Casper Formation (CO*,WY*)
Darwin Sandstone Member (WY*).
Middle Pennsylvanian to early Permian*
Type area: Casper Mountain, Natrona Co., central WY (Darton, 1908).
Green River basin*
Powder River basin*
Wind River 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 ([ ]).