Usage:
Ardmore Bentonite Beds of Mitten Member of Pierre Shale (MT*,SD*,WY*-notably in Powder River and Williston basins)
Ardmore Bentonite Bed of Steele Shale (MT*,WY*-notably in western Powder River basin)
Ardmore Bentonite Beds of Claggett Shale (MT*-notably in south-central part)
Ardmore Bentonite Beds of Cody Shale (WY*-notably in northern Bighorn and Powder River basins)
Ardmore Bentonite Beds of Cokedale Formation (MT*-notably in Livingston and Crazy Mountains)
Ardmore Bentonite Beds of Mesaverde Formation (WY*-notably in southern Bighorn basin)
Ardmore Bentonite Beds of Pembina Member of Pierre Shale (ND*)
Ardmore Bentonite Beds of Pierre Shale (MT,NE)
Ardmore Bentonite Beds of Sharon Springs Member of Pierre Shale (CO*,SD*,WY*)
Ardmore Bentonite Beds of Two Medicine Formation (MT*-notably in northwestern part)
[Preoccupied. Name previously applied to Pennsylvanian Ardmore Limestone by Gordon (1893) in MO.]
Geologic age:
Late Cretaceous*
Type section, locality, area and/or origin of name:
Named from exposures near Ardmore, [in northwest part of T. 12 S., R. 4 E.], Fall River Co., southwestern SD (Spivey, 1940).
AAPG geologic province:
Denver basin*
Powder River basin*
Bighorn basin*
Chadron arch*
Williston basin*
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 ([ ]).