DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY


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

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



Open - File Report 94-231


This report is preliminary and has not been reviewed for conformity with U.S.
Geological Survey editorial standards or with the North American Stratigraphic 
Code.  Any use of trade, product, or firm names is for descriptive purposes only
and does not imply endorsement by the U.S. Government.

This database, identified as "Preliminary Quaternary geologic maps of Santa 
Clara Valley, Santa Clara, Alameda, and San Mateo Counties, California:  A 
digital database," has been approved for release and publication by the Director
of the USGS.  Although this database has been subjected to rigorous review and 
is substantially complete, the USGS reserves the right to revise the data 
pursuant to further analysis and review.  Furthermore, it is released on 
condition that neither the USGS nor the United States Government may be held 
liable for any damages resulting from its authorized or unauthorized use.



1994



Introduction

This digital map database, which is compiled from previously unpublished and 
open-filed U.S. Geol. Survey reports (Wesling and Helley, 1989), represents the 
general distribution and identity of Quaternary deposits in eight 7.5 minute 
quadrangles in the southern San Francisco Bay region, California.  Together with
the accompanying text file (scgeo.txt), it provides current information on the 
Quaternary geology of the area covered.  The database delineates map units that 
are identified by general age and lithology following the compilation sources. 
One bedrock unit, the Santa Clara formation, is differentiated but the other 
bedrock units are combined and are not identified.  More specific information 
about the units may be available in the original Open-file reports.  The scale 
of the source maps limits the spatial resolution (scale) of the database to 
1:24,000 or smaller.  The content and character of the database are described 
briefly herein.  A more detailed description is available with the database.
Two methods of obtaining the database are described below.

Database Contents

The Quaternary geologic digital database itself consists of eight ARC coverages:
	cal_utm	Quaternary geology of Calaveras Reservoir 
		quadrangle 
	cup_utm	Cupertino quadrangle
	mil_utm	Milpitas quadrangle  (Helley and Wesling, 1989)
	mtv_utm	Mountain View quadrangle
	pal_utm	Palo Alto quadrangle
	sje_utm	San Jose East quadrangle (Helley and Wesling, 
		1990)
	sjw_utm	San Jose West quadrangle  (Wesling and Helley, 
		1989)
	sth_utm	Santa Teresa Hills quadrangle

The database directory also includes the following directories, ARC coverages, 
and files:
	info/		INFO directory containing files supporting the 	
			databases

	explsc_utm
and	explsc_ano	Together, these ARC coverages produce a plottable 
			or displayable map explanation and key.
	corr_utm	
and	corr_ano	Together, these ARC coverages contain a correlation 
			table for the units in these maps.

	scc_dr		Drainage base map.
	scc_cu		Cultural base map.
	scc_topo	Topographic contours base map.

	scgeo.txt	A text file containing detailed unit descriptions and 
			geological information.
	scdb.txt	A detailed description of the contents and character
			of this database.
	scmap.ps	A Postscript  plottable file containing an image of 
			the Quaternary geologic maps of all eight quadrangles, 
			base maps, and map explanation at a scale of 1:50,000.
	
	The database was compiled in ARC/INFO, a commercial Geographic 
Information System (Environmental Systems Research Institute, Redlands, 
California), and is stored in ARC coverage format (ARC/INFO version 6) in a UNIX
tar file.  A UNIX computer system is therefore required to extract the database 
from the tar file, and ARC/INFO is required for its use or conversion to other 
format.  The digital compilation was done using version 6.1.1 of ARC/INFO with 
version 2.0 of the menu interface ALACARTE (Fitzgibbon and Wentworth, 1991, 
Fitzgibbon, 1991, Wentworth and Fitzgibbon, 1991).

Obtaining the Digital Data

To obtain the tar file from the Internet, go to:
	http//pubs.usgs.gov/of/1994/of94-231/

Extracting the Database from the Tar file

If you obtained the database on tape:
	put the tape in your tape drive
	cd local_directory		-go to a directory to receive the
						tar file
	tar xvfb /dev/rstn 20		-/dev/rstn is the tape device with 
						n an integer, this puts the tar 
						file in local_directory
	uncompress scc_q1.tar.Z		-makes a 20 MB uncompressed 
						tar file scc_q1.tar
	cd local_directory2		-go to the directory that will hold 
						the workspace sccq (if different
 						from local_directory)
	tar xvfb {path to tar 
	file}/scc_q1.tar 20		-extract the sccq workspace from 
						the tar file.


This process will create a workspace "/sccq" (a directory containing an INFO 
directory) that contains the databases and supporting files as described above.