Usage:
No current usage.
(†Yankee Fork Rhyolite Member of Challis Volcanics (ID) abandoned.)
Geologic age:
Tertiary(?)
Oligocene, late(?)
Type section, locality, area and/or origin of name:
Not designated. Named from exposures in ridges encircling head of Yankee Fork, Casto quadrangle, Custer Co., ID (Ross, 1934).
AAPG geologic province:
Idaho 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 ([ ]).