Open-File Report 94-231

Preliminary Quaternary Geologic Maps of Santa Clara Valley, Santa Clara, Alameda, and San Mateo Counties, California: A Digital Database

By E.J. Helley, R.W. Graymer, G.A. Phelps, P.K. Showalter, and C.M. Wentworth

Geology by E.J. Helley

Digital database compiled By R.W. Graymer, G.A. Phelps, P.K. Showalter, and C.M. Wentworth

thumbnail view of map

View the database explanation pamphlet as an unformatted, text-only file: scc_q1.ReadMe.txt (7 KB)


Digital databases are available for GIS users in ARC/INFO 6.x COVERAGE format. Those who download digital data should also download the descriptive pamphlet.

scgeo.pdf is a PDF file containing detailed unit descriptions and geological information. A copy of this information is also contained within the compressed files below as an ASCII file.

The data have been archived using tar, then compressed with UNIX compression. File sizes (in parentheses) are for the compressed download file, followed by the size of the file when uncompressed.

To download the geologic map data packaged with the PostScript plotfile, select the following:


A plotfile is available for those who wish to produce a paper copy of the map prepared from the digital data. This map has been edited to conform as much as possible to standard U.S. Geological Survey format for geologic maps. The plotfile is in both PostScript and PDF formats. Note that this plotfile is formatted to plot on 36 inch wide large format color plotter. Those who download plotfiles should also download the descriptive pamphlet.

To download the plotfile in PostScript format, select the following:

To download the plotfile in PDF format (not compressed), select the following:

Download a shaded-relief image of Santa Clara County, CA: sccoshd.tiff (2.4 MB)

button-sized photo of Golden Gate Bridge

For more information on the geology
of the San Francisco Bay region:
Visit the sfgeo website

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Maintained by: Michael Diggles
Updated: October 11, 2005 (mfd)