Kras (Carso) region shared by Italy and Slovenia, as well as in a karst of Dinaric Alps in Bosnia and Herzegovina, Montenegro and Croatia.

Altopiano delle Murge mountain

The Altopiano delle Murge is a karst topographic plateau of rectangular shape in southern Italy. Most of it lies within Apulia and corresponds with the sub-region known as Murgia or Le Murge. The plateau lies mainly in the Metropolitan City of Bari and the province of Barletta-Andria-Trani, but extends into the provinces of Brindisi and Taranto to the south; and into Matera in Basilicata to the west. The name is believed to originate from the Latin murex, meaning "sharp stone".

Eramosa Karst

The Eramosa Karst is a provincially significant Earth Science Area of Natural and Scientific Interest in Ontario, Canada, located in Stoney Creek, a constituent community of the City of Hamilton, and immediately south of the Niagara Escarpment.

Karst fenster An unroofed portion of a cavern which reveals part of a subterranean river

Karst fenster is a geomorphic feature formed from the dissolution of carbonate bedrock. In this feature, a spring emerges, then the discharge abruptly disappears into a sinkhole. The word fenster is German for 'window', as these features are windows into the karst landscape.

Ponor

A ponor is a natural opening where surface water enters into underground passages; they may be found in karst landscapes where the geology and the geomorphology is typically dominated by porous limestone rock.

The Nambung River is a river in the Wheatbelt region of Western Australia, 170 kilometres (106 mi) north of Perth. The river drains an area between the towns of Cervantes and Badgingarra. In its lower reaches the Nambung River forms a chain of waterholes in the Nambung Wetlands where it disappears underground into a limestone karst system 5.5 kilometres (3 mi) from the Indian Ocean.

Solutional cave cave formed in soluble rock such as limestone, chalk, dolomite, marble, salt beds or gypsum

A solutional cave or karst cave is a cave usually formed in the soluble rock limestone. It is the most frequently occurring type of cave. It can also form in other rocks, including chalk, dolomite, marble, salt beds, and gypsum.

Škocjan Caves Regional Park is located in the Škocjan Karst, a vast flat landscape that lies at an elevation between 420 and 450 m in the southeast part of the Karst area. Following its independence, the Slovenia committed itself to protecting the Škocjan Caves area; for this reason, it established Škocjan Caves Regional Park and its managing authority, the Škocjan Caves Park Public Service Agency.

Suffosion

Suffosion is one of the two geological processes by which subsidence sinkholes or dolines are formed, the other being due to collapse of an underlying cave or void, with most sinkholes formed by the suffosion process. Suffosion sinkholes are normally associated with karst topography although they may form in other types of rock including chalk, gypsum and basalt. In the karst of the UK's Yorkshire Dales, numerous surface depressions known locally as "shakeholes" are the result of glacial till washing into fissures in the underlying limestone.

Uvala (landform) A local toponym in some regions in Croatia, Bosnia and Herzegovina, Montenegro and Serbia for a closed karst depression

Uvala is originally a local toponym used by people in some regions in Slovenia, Croatia, Bosnia and Herzegovina, Montenegro and Serbia. In geosciences it denotes a closed karst depression, a terrain form usually of elongated or compound structure and of larger size than that of sinkholes (dolines). It is a morphological form frequently found in the “Outer Dinarides” anywhere between Slovenia and Greece. But large closed karst depressions are found on all continents in different landscapes and therefore uvala has become a globally established term, used also to distinguish such depressions from poljes. Definitions of uvalas are often poorly empirically supported. “The coalescence of dolines” is a most frequently found and still dominant explanation. Yet because of the ongoing dissatisfaction with this definition the term ‘uvala’ has often been belittled – occasionally it was even proposed that the term be given up altogether.

Municipality of Mirna Peč Municipality in Slovenia

The Municipality of Mirna Peč is a municipality in southeast Slovenia, located in the traditional region of Lower Carniola. The seat of the municipality, which was established in 1998, is Mirna Peč. With an estimated population of 2,800, the municipality is included in the Southeast Slovenia Statistical Region.

Little Blue Lake Flooded sinkhole dive site in South Australia

Little Blue Lake is a water-filled doline in the Australian state of South Australia located in the state's south-east in the locality of Mount Schank about 20 kilometres (12 mi) south of the municipal seat of Mount Gambier. It is notable locally as a swimming hole and nationally as a cave diving site. It is managed by the District Council of Grant and has been developed as a recreational and tourism venue.

Cedar Sink Sinkhole in Mammoth Cave National Park

Cedar Sink is a vertical-walled large depression, or sinkhole, in the ground, that is located in Edmonson County, Kentucky and contained within and managed by Mammoth Cave National Park. The sinkhole measures 300 feet (91.4 m) from the top sandstone plateau to the bottom of the sink and was caused by collapse of the surface soil. The landscape is karst topography, which means the region is influenced by the dissolution of soluble rocks. Sinkholes, caves, and dolines typically characterize these underground drainage systems. Cedar Sink has a bottom area of about 7 acres (2.8 ha) and has more fertile soil compared to the ridgetops.

Zalomka river in Bosnia and Herzegovina

Zalomka is a karstic river in the southern part of Bosnia and Herzegovina, and one of the largest sinking rivers in the country and the world. It collect its waters from Gatačko Polje.

Karst Living Museum

The Karst Living Museum is a nature trail in Slovenia. Part of the Karst Plateau, the museum is an ecologically-important area with many karst features. It was recognized as Slovenia's best thematic trail in 2017, and the region is a Natura 2000 site.

References

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  23. Austin Peay State University : Harned Bowl work not to blame for new sinkhole, say experts
  24. What is Karst topography and why should you care? - Clarksville, TN Online
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Further reading