No current usage.
(†Duchesnean age*, a provincial North American land mammal age (NALMA), considered same as Orelian. See Orellan.)
early Oligocene (Orellan NALMA)
Not designated. Name based on Duchesne River Formation of northeastern UT (Wood and others, 1941).
Uinta 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 ([ ]).