Usage:
Hell Creek Formation (MT*,ND*,SD*,UT,WY)
Hell Creek Formation of Montana Group (MT)
Subunits:
FORMATION STATUS (alphabetical): Bacon Creek Member (MT,ND), Breien Member (ND), Bull Creek sand [informal, unranked] (SD), Crowghost Member (ND), Fort Rice Member (ND), Huff Member (MT,ND), Little Beaver Creek Member (ND), Marmarth Member (ND), Pretty Butte Member (MT,ND).
Geologic age:
Late Cretaceous*; locally early Tertiary (Paleocene)*
Type section, locality, area and/or origin of name:
Lectostratotype (composite): in Ried Coulee and East Ried Coulee, in N/2 sec. 29, T. 21 N., R. 38 W., from about Lat. 47.55122 deg. N., Long. 106.86217 deg. W., northwestward to Lat. 47.56908 deg. N., Long. 106.89648 deg. W., Maloney Hill and Buffalo Hill quadrangles, Garfield Co., eastern MT (Hartman and others, 2014).
Named from exposures on Hell Creek and nearby tributaries of Missouri River, [Garfield Co.], MT (Brown, 1907).
AAPG geologic province:
Central Montana uplift*
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 ([ ]).