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National Geologic Map Database

Geologic Unit: Bear Gulch

Usage:

Bear Gulch Member of Tyler Formation of Amsden Group (MT*)
Bear Gulch Member of Tyler Formation (ND*)
Bear Gulch Limestone Member of Heath Formation of Big Snowy Group (MT-recognized locally in Fergus Co.)


Geologic age:

Late Mississippian (Chesterian)*


Type section, locality, area and/or origin of name:

Type locality: along Bear Creek, in sec. 21, T. 14 N., R. 21 E., [approx. Lat. 46 deg. 57 min. 15 sec. N., Long. 109 deg. 03 min. 30 sec. W.], Forestgrove 7.5-min quadrangle, Fergus Co., central MT (Norton, 1956; Maughan, 1984).
Named from exposures in Bear Gulch [Bear Creek, in T. 14 N., R. 21 E.], Fergus Co., central MT; composite section in secs. 32 and 33, T. 14 N., R. 21 E., south of Forestgrove (Norton, 1956). [Called Bear Creek on USGS Forestgrove 7.5-min quadrangle (Maughan, 1984).]


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