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National Geologic Map Database

Geologic Unit: Alhambra

Usage:

Alhambra Formation (CA)


Subunits:

(alphabetical) --all in CA: Castro Shale Member, Pereira Shale Member, Roop Sandstone Member.


Geologic age:

early Tertiary (Eocene)


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

Type section: west limb of Pacheco syncline in Santa Fe cuts east of east portal of Muir Tunnel near Martinez, Contra Costa Co., west-central CA (Weaver, 1953).


AAPG geologic 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 ([ ]).