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National Geologic Map Database

Geologic Unit: Two Medicine

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 usage by the U.S. Geological Survey. Other usages by state geological surveys.

"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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).