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Karst and Karst Terranes Word is German form of the Yugoslavian term “Kras” means “bare stony ground” Named after investigating a region near the Adriatic.

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Presentation on theme: "Karst and Karst Terranes Word is German form of the Yugoslavian term “Kras” means “bare stony ground” Named after investigating a region near the Adriatic."— Presentation transcript:

1 Karst and Karst Terranes Word is German form of the Yugoslavian term “Kras” means “bare stony ground” Named after investigating a region near the Adriatic Sea in Yugoslavia In modern Geomorphology the term refers to any landscape formed by dissolution of the underlying bedrock Characterized by distinctive landforms which don’t typically occur in any other circumstance Pseudokarst is the term for karst-like development in non- carbonate lithology that exhibits characteristics similar to karst landscapes, but which lack dissolution as a primary means of landscape formation. Karst and Karst Terranes Word is German form of the Yugoslavian term “Kras” means “bare stony ground” Named after investigating a region near the Adriatic Sea in Yugoslavia In modern Geomorphology the term refers to any landscape formed by dissolution of the underlying bedrock Characterized by distinctive landforms which don’t typically occur in any other circumstance Pseudokarst is the term for karst-like development in non- carbonate lithology that exhibits characteristics similar to karst landscapes, but which lack dissolution as a primary means of landscape formation.

2 Major known Karst regions of the world

3 Factors affecting Karst Solubility of Limestone - percent calcite Climate - Temperature and Moisture Structure of Limestone - joints, fractures, porosity, Mineralogy/lithological content % clastics, % spar vs micrite vs skeletal Vegetation/Non-carbonate Geology - acidity (pH) of groundwater Atmospheric CO 2 - affects solubility of Carbonates Factors affecting Karst Solubility of Limestone - percent calcite Climate - Temperature and Moisture Structure of Limestone - joints, fractures, porosity, Mineralogy/lithological content % clastics, % spar vs micrite vs skeletal Vegetation/Non-carbonate Geology - acidity (pH) of groundwater Atmospheric CO 2 - affects solubility of Carbonates

4 Dissolution of Carbonates CaCO 3 dissociates into its constituent ionic components in water CaCO 3 Ca 2+ + CO 3 2- (Limestone) CaMg(CO 3 ) 2 Ca 2+ + Mg CO 3 2- (Dolomite) However, dissolution occurs more frequently as a result of a reaction with carbonic acid formed with carbon dioxide CaCO 3 + H 2 O + 2CO 2 Ca HCO 3 - CaMg(CO 3 ) 2 + 2H CO 2 Ca 2+ + Mg HCO 3 -

5 Karst Collapse Landforms Sinkhole - a.k.a. Doline comes in a variety of shapes most often funnel shaped forms as material above a cavity becomes too thin to support the weight sometimes filled with colluvium from edges of feature can form circular lakes often entrances to caves are found in sinkholes related to formation of feature Compound sinks - a.k.a. Uvalas several sinkholes coalesce to form a larger structure these may be quite large (a kilometer) Occasionally, uvalas are floored with alluvium derived from subterranean streams called a karst gulf or a polje Karst Collapse Landforms Sinkhole - a.k.a. Doline comes in a variety of shapes most often funnel shaped forms as material above a cavity becomes too thin to support the weight sometimes filled with colluvium from edges of feature can form circular lakes often entrances to caves are found in sinkholes related to formation of feature Compound sinks - a.k.a. Uvalas several sinkholes coalesce to form a larger structure these may be quite large (a kilometer) Occasionally, uvalas are floored with alluvium derived from subterranean streams called a karst gulf or a polje

6 A Sinkhole (cockpit) in Central America

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9 Karst features in Florida

10 Karst terrane in Australia - a karren plain with blind valleys and numerous sinkholes Karst terrane in Australia - a karren plain with blind valleys and numerous sinkholes

11 A doline (sinkhole)in Winterpark, FL

12 A 300 ft deep sinkhole in Guatemala

13 “The Blue Hole” is an underwater sinkhole, 1000 ft across & 400 ft deep

14 Karst Landforms- stream features chaotic or deranged drainage patterns few, if any, through flowing streams in karst regions often exhibit what are called blind valleys e.g., Lost river, tributaries and other surface streams in the Mitchell plain streams disappear into a swallow hole called a ponor, a swallet, or a sink -Tolliver Swallow; Stein Swallow often reappear as a karst spring or a groundwater rise -Orangeville rise; -Wesley Chapel Gulf rise Karst Landforms- stream features chaotic or deranged drainage patterns few, if any, through flowing streams in karst regions often exhibit what are called blind valleys e.g., Lost river, tributaries and other surface streams in the Mitchell plain streams disappear into a swallow hole called a ponor, a swallet, or a sink -Tolliver Swallow; Stein Swallow often reappear as a karst spring or a groundwater rise -Orangeville rise; -Wesley Chapel Gulf rise

15 Drainage in a Karst region in Europe -flooded and backed up into the overflow channels - polje Drainage in a Karst region in Europe -flooded and backed up into the overflow channels - polje

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17 A rise of a subterranean stream

18 Solution pan on a karren in the southwestern USA

19 Karst landforms- denudation often large tracts of limestone karst terranes are devoid of unconsolidated material these areas are called Karrens Often have solution enhanced vertical fracture and joints sets they can be filled with debris from dissolution or devoid of residuum known as grikes, kluftkarren or solution grooves Karst landforms- denudation often large tracts of limestone karst terranes are devoid of unconsolidated material these areas are called Karrens Often have solution enhanced vertical fracture and joints sets they can be filled with debris from dissolution or devoid of residuum known as grikes, kluftkarren or solution grooves

20 Grikes or Kluftkarren - a.k.a. solution enhanced vertical fractures. the grikes divide the surface into distinct pieces referred to as Clints Grikes or Kluftkarren - a.k.a. solution enhanced vertical fractures. the grikes divide the surface into distinct pieces referred to as Clints

21 Closeup of a Karren with grikes

22 Soils developed in karst terranes commonly develop a thick red cap called terra rosa origins are debated and may be site specific composed of clay rich in iron sesquioxide minerals Commonly thought of as leftovers after intense leaching of surface rock May also have contribution by loess and other wind transported sediments Less commonly develop another type of soil that is thin, very permeable and porous called rendzinas allow extreme infiltration loamy with pieces of limestone residuum

23 terra rosa soil loess

24 Karren with Grikes in Ireland

25 Grikes or cutters, filled with terra rosa, shown in cross-section in a roadcut

26 Karst terranes in high humidity regions forms a variety of spectacular landforms Towers, Mounds and Cockpits -erosional remnants of thick sequences of limestone that have been greatly degraded Karst terranes in high humidity regions forms a variety of spectacular landforms Towers, Mounds and Cockpits -erosional remnants of thick sequences of limestone that have been greatly degraded

27 Cockpit karst region in Jamaica

28 Tower karst in S.E. China

29 Tower Karst in S.E. China

30 Eastern Illinois basin strata and karst development

31 Mitchell Plain and Chester Escarpment

32 Sinking stream in karst area of Kentucky

33 Sinkhole plain in the Kentucky equivalent of the Mitchell Plain


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