Usage:
Two Medicine Formation of Montana Group (MT*)
Subunits:
Ardmore Bentonite Beds (MT*).
Geologic age:
Late Cretaceous (Campanian)*
Type section, locality, area and/or origin of name:
[Type locality not stated.] Exposed, together with underlying and overlying formations, on Two Medicine River between its mouth and Family Post Office, Blackfeet Indian Reservation, Pondera and Glacier Counties, Montana (Stebinger, 1914).
[Approx. from NW/4 NW/4 sec. 2, T. 31 N., R. 5 W., Abbott Lake 7.5-min quadrangle, to NW/4 NW/4 sec. 2, T. 31 N., R. 9 W., Piegan 7.5-min quadrangle; Lat. 48 deg. 28 min. 50 sec. N., Long. 112 deg. 13 min. 45 sec. W. to Lat. 48 deg. 28 min. 55 sec. N., Long. 112 deg. 44 min. 40 sec. W.]
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 ([ ]).