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National Geologic Map Database
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  • Usage in publication:
    • Cedar Bluff Group
  • Modifications:
    • Named
  • Dominant lithology:
    • Limestone
  • AAPG geologic province:
    • Illinois basin
Publication:

Swann, D.H., 1963, Classification of Genevievian and Chesterian (Late Mississippian) rocks in Illinois: Illinois Geological Survey Report of Investigations, no. 216, 91 p.


Summary:

Named as a group within the Mammoth Caves Megagroup. Proposed for Downeys Bluff, Yankeetown, and Renault Formations where the formations are dominantly limestone. Name is exact objective synonym of Ohara. Reinstatement of Ohara in its original meaning would cause confusion because Ohara now has widespread informal use in subsurface of deeper part of basin for an earlier unit (Karnak Member of Ste. Genevieve). Lies between Aux Vases and Bethel Sandstone. Age is Late Mississippian.

Source: GNU records (USGS DDS-6; Reston GNULEX).


For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).

Slash (/) indicates name does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).