- Usage in publication:
-
- Nefsy shale member*
- Modifications:
-
- Named
- Dominant lithology:
-
- Shale
- AAPG geologic province:
-
- Powder River basin
Summary:
Named as the middle member of five members of the Graneros shale (also called formation) for the townsite of Nefsy at Osage, Weston Co, WY in the Powder River basin. No type locality designated. Overlies Newcastle sandstone member of Graneros. Underlies Mowry shale member of Graneros. Inferred to be locally present beneath the Mowry. Consists of 25 to 50 ft of dark, soft shale with interbedded lenses of sandy shale. Differentiated from the underlying Newcastle by absence of hard sandstone layers. Differentiated from the overlying Mowry by its characteristic sticky mud. Of Late Cretaceous age. Stratigraphic table.
Source: GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Nefsy shale member*†
- Modifications:
-
- Abandoned
Summary:
Name abandoned. Regarded as a basal, undifferentiated part of the Mowry siliceous shale member of the Graneros shale on the west side of the Black Hills in the Powder River and Williston basins.
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 ([ ]).