No current usage.
(†Beaver Creek Chalky Member of Niobrara Formation (MT*,WY*) is same as Niobrara Formation. See Niobrara.)
Late Cretaceous*
Named from exposures along Beaver Creek, in T. 46 N., R. 64 W., Weston Co., northeastern WY (Rubey, 1931).
Powder River basin*
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 ([ ]).