- Usage in publication:
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- Rock River Formation*
- Modifications:
-
- Named
- Dominant lithology:
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- Sandstone
- AAPG geologic province:
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- Green River basin
Summary:
Named for exposures in SE1/4 sec 8, SW1/4 sec 9, NW1/4 sec 16, T20N, R76W, 2 mi southeast of Rock River, Albany Co, WY, in Greater Green River basin. Type section measured in S1/2 N1/2 and NE1/4 SE1/4 sec 8, NW1/4 NW1/4 SW1/4 sec 9 and NW1/4 NW1/4 sec 16, T20N, R76W. Known in Laramie basin of Greater Green River basin as the lower (of two) formation of Mesaverde Group. Consists of light-gray to tan, very fine to fine-grained, thin-bedded to massive sandstone. Locally sandstone is shaly and cross bedded. Fossiliferous sandstone concretions in some beds. Is 1,565 ft at type. Overlies Steele Shale; underlies Pine Ridge Sandstone (elevated in rank from member to formation). Has abundant marine fossils. Is of late Campanian age. Correlation with other units of the same Late Cretaceous age shown on Table 1.
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 ([ ]).