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National Geologic Map Database

Geologic Unit: Cochrane

Usage:

Cochrane Formation of Hunton Group (OK)
Cochrane Member of Chimneyhill Limestone (OK)
Cochrane Formation of /Chimneyhill subgroup [informal] of Hunton Group (OK)

["Subgroup" not recognized as a formal stratigraphic rank term (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). Chimneyhill subgroup considered informal and should not be capitalized.]


Geologic age:

early Silurian (Llandovery)


Type section, locality, area and/or origin of name:

Not designated. Origin of name not stated by author (Maxwell, 1936).
Type section: in SE/4 sec. 5, T. 2 N., R. 6 E. [Pontotoc Co., OK]. Well exposed along banks of small tributary entering Chimneyhill Creek (Amsden, 1957).


AAPG geologic province:

Arkoma basin
South Oklahoma folded belt


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

Asterisk (*) indicates published by U.S. Geological Survey authors.

"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 conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).