Historical:Cedar Bluff Limestone Group

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Handbook of Illinois Stratigraphy
Series Bulletin 95
Author H. B. Willman, Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, Jack A. Simon
Date 1975
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Lithostratigraphy: Pope Megagroup >>Cedar Bluff Limestone Group
Chronostratigraphy: Paleozoic Erathem >>Mississippian Subsystem >>Valmeyeran Series >>Genevievian Stage
Allostratigraphy: Kaskaskia Sequence


Elwood Atherton, Charles Collinson, and Jerry A. Lineback

Name Origin

The Cedar Bluff Limestone Group (Swann, 1963, p. 63) is named for the quarry of the Cedar Bluff Limestone Company, formerly the Ohara quarry, southeast of Princeton, Caldwell County, Kentucky (S1/2 21-H-20). It was originally called the Ohara Limestone, but the name Ohara is widely used for the Karnak Member of the Ste. Genevieve in the subsurface.

Extent and Thickness

It occurs in southeastern Illinois and is exposed in Hardin County.


The Cedar Bluff Limestone Group consists of the Downeys Bluff, Yankeetown, and Renault Formations in areas where these formations are dominantly limestone (fig. M-25).

Stratigraphic Position

The Valmeyeran-Chesterian contact falls within the Cedar Bluff Group at the top of the Levias Limestone Member of the Renault Formation.


SWANN, D. H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks of Illinois: Illinois State Geological Survey Report of Investigations 216, 91 p.

ISGS Codes

Stratigraphic Code Geo Unit Designation