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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
http://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htmhttp://www.earlham.edu/~trumary/yucatancave.htm8/3/2019 08 Karst f
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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/Karren8/3/2019 08 Karst f
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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.jpg8/3/2019 08 Karst f
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EX: Popo Agie RiverSinkResurgence/spring
Sink Rise
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Springs
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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.jpg8/3/2019 08 Karst f
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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".
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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.html8/3/2019 08 Karst f
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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