Please Note: This is an archived website. It is recommended to search on-line for revised or newer information.
Link to USGS Home Page CGS home USGS home


Find Geologic Maps


Southern California Geology

Links and Resources

Site Contents

Contact Us


Oblique aerial photograph looking west toward San Gorgonio Pass

Oblique aerial photograph looking west toward San Gorgonio Pass. To the south (left) are Peninsular Ranges-type basement rock of the San Jacinto Mountains; to the north (right) are San Gabriel Mountains-type basement rocks of the San Bernardino Mountains that rise above foothills of Tertiary and Quaternary sedimentary materials. Young Quaternary alluvial deposits occupy the center of San Gorgonio Pass; these mainly are derived from easily eroded bedrock to the north of the Pass. Interstate Highway 10 snakes east-west through the lowland between the two mountain masses. Some workers propose that a significant east-trending buried fault must lie concealed beneath alluvial deposits in the center of San Gorgonio Pass in order to account for the steep northern front of the San Jacinto Mountains. Evidence for such a structure is not compelling, however. Photo by J.C. Matti, USGS, December, 1979.

Return to Previous Page

blue line
Southern California Areal Mapping Project logo
SCAMP Home Page
USGS Geology, Minerals, Energy, and Geophysics
California Geological Survey
USGS Home || Search USGS

blue line

  U.S. Department of the Interior, U.S. Geological Survey
Maintainer: WESP team webmaster contact
Privacy Statement || Disclaimer || Accessibility
This site last updated September 3, 2004 (ps)

First Gov