- Usage in publication:
-
- Little Bighorn Member*
- Modifications:
-
- Named
- Dominant lithology:
-
- Dolomite
- Limestone
- AAPG geologic province:
-
- Powder River basin
Summary:
Named a member of the Madison Limestone for exposures in Little Bighorn Canyon in NW1/4 sec 30, T58N, R89W, Sheridan Co., WY. Type section designated in NE1/4 sec 27, T57N, R87W in the Powder River basin. Also recognized in the subsurface of the Bighorn, Wind River, and Powder River basins. Consists of 3 to 48 m of thick-bedded, fine- to medium-crystalline, crinoidal dolomite and dolomitic limestone. Rests conformably on the Cottonwood Canyon Member at most localities, but where Cottonwood Canyon is absent it may rest on Devonian Jefferson Dolomite, Ordovician Bighorn Dolomite, or Ordovician and Cambrian Gallatin Limestone. Is conformably overlain by Woodhurst Member of Madison. Is fossiliferous (conodonts, brachiopods, corals). Age of Kinderhookian or Early Mississippian as determined by brachiopods.
Source: GNU records (USGS DDS-6; Denver GNULEX).
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 ([ ]).