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Karst Cvijic (1893) - krs [karst] rocky, bleak

Dissolution, changing water tablelevels, subsidence

Karst : distinctive landforms due tohigh rock solubility, which causessecondary porosity and subsidence

Usually in humid regions.Karst plain, central KY

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Water table followstopography

Changes depth withchanges in

precipitation

Groundwater

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Carbonate Geochemistry

Calcite, water, and air CO 2 pH ~ 8.4CO 2 in air dissolved in cloud droplets

Falls as precipitation Very slow dissolution

Calcite, water, and Humic Acid; pH ~ 4-7 Precip. soaks though O and A horizons, adds plant acids

CaCO 3 (s) + 2H + (aq) Ca ++ (aq) + CO 2 (g) + H 2OTemp: Cold water contains more CO2 CO2 + H2O = > H2CO3 => H+ + HCO3-Pressure: deeper H2O , more CO2 absorbed, more aggressiveMixing can result in undersaturated H2O

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Geologic work of groundwater

Karst topography Landscapes that have been shaped by the

dissolving power of groundwater on limestone Some common features include

Irregular terrain Dolines: Sinkholes or sinks (formed by

groundwater slowly dissolving the bedrock often accompanied by collapse

Disappearing (aka sinking) streams

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Karst Topography

Rocks are dissolved bywater: surface water orgroundwater.

Carbonates, limestone, anddolostone are dissolved byacidic water.

Evaporites, rock salt, andgypsum are dissolved bywater.

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Sinkholes Groundwater dissolves

soluble rock, creatingfractures and caves.

Dissolving continues toform larger caves andfractures.

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Dolines (Sinkholes, Cenotes )

Collapse sinkholes formwhen water level drops

Solution sinkholes duedissolution at surface

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Winter Park sinkhole (1981)

100 m across One day Due to water

table lowering Now an urban

lake.

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Cenotes Yucatan, Florida

Flooded anddissolved duringinterglacial time

Broke duringglaciations As the sea level

dropped during activeglaciation, the water

table also dropped,leading to the drainageof caverns that werepreviously filled withwater. This caused theceilings of the caves to

collapse

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KarstLandscapes

Cockpit karst

Arecibo Radio Astronomy Observatory, Puerto Rico

Cockpit karst is a form of karst in whichthe residual hills are chieflyhemispheroidal and surround closed,lobed, depressions known as dolines or"cockpits" each of which is drained to

the aquifer by one or more sinkholes.

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More terminology

Disappearing streams Sinks => springs

Dissolution: linear Doline: Polje Clint and grike, Karren Solution Valley

Copyright Jelena Calic-Ljubojevic 2002

Karren the micro-solutional feature that forms on exposed limestone surfaces, favoured by pure, homogeneouslimestone with low primary permeability and well developed, widely spaced joints.

Karren

http://en.wikipedia.org/wiki/Karrenhttp://en.wikipedia.org/wiki/Karrenhttp://en.wikipedia.org/wiki/Karrenhttp://en.wikipedia.org/wiki/Karrenhttp://en.wikipedia.org/wiki/Karrenhttp://en.wikipedia.org/wiki/Karrenhttp://en.wikipedia.org/wiki/Karrenhttp://en.wikipedia.org/wiki/Karrenhttp://en.wikipedia.org/wiki/Karren

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Coleridge "Xanadu"

Sinks

Exit as spring or rise

Disappearing Streams

http://upload.wikimedia.org/wikipedia/commons/8/82/Wyoming_Sinks_Canyon_3.jpghttp://upload.wikimedia.org/wikipedia/commons/7/79/Wyoming_Sinks_Canyon_2.jpg

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EX: Popo Agie RiverSinkResurgence/spring

Sink Rise

http://upload.wikimedia.org/wikipedia/commons/7/79/Wyoming_Sinks_Canyon_2.jpghttp://upload.wikimedia.org/wikipedia/commons/8/82/Wyoming_Sinks_Canyon_3.jpghttp://upload.wikimedia.org/wikipedia/commons/8/82/Wyoming_Sinks_Canyon_3.jpghttp://upload.wikimedia.org/wikipedia/commons/7/79/Wyoming_Sinks_Canyon_2.jpg

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Springs

http://upload.wikimedia.org/wikipedia/commons/8/82/Wyoming_Sinks_Canyon_3.jpg

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Polje A polje is a large flat plain in karst territory, often

structurally controlled

Copyright Jelena Calic-Ljubojevic 2002

http://upload.wikimedia.org/wikipedia/commons/8/82/Wyoming_Sinks_Canyon_3.jpghttp://upload.wikimedia.org/wikipedia/commons/8/82/Wyoming_Sinks_Canyon_3.jpghttp://upload.wikimedia.org/wikipedia/commons/8/82/Wyoming_Sinks_Canyon_3.jpghttp://upload.wikimedia.org/wikipedia/commons/8/82/Wyoming_Sinks_Canyon_3.jpghttp://upload.wikimedia.org/wikipedia/commons/8/82/Wyoming_Sinks_Canyon_3.jpg

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Exposed Clint and Grike

Corrosive drainage along joints and cracks in the limestone can produce slabscalled "clints" isolated b dee fissures called " rikes".

http://upload.wikimedia.org/wikipedia/commons/8/82/Wyoming_Sinks_Canyon_3.jpghttp://en.wikipedia.org/wiki/Limestone_pavementhttp://en.wikipedia.org/wiki/Limestone_pavementhttp://en.wikipedia.org/wiki/Limestone_pavementhttp://en.wikipedia.org/wiki/Limestone_pavement

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http://www2c.airnet.ne.jp/kawa/anagly2/07okinawa_a/20070403ae.html

Water frequently gains access via joints

http://www2c.airnet.ne.jp/kawa/anagly2/07okinawa_a/20070403ae.htmlhttp://www2c.airnet.ne.jp/kawa/anagly2/07okinawa_a/20070403ae.html

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Karst Topography Summary

Groundwater level drops, leaving

behind caves , sinkholes disappearing streams

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Tower Karst Tower karst is created

in highly eroded karstregions.

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Thermokarst

Soils containing water expand when frozen,moving the soil upward.

Frost heaving

Cold regions, permafrost.

Winter heaving and summerthawing => uneven soil

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Cave Deposits - Speleothems Cave systems are

formed whendissolution producesa series of caves.

Related to fluctuatinggroundwater table.

Groundwater

seepage causesstalagmites,stalactites.

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Caves form above,at, and below the

GWT

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CAVES are natural underground cavities.Form very slowly.Begin to form first just below the surface of the

water table in the zone of saturation.Become dry when water table goes below the cave

horizon.

CO 2 bubbles out from groundwater. Allows precipitation of calcite. Deposits called SPELEOTHEMS. Composed of travertine (calcite deposited in caves).

STALACTITES - hang from cave ceilingsSTALAGMITES - accumulate on cave floors.When joined together they form COLUMNS.Growth is very slow