Usage:
Logtown Ridge Formation (CA*)
Subunits:
(alphabetical) all in CA*: Goat Hill Member, New Chicago Member, Pokerville Member, Rabbit Flat Member.
Geologic age:
Jurassic, Middle*
Jurassic, Late*
Type section, locality, area and/or origin of name:
At northern type section of †Amador Group [later abandoned]; extends west from Huse Bridge on Highway 49 on Cosumnes River to about 7,400 feet southwest of bridge, El Dorado and Amador Cos., CA. Origin of name not stated by author, but probably named from Logtown Ridge, Lat. 38 deg. 36 min. 59 sec. N., Long. 120 deg. 51 min. 24 sec. W. (Taliaferro, 1943; Clark, 1964).
AAPG geologic province:
Sierra Nevada 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 ([ ]).