Historical:Cora Limestone Member
Elwood Atherton, Charles Collinson, and Jerry A. Lineback
The Cora Limestone Member of the Clore Formation (Swann, 1963, p. 40-41), the lowest member, is named for Cora, Jackson County.
The type section of the Cora Limestone Member is at the mouth of Degonia Creek Hollow (SW SE 16, 8S-5W).
Extent and Thickness
The Cora is 15-45 feet thick.
It varies from dominantly limestone to dominantly shale. In both facies, the Cora is interbedded limestone and shale and locally contains sandstone lenses.
A zone in the Cora Member in which the limestone surfaces are covered with delicate branching bryozoans is the Batostomella nitidula Peak Zone (S. Weller, 1926).
SWANN, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.
WELLER, STUART, 1926, Faunal zones in the standard Mississippian section: Journal of Geology, v. 34, p. 320-335.
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