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National Geologic Map Database

Geologic Unit: Thermopolis

Usage:

Thermopolis Shale (MT*,WY*)
Thermopolis Shale of Colorado Group (WY)


Subunits:

(alphabetical): [†?]Birdhead Sandstone Member (MT), Cyprian Sandstone Member (MT*), Muddy Sandstone Member (WY*).


Geologic age:

late Early Cretaceous (Albian)*


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

Not designated. Named from Thermopolis, Hot Springs Co., WY (Lupton, 1916).
Reference section: in SW/4 sec. 20, T. 2 S., R. 7 E., Gallatin Co., MT (Roberts, 1972).


AAPG geologic province:

Montana folded belt*
Bighorn basin*
Chadron arch
Denver basin*
Green River basin*
Williston basin*
Snake River basin*
Wind River basin*
Powder River basin*
Central Montana uplift*
Yellowstone province*


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 ([ ]).