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 carbonate 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.

Major known Karst regions of the world

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 CO2 - affects solubility of Carbonates

Dissolution of Carbonates CaCO3 dissociates into its constituent ionic components in water CaCO3 Ca2+ + CO32- (Limestone) CaMg(CO3)2 Ca2+ + Mg2+ + 2CO32- (Dolomite) However, dissolution occurs more frequently as a result of a reaction with carbonic acid formed with carbon dioxide CaCO3 + H2O + 2CO2 Ca2+ + 2HCO3- CaMg(CO3)2 + 2H20 + 2CO2 Ca2+ + Mg2+ + 4HCO3-

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

A Sinkhole (cockpit) in Central America

Karst features in Florida

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

A doline (sinkhole)in Winterpark, FL

A 300 ft deep sinkhole in Guatemala

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

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

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

A rise of a subterranean stream

Solution pan on a karren in the southwestern USA

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

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

Closeup of a Karren with grikes (note the plants indicating sediment in the joints

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

loess terra rosa soil

Karren with Grikes in Ireland

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

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

Cockpit karst region in Jamaica

Tower karst in S.E. China

Tower Karst in S.E. China

Eastern Illinois basin strata and karst development Mitchell plain

Mitchell Plain and Chester Escarpment

Sinking stream in karst area of Kentucky

Sinkhole plain in the Kentucky equivalent of the Mitchell Plain