Usage:
Horsethief Formation (MT)
Horsethief Sandstone of Montana Group (MT*)
Geologic age:
Late Cretaceous (Campanian to Maastrichtian)*
Type section, locality, area and/or origin of name:
Horsethief Ridge, [Buffalo Lake 7.5-min quadrangle], Blackfeet Indian Reservation, Glacier Co., MT. Named from Horsethief Ridge [Lat. 48 deg. 47 min. 10 sec. N., Long. 112 deg. 42 min. 11 sec. W.] (Stebinger, 1914).
AAPG geologic province:
Montana folded belt*
Sweetgrass arch*
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 ([ ]).