Cora Limestone Member
Lithostratigraphy: Pope Megagroup >>Clore Formation >>Cora Limestone Member
Chronostratigraphy: Paleozoic Erathem >>Mississippian Subsystem >>Chesterian Series >>Elviran Stage
Allostratigraphy: Kaskaskia Sequence
Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.
Elwood Atherton, Charles Collinson, and Jerry A. Lineback
The Cora Limestone Member of the Clore Formation (Swann, 1963, p. 40-41).
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).
The Cora Limestone Member is the lowest member of the Clore Formation.
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.
Well log characteristics
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).
Age and correlation
Environments of deposition
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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