Usage:
Sonoma Volcanics (CA*)
Subunits:
St. Helena Rhyolite Member (CA*).
Geologic age:
Pliocene*
Miocene*
Type section, locality, area and/or origin of name:
Named from typical exposures on west flanks of Sonoma Mountains, north of San Francisco Bay region, Sonoma Co., northern CA (Dickerson, 1922).
AAPG geologic province:
Northern Coast Range 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 ([ ]).