National Geologic Map Database

Geologic Unit: Monterey


Monterey Formation (CA*)
Monterey Shale (CA*)
Monterey Group (CA*-recognized locally in San Francisco region)


GROUP STATUS (alphabetical) --all in CA: Claremont Shale*, Hambre Sandstone*, Oursan Sandstone*, Rodeo Shale*, Sobrante Sandstone*, Tice Shale*.
FORMATION STATUS (alphabetical) --all in CA: Aguajito Shale Member, Altamira Shale Member*, /Antelope Shale Member, Beechers Bay Member, Belridge Diatomite Member*, Buttle Member* or Buttle Diatomite Member, Canyon Del Rey Diatomite Member, Chico Martinez Chert Member, Devilwater Member*, Elk Hills Member* or Elk Hills Shale Member, Gould Shale Member*, Hames Member*, Los Laureles Sandstone Member, Malaga Mudstone Member*, McDonald Shale Member, McLure Member*, Reef Ridge Shale Member, Saltos Member* or Saltos Shale Member, Sandholdt Member*, Twisselmann Sandstone Member, Valmonte Diatomite Member*, Whiterock Bluff Shale Member*, Woodhams Shale Member.

Geologic age:


Type section, locality, area and/or origin of name:

About 2 mi southeast from center of town of Monterey, forming portion of hill 500 to 600 ft. high, which fronts the bay and rises on east side of stage road to San Francisco. This hill is separated from bay by a broad sandy plain and a belt of sand hills along the beach, west-central CA (Blake, 1856).
Hanna in 1928 (AAPG Bull., v. 12, no. 10, p. 969-983) states that locality is on northwest side of long ridge which partly encircles the bay; exposure can be traced from line of Monterey-Salinas Highway to and a little across Monterey-Carmel Highway, a distance of about 4 mi.

AAPG geologic province:

California Coast Ranges province*
Sacramento basin*
San Joaquin basin*
Santa Cruz 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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).