- Usage in publication:
-
- Lyons Valley Member*
- Modifications:
-
- Named
- Dominant lithology:
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- Siltstone
- Claystone
- AAPG geologic province:
-
- Wind River basin
Summary:
Named as upper member of Popo Agie Formation (rank raised) of Chugwater Group (rank raised). Type section is in SE1/4 sec 13, SW1/4 sec 12, T32N, R99W, Fremont Co, WY in Wind River basin. Is about 60 ft thick at type. Recognized between Lander, Fremont Co to Beaver Creek, Natrona Co. Consists of purple and ocher siltstone, analcime-rich claystone, and analcimolite. Contact with underlying Brynt Draw Member (new) of Popo Agie placed at break in slope that separates hard, gritty, rough surface of Brynt Draw from soft slope of Lyons Valley. Purple and ocher analcime-rich rocks occur throughout. The Brynt Draw and Lyons Valley not separable in Bell Springs-Ferris Mountains area. Unconformably underlies Bell Springs Member (new) of Nugget Sandstone. Of Triassic age. Cross sections.
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 ([ ]).