Audio Tours of Mount Diablo
Experience an Audio Tour Here
The tours feature lively interviews and music with the rush of wind and the chirps, howls, and growls of wildlife, all downloadable to an audio video media player

Wildflower Identification Guide

calochortus pulchellus logo mjw

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Geologic Map


Quarternary - surficial deposits
Jurassic/Cretaceous - dark
greenish-gray shale sandstone
interbeds (Knoxville Formation)
Thrust Fault
Quarternary - landslide deposits Jurassic/Cretaceous - melange
(Franciscian Complex)
Thrust Fault - inferred
Miocene/Pliocene - non-marine
sandstone, siltstone, and
Jurassic - chert and basalt with some graywacke and shale
(Franciscan Complex)
Miocene - marine fossiliferous
sandstone and shale
Jurassic - basalt and diabase
(Coast Range Ophiolite)
Fault - Inferred
Miocene - silicic intrusive rocks Jurassic - serpentinite (Coast Range Ophiolite) Roads
Eocene - massive pebbly
sandstone with shale
Silica carbonate rock (altered serpentinite) Streams
Cretaceous - shale, siltstone, and sandstone (Great Valley Sequence)
Data Source Preliminary Geologic Map Emphazing Bedrock Formations in Contra Costa County, California. Compiled by R.W. Graymer, D.L. Jones, and E.E. Brabb U.S. Geological Survey Open-File Report 94-622 Arc/Info Data Files

Simplified with minor modifications by Roi Peers and Craig Lyon, September 1996.

Geologic Information Systems Map by Eric R. Sheehan, Martinez, California.