Historical:Bankston Fork Limestone Member
Lithostratigraphy: Kewanee Group >>Carbondale Formation >>Bankston Fork Limestone Member
Chronostratigraphy: Paleozoic Erathem >>Pennsylvanian Subsystem >>Desmoinesian Series
Allostratigraphy: Absaroka Sequence
M. E. Hopkins and J. A. Simon
The Bankston Fork Limestone Member of the Carbondale Formation (Cady, 1926, p. 261-262) is named for Bankston Creek in Saline County.
The type section consists of outcrops along the south side of Bankston Creek (NE NW 19, 9S-5E).
The Bankston Fork correlates with the Universal Limestone Member of Indiana and is present in parts of western Kentucky, where it locally is as much as 8 feet thick.
Extent and Thickness
It occurs in southwestern, central, eastern, and southeastern Illinois, where it is commonly several feet thick but seldom over 6 feet. It does not occur west of the Illinois River or in northern Illinois. It commonly is not present over the thick portions of the Anvil Rock Sandstone.
The Bankston Fork is a fine-grained, argillaceous, thick-bedded limestone that is dolomitic in places (fig. P-3B). It is commonly nodular in the upper and lower portions and is generally divided into two benches by a greenish gray shale several inches thick.
It is sparsely fossiliferous, its open-marine fauna dominated by brachiopods, fusulinids, and a few crinoids.
CADY, G. H., 1926, Areal geology of Saline County: Illinois Academy of Science Transactions, v. 19, p. 250-272.
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