ssfb_m1.ReadMe

The 3.7 MB compressed tar file ssfb_m1.tar.Z contains the data for USGS 
Open-File Report  93-693

GENERAL DISTRIBUTION OF GEOLOGIC MATERIALS IN THE SOUTHERN SAN FRANCISCO BAY
REGION, CALIFORNIA:  A DIGITAL MAP DATABASE

digitally compiled by 

Carl M. Wentworth

1993

To extract the database from the tar file (after copying to your Unix system):

  uncompress ssfb_m1.tar.Z  - this makes a 5.42 MB uncompressed tar file
                              ssfb_m1.tar
  cd local_directory2	    - go to the directory that will hold the ssfbay   
                              workspace (if different from local_directory)
  tar  xvfb [path to tar file]/ssfb_m1.tar 20 - extract the ssfbay workspace  
                              from the tar file

This process will create a workspace (directory containing an INFO directory)
that contains the ssfb_m1 database as follows:

	/ssfbay		- workspace
	  info/		- an ARC/INFO database directory containing the FM2FORM
			  table (INFO file) and other files  that support the 
			  ssfb_m1 coverage.
	  m1.text	- text description of the database.
	  ssfb_m1	- an ARC coverage directory containing the digital 
			  map (ssfb_m1)

Brief Description:   

The ssfb_m1 digital map database, which is compiled from 1970's vintage 
sources, represents the general distribution and identity of geologic 
materials in the southern San Francisco Bay region, California, west of the 
Calaveras fault.  It is not a geologic map, because it does not address the
geologic structure or the stratigraphic organization of the map units in a
systematic way.  Instead, it is directed at the distribution and character of
the geologic materials following the pattern of its progenitors, Wentworth and
others (1985) and Ellen and Wentworth (in press).  Consultation of these
reports and the other compilation sources will aid in using the database.

The database delineates map units that are identified by general age and
lithology and by the map labels used in the compilation sources. 
Stratigraphic names are included for those units named in the sources as a
further means of characterization. The scales of the source maps limit the
spatial resolution (scale) of the database to 1:125,000 or smaller.  It can be
used alone or, where more specific information about the units is needed, in
concert with the unit descriptions in the compilation sources or other means
of unit characterization.  It is useful for regional considerations that
involve geologic materials, but does not replace the more detailed and
up-to-date information required for evaluation of local areas.

The database was compiled in ARC/INFO, a commercial Geographic Information
System (Environmental Systems Research Institute [ESRI], Redlands,
California), and is stored in ARC coverage format (ARC/INFO version 6) in a
UNIX tar file.  A UNIX computer system is thus required to extract the
database from the tar file and ARC/INFO is required for its use, or at least
for conversion of the database to an alternative digital format.