Usage:
Tuscan Formation (CA*)
Subunits:
(alphabetical) --all in CA*: Ishi Tuff Member, Nomlaki Tuff Member.
Geologic age:
late Tertiary (Pliocene)*
Type section, locality, area and/or origin of name:
Named from exposures at or near Tuscan Springs, [northwest of Red Bluff, approx. Lat. 40 deg. 14 min. 25 sec. N., Long. 122 deg. 06 min. 41 sec. W., Tehama Co.], Lassen Peak quadrangle, northern CA (US geologic names lexicons, USGS Bull. 896, 1200).
AAPG geologic province:
Klamath Mountains province*
Sacramento basin*
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 ([ ]).