The Mitchell Plain is a

karst 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. It has also been documented for more weathering-resistant ro ...

area in

Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...

of relatively low relief. The extensive underlying cave system developed in Mississippian age

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

bedrock. Surface drainage is rare due to most streams in the area disappearing into caves or joints within the rock. The limestone is a vestige of an early shallow

craton A craton (, , or ; from grc-gre, κράτος "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and ...

ic sea that covered what would become Indiana, while the North-South linearity of the region is left over from the Cincinnati Uplift, sloping the rock layers from a high in the East sloping downward towards

Cairo, Illinois Cairo ( ) is the southernmost city in Illinois and the county seat of Alexander County. The city is located at the confluence of the Ohio and Mississippi rivers. Fort Defiance, a Civil War camp, was built here in 1862 by Union General Ulysses ...

. The Mitchell Plain is bound by the older rocks of

Norman Upland The Norman Upland of southern Indiana comprises hilly terrain caused by the outcropping of sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20&nda ...

on the East and the younger rocks of Crawford Upland on the West.

References

Karst fields Landforms of Indiana Limestone formations of the United States Geologic formations of Indiana Mississippian United States {{US-geology-stub