Usage:
No current usage.
(†Twelvemile Canyon Member of Arapien Shale (UT) is same as Arapien Shale. See Arapien.)
Geologic age:
Jurassic, Middle
Bajocian
Bathonian
Callovian, early
Type section, locality, area and/or origin of name:
Not designated. Named from outcrops in valley of Twelvemile Creek, Sanpete Co., UT (Spieker, 1946).
AAPG geologic province:
Wasatch uplift
Great Basin 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 ([ ]).