Usage:
Tidwell Member of Morrison Formation (AZ*,CO*,NM*,UT*)
Geologic age:
Late Jurassic (Kimmeridgian)*
Type section, locality, area and/or origin of name:
Type section: in NE/4 SE/4 SE/4 sec. 24, T. 22 S., R. 13 E., Emery Co., UT. Named from Tidwell Bottoms, a marshy area along San Rafael River, Emery Co., UT (Peterson, 1988).
Reference section: on east-facing cliffs of Gunnison River, western Black Canyon, Montrose Co., CO (O'Sullivan, 1992b).
AAPG geologic province:
Black Mesa basin*
Paradox basin*
Piceance basin*
Plateau sedimentary province*
San Juan basin*
San Juan Mountains province*
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 ([ ]).