- Usage in publication:
-
- Crosby breccia [member]
- Modifications:
-
- Named
- Dominant lithology:
-
- Breccia
- AAPG geologic province:
-
- Bighorn basin
Summary:
Named [probably as a member] as part of Wiggins formation for exposures of andesite flows and breccias on southeast flanks of Mt. Crosby, near Kirwin, Park Co, WY in Bighorn basin. No type locality designated. Is characterized by abundance of light greenish-gray, angular rhyolite fragments in addition to angular to subrounded green and purple andesite fragments enclosed in autobrecciated? andesitic matrix. Is limited in extent to the upper Wood River-Greybull River. Is 525 ft thick near Kirwin. Unconformably (angular to erosional) above andesite flows, flow breccias, and tuffs of Wiggins. Overlain by dominantly hornblende-biotite andesite and pyroxene andesite flows, breccias, and tuffs of Wiggins. [Age of member not clearly stated.] Age of Wiggins is late Eocene and Oligocene.
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 ([ ]).