- Usage in publication:
-
- Sausalito chert*
- Modifications:
-
- Named
- Dominant lithology:
-
- Chert
- AAPG geologic province:
-
- California Coast Ranges province
Summary:
Named as second from lowermost formation in Franciscan Group from town of Sausalito, Marin Co, CA. [First used by Lawson (1902) in table]. Consists of radiolarian chert, prevailingly dull brownish red but includes some rocks of yellow, green, and other colors. Thin films of manganese oxides appear along bedding planes. Is about 900 ft thick. Overlies Cahil sandstone (new); underlies Marin sandstone (new) (both of Franciscan group). Age given as Jurassic(?).
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Sausalito Chert, Memberâ€
- Modifications:
-
- Abandoned
- AAPG geologic province:
-
- California Coast Ranges province
Summary:
Sausalito Chert of Franciscan Group of Lawson (1914), later Sausalito Chert Member of Franciscan Formation, is abandoned because writer was unable to use beds as stratigraphic markers in Franciscan as suggested by Lawson. Franciscan is Jurassic and Cretaceous age based in part on DOUVILLEICERAS sp. (ammonite) (Schlocker and others, 1954).
Source: GNU records (USGS DDS-6; Menlo GNULEX).
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 ([ ]).