Usage:
Bighorn Dolomite (ID*,MT*,UT*,WY*)
Bighorn Dolostone (MT*)
Bighorn Limestone (MT*,SD*)
Bighorn Group (MT*,ND*,SD*,WY*)
Subunits:
GROUP STATUS (alphabetical): Red River Formation (MT*,ND*,SD*,WY*), Stonewall Formation (MT,ND), Stony Mountain Formation. (MT*,ND*,SD*,WY*).
FORMATION STATUS (alphabetical): Horseshoe Mountain Member (WY), Lander Sandstone Member (MT,WY), Leigh Member (MT,WY), Steamboat Point Member (WY).
Geologic age:
Middle to Late Ordovician*
Type section, locality, area and/or origin of name:
Named from exposures in Bighorn Mountains, WY (Darton, 1904).
Reference section: on northeast spur of Three Rivers Peak, Gallatin Range, Yellowstone National Park, WY (Ruppel, 1972).
AAPG geologic province:
Bighorn basin*
Green River basin*
Montana folded belt
Powder River basin*
Snake River basin*
Uinta uplift*
Williston basin*
Wind River basin*
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 conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).