No current usage?
(†Hay Creek Coal or †Hay Creek Formation (WY) considered abandoned? Uncertain if used by the WY Geol. Survey. Not used by the USGS.)
Early Cretaceous
Not designated. Origin of name not stated by author, but probably named from Hay Creek coal field, Crook Co., WY (Jenney, 1899).
Powder 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 ([ ]).