- Usage in publication:
-
- West Fork Formation*
- Modifications:
-
- Named
- Dominant lithology:
-
- Siltite
- Limestone
- AAPG geologic province:
-
- Idaho Mountains province
Summary:
Unit is named the West Fork Formation of the Lemhi Group. Consists of mostly thick-bedded to massive, cross-laminated, ripple-marked, medium to dark greenish-gray siltite, with lenticular algal limestone. Has blocky fracture. Thickness is 460 m. Gradationally overlies the Inyo Creek Formation; gradationally underlies the Big Creek Formation. Age is Precambrian Y. (B1520)
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- West Fork Formation*
- Modifications:
-
- Age modified
- AAPG geologic province:
-
- Idaho Mountains province
Summary:
Age of the West Fork Formation is revised from Precambrian Y to Proterozoic Y.
Source: GNU records (USGS DDS-6; Menlo 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 ([ ]).