U.S. DEPARTMENT OF THE INTERIOR
                              U.S. GEOLOGICAL SURVEY




                             PRELIMINARY GEOLOGIC MAP 

                                     OF THE
  
                 SAN JOSE 30 X 60 MINUTE QUADRANGLE. CALIFORNIA


                               A DIGITAL DATABASE



                                    By



                   Carl M. Wentworth, M. Clark Blake, Jr., 
                 Robert J. McLaughlin, and Russell W. Graymer





                          Open-File Report 98-795




                                      1999









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 geologic map of the San Jose 30 X
60-minute quadrangle, California: a digital database', has been approved for
release and publication by the Director of the USGS. Although this database
has been reviewed and is substantially complete, the USGS reserves the right
to revise the data pursuant to further analysis and review. This database is
released on condition that neither the USGS nor the U.S. Government may be
held liable for any damages resulting from its use.




                                  INTRODUCTION


This report presents the preliminary geologic map of the San Jose 30 x
60-minute quadrangle at a scale of 1:100,000, and consists of a spatial
database of nine layers, two colored map sheets (geologic map and correlation
diagram), and a descriptive text, as well as this pamphlet. The spatial
database, map sheets, and descriptive text are all digital, and this pamphlet
describes the digital files and how to obtain them by downloading across the
Internet or ordering copies on magnetic tape.

The San Jose 30 x 60-minute quadrangle straddles the California Coast Ranges
southeast of San Francisco, and extends from west of the San Andreas fault
near Santa Cruz on the southwest (long. -122*, lat. 37*) to the San Joaquin
River in the Central Valley on the northeast (long. -121*, lat. 37.5*). The
map is a new geologic compilation that is based on extensive previous work by
many authors and a great deal of new mapping, largely at 1:24,000, much of
which is previously unpublished. 

This report adds to a series of reports about the San Jose 30 x 60-minute
quadrangle that includes summaries of macro- and microfossil localities (Elder
and Miller, 1990; Elder and Miller, 1993; Sliter and others, 1993), a
description of new radiometric ages and tephra correlations (Nakata and
others, 1993), a map of isostatic residual gravity (Chuchel and Jachens,
1990), an aeromagnetic map (Roberts and Jachens, 1993), and a delineation of
landform types (Pike and others, 1992).

This open-file pamphlet and the geologic description are provided in ASCII,
PostScript, and PDF format for viewing and plotting. (The ASCII version of the
geologic description contains no figures.) 

The two map sheets (geologic map and correlation diagram) are presented as
digital plot files in PostScript and PDF format (image sizes of 52 x 27 and 29
x 17 inches). The PostScript map images (96 and 1.5 MB) can be used for
viewing or plotting in systems with sufficient capacity, and the considerably
smaller PDF files (18 and 0.5 MB) can be viewed or plotted in full or in part
from Adobe ACROBAT running on Mac, PC, or UNIX platforms. The appearance of
the geologic map in plots (area and line colors and line weights) will depend
on file type and the particular plotter that is used. 

The nine layers in the spatial database are provided both as uncompressed
ARC/INFO export files in Version 7 format and as ArcView Shape files. These
include three geologic data layers (geology, tectonic blocks, and annotation
[largely landslide arrows]), a 7.5-minute quadrangle index, and five
topographic base layers (drainage, index and intermediate contours, culture,
and township/range lines). The full versatility of the spatial database is
obtained by importing the ARC export files into ARC/INFO or an equivalent GIS
package. Other GIS packages, including MapInfo and ARCVIEW, may use either the
ARC export or Shape files, although the Shape files do not retain the
definition tables or text annotation. The information in the definition tables
is repeated in this pamphlet (except geologic units) and in the geologic
description (geologic units).

The geologic database was compiled in vector form over the past decade with
versions 4 through 7.2.1 of ARC/INFO, a commercial Geographic Information
System (Environmental Systems Research Institute [ESRI], Redlands,
California), on UNIX computers using the menu interface ALACARTE (versions 1
through 3.5: Fitzgibbon and Wentworth, 1991; Fitzgibbon, 1991; Wentworth and
Fitzgibbon, 1991). The topographic base layers are vectorized raster scans
prepared on SCITEX equipment by D. S. Aitken from film-positive separations of
the 1:100,000 printing negatives of the U.S. Geological Survey 1:100,000 San
Jose, California,  topographic map (1978). The geologic map was assembled as a
graphics file in ARC/INFO from the spatial database, using standard ALACARTE
procedures (Qs_plot), the ALACARTE lineset and lookup table, and a custom
color set (shadeset).


                                 Database Contents

The report consists of digital files representing the eight parts of the
database, most of which are presented in more than one format. The names of
the files are unique designators based on the report identifier, of98-795,
followed by part numbers and an extension indicating file type. Some of the
files have been bundled in tape archive files (tar files; .tar extension) and
the larger ones have been compressed with gzip, yielding a final .gz extension
(see Presentation, below). The files and their identities are as follows:

  1. Revision List: A list of the parts of the report (including bundled 
     packages of parts) and at what version number of the report each was last 
     revised (if at all), followed by a chronologic list that describes any 
     revisions (see REVISIONS, below).

     a. of98-795_1a.txt     ASCII file                                     

  2. Open-File Pamphlet: The text of the open-file pamphlet (this text), which
     describes the database and how to obtain it.

     a. of98-795_2a.txt   ASCII file, 0.04 MB.                                

     b. of98-795_2b.ps   PostScript file, 0.2 MB

     c. of98-795_2c.pdf   PDF file, 0.04 MB  

  3. Geologic Description: A 52-page text that describes the geology of the map
     area and the 136 map units.                      

     a. of98-795_3a.txt   ASCII file, 0.2 MB.                                

     b. of98-795_3b.ps   PostScript file, 1.2 MB

     c. of98-795_3c.pdf   PDF file, 0.3 MB  



  4. Geologic Database: The data files representing the lines and polygons of
     the geology layer, the lines and text of the annotation layer, the points 
     of the tectonic blocks layer, and the lines, polygons, and text of the 
     quadrangle index (ARC export and ARCVIEW Shape formats). Note that the 
     definition tables within the ARC coverages and text in the annotation layer
     are not retained in the Shape files.

     a. of98-795_4a.e00.gz -- Geology: compressed ARC export coverage containing
                 both lines and polygons (6 MB, uncompresses to 32 MB). 
                 Import.aml will name this coverage sj-geol.

     b. of98-795_4b.e00 --  Tectonic blocks: ARC export coverage containing 
                 points (0.2 MB). Import.aml will name this coverage sj-blks.   

     c. of98-795_4c.e00 -- Annotation: ARC export coverage containing lines
                 (leaders and landslide arrows) and several labels (1.3 MB). 
                 Import.aml will name this coverage sj-anno.

     d. of97-744_4d.tar.gz -- Geology: ARCVIEW line and polygon Shape files 
                 bundled as one compressed tar file (20 MB, uncompresses to 
                 30 MB). When opened, the tar file yields:

                 - line files: sjglns.dbf, sjglns.shp, and sjglns.shx
                 - polygon files: sjgpys.dbf, sjgpys.shp, and sjgpys.shx

     e. of97-744_4e.tar -- Tectonic blocks: ARCVIEW point Shape files bundled 
                 as one tar file (0.08 MB). When opened, the tar file yields:

                 - point files: sjbpts.dbf, sjbpts.shp, and sjbpts.shx

     f. of97-744_4f.tar -- Annotation: ARCVIEW line Shape files bundled as  
                 one tar file (0.7 MB). When opened, the tar file yields:

                 - line files: sjalns.dbf, sjalns.shp, and sjalns.shx

  5. Quadrangle Index Database: The data files representing the lines and
     polygons of the quadrangle index (ARC export and ARCVIEW Shape format). 
     The ARC version also includes quadrangle names as annotation.

     a. of98-795_5a.e00 -- ARC export coverage containing lines, polygons, and
                 annotation (0.2 MB). Import.aml will name this coverage 
                 sj-qdgrid. 

     b. of98-795_5b.tar -- ARCVIEW line and polygon shape files bundled as one 
                 tar file (0.09 MB). When opened, the tar file yields:

                 - line files: sjqlns.dbf, sjqlns.shp, and sjqlns.shx
                 - polygon files: sjqpys.dbf, sjqpys.shp, and sjqpys.shx

  6. Topographic Base Database: The data files representing the lines of the
     five topographic base layers drainage, index contours, intermediate 
     contours, culture, and land lines (township/range)  (ARC export and ARCVIEW
     Shape format).

     a. of98-795_6a.e00 -- Drainage: ARC export coverage containing lines (14.2
                 MB). Import.aml will name this coverage sj-drain. 

     b. of98-795_6b.e00 -- Index contours: ARC export coverage containing lines 
                 (3.8 MB). Import.aml will name this coverage sj-index. 

     c. of98-795_6c.e00 -- Intermediate contours: ARC export coverage containing
                 lines (14.9 MB). Import.aml will name this coverage sj-inter. 

     d. of98-795_6d.e00 -- Culture: ARC export coverage containing lines 
                 (19 MB). Import.aml will name this coverage sj-cult. 

     e. of98-795_6e.e00 -- Land: ARC export coverage containing lines (1 MB).
                 Import.aml will name this coverage sj-land. 

     f. of98-795_6f.tar -- Drainage: ARCVIEW line Shape files bundled as one 
                 tar file (8.8 MB). When opened, the tar file yields:

                 - line files: sjdlns.dbf, sjdlns.shp, and sjdlns.shx

     g. of98-795_6g.tar -- Index contours: ARCVIEW line Shape files bundled as 
                 one tar file (2.3 MB). When opened, the tar file yields:

                 - line files: sjilns.dbf, sjilns.shp, and sjilns.shx

     h. of98-795_6h.tar -- Intermediate contours: ARCVIEW line Shape files 
                 bundled as one tar file (8.8 MB). When opened, the tar file 
                 yields:

                 - line files: sjnlns.dbf, sjnlns.shp, and sjnlns.shx

     i. of98-795_6i.tar -- Culture: ARCVIEW line Shape files bundled as one tar
                 file (14.9 MB). When opened, the tar file yields:

                 - line files: sjclns.dbf, sjclns.shp, and sjclns.shx

     j. of98-795_6j.tar -- Land: ARCVIEW line Shape files bundled as one tar 
                 file (0.8 MB). When opened, the tar file yields:

                 - line files: sjllns.dbf, sjllns.shp, and sjllns.shx

  7. Plot File of Geologic Map: image size 52 x 27 inches. The PostScript 
                 version is rotated so that the long axis plots in the 
                 Y direction.

     a. of98-795_7a.ps  PostScript file, 96 MB

     b. of98-795_7b.pdf  PDF file, 18 MB

  8. Plot File of Correlation Diagram: image size 29 x 17 inches

     a. of98-795_8a.ps  PostScript file, 1.5 MB

     b. of98-795_8b.pdf  PDF file, 0.5 MB


                                   Presentation

The database files are provided individually (including Shape files packaged 
in tar files by equivalent ARC coverages) and some of these are also packaged 
together in larger tape archive files (.tar). Most of the larger files have 
been compressed with gzip (.gz).

Separate Text Files: The revision list (of98-795_1a.txt) and the three formats
of the open-file text (of98-795_2) and the geologic description (of98-795_3)
are provided separately, together with an abbreviated version of the ASCII
text version as a README. These text files in all three formats are also
bundled in the database package.

Separate Database Files: The geologic database (of98-795_4) and the
quadrangle-index database (of98-795_5) are provided separately in both ARC
export (.e00) and ARCVIEW shape (.tar) formats, as well as being bundled in
the database package files (see below).

Separate Plot Files: The plot files for the geologic map and correlation
diagram are provided separately in both PostScript and PDF format, as well as
being bundled together in the plotfile package (see below).

Topographic Base Package: The five vector base layers (drainage, index and
intermediate contours, culture, and land lines) are packaged together in both
ARC export (a) and ARCVIEW shape (b) formats as gzip-compressed tar files:

			of98-795_9a.tar.gz   10 MB, uncompresses to 53 MB

			of98-795_9b.tar.gz   9 MB, uncompresses to 36 MB

Database Package: The geologic map layers (geology, blocks, and annotation -
of98-795_4) and the quadrangle index (of98-795_5) are packaged together in a
single gzip-compressed tar file in both ARC (a) and ARCVIEW shape (b) format.

			of98-795_10a.tar.gz   7 MB, uncompresses to 36 MB

			of98-795_10b.tar.gz   21 MB, uncompresses to 33 MB

Plotfile Package: Plotfiles of the geologic map and the correlation diagram
are packaged together in a single gzip-compressed tar file in both PostScript
(a) and PDF (b) format.

			of98-795_11a.tar.gz   19 MB, uncompresses to 99 MB

			of98-795_11b.tar.gz   19 MB


                          OBTAINING THE DIGITAL FILES

The database and image files can be downloaded from the Western Region
Geologic Information Web Server or by anonymous ftp over the Internet, or can
be obtained by submitting a tape on which requested files will be copied and
returned.

1. Send a tape with a request for the desired files to: 

 	San Jose 100K Geologic Map
	c/o Database Coordinator
	U.S. Geological Survey
	345 Middlefield Road, MS 975
	Menlo Park, CA 94025

The file(s) will be returned on the tape.  The acceptable tape types are:

	4.3 or 5.0 GB, 8 mm Exabyte tape

In the request, be sure to include the Open-File Report number and the
specific names of the file(s) that you want, using the names listed in the
Report Contents section above.  An Open-File Report number alone is not
sufficient, because there are several parts to the report and they are
available in different file types. If you are obtaining a plot file on tape to
give to a vendor to plot, make sure that your vendor is capable of reading the
tape type and file type (PostScript or PDF). 

2.  Anonymous ftp over the Internet

The files for this report are stored on the Western Region publication server
of  the U.S. Geological Survey.  The Internet address of this server is:

	wrgis.wr.usgs.gov

Connect to this address directly using ftp or through a browser, log in with
the user name `anonymous', and enter your e-mail address as the password. 
This will give you access to all the publications available from the server.
The files for this report are stored in the subdirectory:

	pub/open-file/of98-795

3.  From the Western Region Geologic Information Web Server

The U.S. Geological Survey supports a set of graphical pages on the World Wide
Web from which digital publications such as this one can be obtained.  The Web
server for digital publications from the Western Region is:

	http://geology.wr.usgs.gov


                               PROCESSING THE FILES

The database files require initial processing before they are useable, both to
open bundled and/or compressed files and to import ARC export files.


                            Opening Tar and Gzip Files

Some of the files are assembled as tape archive files (tar files), and the
larger files containing the databases and images have been compressed with
gzip. Thus gzip is required to uncompress the files, and a tar utility is
required to open the tar files. Once extracted from the compressed tar files,
the ARC export files can be imported into ARC/INFO using the utility
import.aml that is included in the database package, or directly using  the
ARC import command.

The necessary utilities for uncompressing and extracting from tar format are
available on-line: 

gzip - This utility is available free of charge over the Internet from the
       gzip Home Page:

             http://w3.teaser.fr/*jlgailly/gzip

       or via links from the USGS Public Domain Software page: 

             http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/public.html

tar - This utility is included in most UNIX systems. Tar utilities for PC and
       Macintosh can be obtained free of charge via the Internet from Internet
       Literacy's Common Internet File Formats Web Page:  

             http://www.matisse.net/files/formats.html

Winzip - This commercial package runs on PCs and can deal with both gzip and
       tar files. An evaluation copy of WinZip for Windows 3.1, 95 and NT can 
       be downloaded from:

             http://www.winzip.com/winzip/:  


                          Importing the ARC Export Files

The ARC export files (__.e00) can be converted to ARC/INFO vector maps
(coverages) and associated INFO files by running the import.aml that is
included in the database package. This will import the export files, assign
standard names (see below), build polygon topology where appropriate (if
desired), and delete the export files once used (if desired). The 'build' and
'delete' options are enabled by answering YES to questions posed when the aml
starts running. Rerunning the aml permits enabling those options previously
rejected, but will not interfere with the results of earlier runs. The import
routine checks for the presence of needed export files, for previously
imported files, and for the need to build if that option is enabled. Run
import.aml from the ARC prompt in the directory containing the export files:

   ARC: &run import.aml	- run import.aml, answer YES/NO to the questions posed
                          in the dialog area to choose options to import the 
                          export files, keep or delete the export files, and 
                          build the imported polygon coverages. 

Note that the arc coverages will be given standard names:

      of98-795_4a.e00  	(Geology Layer) 	is named     sj-geol

      of98-795_4b.e00  	(Blocks Layer)                       sj-blks

      of98-795_4c.e00  	(Annotation Layer)    		     sj-anno

     of98-795_5a.e00  	(Quadrangle Index)      	     sj-qdgrid

     of98-795_6a.e00    (Drainage Layer)     	             sj-drain

     of98-795_6b.e00    (Index Contour Layer)  	             sj-index

     of98-795_6c.e00    (Intermediate Contour Layer)         sj-inter

     of98-795_6d.e00    (Culture Layer)             	     sj-cult

     of98-795_6e.e00    (Land Line Layer)             	     sj-land


                                    REVISIONS

Changes to any part of this report (parts are the numbered items described
above in 'Report Contents' and listed in the revision list of98-795_1a.txt)
may be made in the future if needed. This could involve, for example, fixing
files that don't work, correcting geologic details, adding new file formats,
or adding other components to the report.

The report begins at version 1.0. Any revisions will be specified in the
revision list and will result in the recording of a new version number for the
report. Small changes will be indicated by decimal increments and larger
changes by integer increments in the version number. Revisions will be
announced and maintained on the Web page for this report on the Western Region
Geologic Information Web Server. Consult the revision list there to determine
if a revision is significant for your purposes.


                                 MAP COMPILATION

The geologic database was compiled digitally in vector form as individual
7.5-minute quadrangles from source materials ranging in scale from 1:12,000 to
1:62,500. Much of the material was initially fitted to 1:24,000 topography in
polyconic or California State Plane (zone 4) projection. These were converted
to UTM (see below), and the larger resulting departures from the 1:100,000
base then refitted to that base. Some of the most detailed areas, particularly
in the Santa Cruz Mountains and the Del Puerto Ophiolite, were simplified for
smaller scale presentation. The geology layers for the 32 individual
quadrangles were assembled into a single layer for the 1:100,000 map area and
interior quadrangle boundaries were removed. The locations and identities of
tectonic blocks in the Diablo Range were similarly compiled, both from mapped
points and from areas too small to show at scale (diameter less than 100 m) or
representing aggregates of blocks. The resulting spatial database and standard
symbol sets in ALACARTE were then used to prepare the colored geologic map
image presented here. Some of the details in the spatial database, although
retained in the 1:100,00 image, are too small for legible portrayal at that
scale.


                               SPATIAL RESOLUTION

Uses of this digital database should not violate the spatial resolution of the
data.  Although the digital form of the data removes the physical constraint
imposed by the scale of a paper map, the detail and accuracy inherent in map
scale are also present in the digital data. The fact that this database was
compiled from maps having scales ranging from 1:12,000 to 1:62,500 and then
was selectively simplified for 1:100,000 presentation means that information
of resolution higher than 1:100,000 cannot be ensured in any particular part
of the database. Use of the database at larger scales may not yield greater
real detail, although it may reveal fine-scale irregularities below the
intended resolution of the database.  Similarly, where this database is used
in combination with other data of higher resolution, the resolution of the
combined output will be limited by the lower resolution of this data.    


                        DESCRIPTION OF THE SPATIAL DATABASE

The San Jose spatial database consists of three geologic layers (geology,
tectonic blocks, and annotation) and five topographic base layers (drainage,
index and intermediate contours, culture, and land lines), all in vector form.
The geologic layers follow the ALACARTE data model, in which contacts, faults,
and geologic-unit polygons are stored in a geology layer (including dangling
faults), specialized points (here, tectonic blocks) are stored in a separate
layer, and cartographic elements are stored in an annotation layer. (No
structure layer is included in this database.) Furthermore, following the data
model described by Gautier (1999) for single geologic maps, topical attributes
are limited to a single primary attribute for each feature type in each layer
and the different values of those database fields (items) are defined in
definition tables included in each layer. The base layers have no topical
attributes, although all include a line database (AAT).

The ARC layers (coverages) are stored in UTM projection (table 1), whereas the
Shape files are in decimal degrees of longitude and latitude, prepared by
projecting and converting the primary UTM coverages. 


                            Table 1.  Map Projection

		Projection	utm	(Universal Transverse Mercator)
		Units 		meters
		Zone 		10
		Datum		NAD27
		Spheroid	CLARKE1866


The contents of the several database layers are described in terms of the
lines, polygons, points, and text that compose them. Descriptions of the
database fields (items) use the terms of table 2.


                       Table 2.  Field Definition Terms

	ITEM NAME 	name of the database field  (item) 	
	WIDTH		maximum number of digits or characters stored
	OUTPUT		output width
	TYPE 		B- binary integer, F- binary floating point number, N- 
			  ASCII floating point number, I- ASCII integer, 
			  C- ASCII character string
	N.DEC		number of decimal places maintained for floating 
			point numbers


                                 Geology Layer 

The complex geology layer contains attributed lines and polygons and requires
polygon topology for effective use (ARC build poly). The line database
(SJ-GEOL.AAT, table 3) contains the topical attribute field LTYPE, the 14
values of which are described in table 4 and in digital form as part of the
sj-geol coverage in the INFO definition table SJ-GEOL.LN.


         Table 3.  Contents of the Geology Arc Attribute Table (SJ-GEOL.AAT)

    ITEM NAME  WIDTH  OUTPUT   TYPE   N.DEC  

    FNODE#    	 4      5       B       -     starting node of arc (from node)
    TNODE#       4     	5     	B      	-     ending node of arc (to node)
    LPOLY#       4     	5     	B      	-     polygon to the left of the arc
    RPOLY#       4     	5     	B      	-     polygon to the right of the arc
    LENGTH       4     12     	F      	3     length of arc in meters
    SJ-GEOL#   	 4     	5     	B      	-     unique internal control number
    SJ-GEOL-ID 	 4     	5     	B      	-     unique identification number
    LTYPE       35     35     	C      	-     line type


             Table 4.  Line Types Recorded in the Geology LTYPE Field

    The geologic line types (exclusive of the various kinds of boundaries) 
    are ALACARTE line types that correlate with geologic line symbols in the 
    ALACARTE line set GEOLOGY.LIN according to the ALACARTE lines lookup 
    table GEOLINE.LUT.

	  LTYPE 				  LDEF

     contact, certain	  	  unfaulted depositional or intrusive boundary 
				  between map units, confident identification 
				  and location

     contact, approx. located     unfaulted depositional or intrusive boundary 
				  between map units, relatively confident 
				  identification, location approximate

     contact, inferred		  unfaulted depositional or intrusive boundary 
				  between map units, identification inferred, 
				  location approximate

     contact, inferred, queried	  unfaulted depositional or intrusive boundary
				  between map units, identification inferred, 
				  location uncertain

     contact, concealed		  unfaulted depositional or intrusive boundary 
				  between map units, concealed beneath overlying
				  map unit, identification and location 
				  dependant on adjacent control

     fault, certain		  fault showing mappable disruption of map units
				  or separating coherent Franciscan rock from 
				  melange, confident identification and location

     fault, approx. located	  fault showing mappable disruption of map units
				  or separating coherent Franciscan rock from 
				  melange, relatively confident identification, 
				  location approximate

     fault, inferred		  fault showing mappable disruption of map units
				  or separating coherent Franciscan rock from 
				  melange, identification inferred, location 
				  uncertain

     fault, inferred, queried	  fault showing mappable disruption of map units
				  or separating coherent Franciscan rock from 
				  melange, identification inferred, location 
				  uncertain

     fault, concealed		  fault showing mappable disruption of map units
				  or separating coherent Franciscan rock from 
				  melange, concealed beneath overlying map unit,
				  identification and location dependant on 
				  adjacent control

     fault, concealed, queried	  fault showing mappable disruption of map units
				  or separating coherent Franciscan rock from 
				  melange, concealed beneath overlying map unit,
				  identification and/or location uncertain

     map boundary		  boundary of San Jose 30 X 60-minute quadrangle

     scratch boundary		  boundary without geologic attribute, here used
				  to close otherwise incomplete unit boundaries 
				  (largely narrow stream channels - Qa),
 				  assign no line symbol in plotting

     water boundary		  boundary of open water from 1:100,000 base


The geology polygon database (SJ-GEOL.PAT, table 5) contains the topical
attribute field PTYPE, values of which are map-label representations of the
geologic map units (such as Qt). The 136 map units (and 40 queried
equivalents) are listed and described in the separate geologic description
(part of98-795_2) and are listed and named in digital form as part of the
sj-geol coverage in the INFO definition table SJ-GEOL.UN.


    Table 5.  Contents of the Geology Polygon Attribute Table (SJ-GEOL.PAT)

    ITEM NAME  WIDTH  OUTPUT   TYPE   N.DEC  

    AREA    	 4      12     	F      	3      area of polygon in square meters
    PERIMETER    4      12     	F      	3      length of perimeter in meters
    SJ-GEOL#     4     	5     	B      	-      unique internal control number
    SJ-GEOL-ID   4     	5     	B      	-      unique identification number
    PTYPE       35      35     	C      	-      geologic unit label


                               Tectonic Blocks Layer 

Tectonic blocks of relatively high metamorphic grade in Franciscan melange
that are too small to show at map scale (diameter less than 100 m) are
represented as points in the blocks layer sj-blks (and shown as black diamonds
on the geologic map), except in the Santa Cruz Mountains, where they are not
distinguished. The blocks point database (SJ-BLKS.PAT, table 6) contains the
topical attribute field BKTYPE, containing letter codes representing rock
type. The 7 code values are defined in table 7 and in digital form as part of
the sj-blks coverage in the INFO definition table SJ-BLKS.PT.


Table 6.  Contents of the Blocks Point Attribute Table (SJ-BLKS.PAT)

    ITEM NAME  WIDTH  OUTPUT   TYPE   N.DEC  

    AREA    	 4      12     	F      	3      (unused for points)
    PERIMETER    4      12     	F      	3      (unused for points)
    SJ-BLKS#     4     	 5     	B      	-      unique internal control number
    SJ-BLKS-ID   4     	 5     	B      	-      unique identification number
    BKTYPE       2    	 2      C      	-      code for type of block


                      Table 7.  Types of Tectonic Blocks

	         BKTYPE 		BDEF 



     		   a	   amphibolite, garnet amphibolite

    		   b	   blueschist

  		   e	   eclogite

 		   h	   highgrade, undifferentiated

  		   m	   mica schist

  		   t	   greenschist

  		   y	   grayblack schist, Ward Creek terrane?


                                 Annotation Layer 

The annotation layer sj-anno contains cartographic elements that are designed
for plotting with the geology layer. Text is limited to three unit labels (all
other labels on the geologic map were created with the ArcPlot polygontext
command) and the designation "SHEAR ZONE", which plots over the map unit PTYPE
= sz (text size appropriate for 1:100,000-scale plots). Lines are leaders for
the three labels and more than 1500 landslide arrows. These lines are
distinguished by values of the LTYPE attribute field in the line database
(SJ-ANNO.AAT, table 7), which are defined in table 8 and in digital form as
part of the sj-anno coverage in the INFO table SJ-ANNO.LN. For the best effect
in plotting, exclude the Qls PTYPE labels when including the landslide arrows.


   Table 7.  Contents of the Annotation Arc Attribute Table (SJ-ANNO.AAT)

   ITEM NAME             WIDTH  OUTPUT     TYPE   N.DEC  

    FNODE#    	 4       5       B       -     starting node of arc (from node)
    TNODE#       4     	5     	B      	-     ending node of arc (to node)
    LPOLY#       4     	5     	B      	-     polygon to the left of the arc
    RPOLY#       4     	5     	B      	-     polygon to the right of the arc
    LENGTH       4      12     	F      	3     length of arc in meters
    SJ-ANNO#   	 4     	5     	B      	-     unique internal control number
    SJ-ANNO-ID   4     	5     	B      	-     unique identification number
    LTYPE       35      35     	C      	-     line type


          Table 8.  Line Types Recorded in the Annotation LTYPE Field

	  LTYPE 			LDEF

	landslide arrow		landslide arrow, points down slope

    	leader			leader, connects unit label annotation 
				with unit polygon


                                Quadrangle Index 

The boundaries and names of the thirty-two 7.5-minute quadrangles in the San
Jose 30 X 60-minute quadrangle are described in the quadrangle index
sj-qdgrid. This layer distinguishes the outer from the internal quadrangle
boundaries and names the 7.5-minute quadrangles both by polygon attribute and
with text annotation.  Quadrangle boundaries are distinguished by values of
the LTYPE attribute field in the line database (SJ-QDGRID.AAT, table 9), which
are defined in table 10 and in digital form as part of the sj-qdgrid coverage
in the INFO table SJ-QDGRID.LN.


 Table 9.  Contents of the Quadrangle Index Arc Attribute Table (SJ-QDGRID.AAT)



   ITEM NAME             WIDTH  OUTPUT     TYPE   N.DEC  

    FNODE#    	  4      5      B       -     starting node of arc (from node)
    TNODE#        4      5     	B      	-     ending node of arc (to node)
    LPOLY#        4      5     	B      	-     polygon to the left of the arc
    RPOLY#        4      5     	B      	-     polygon to the right of the arc
    LENGTH        4     12     	F      	3     length of arc in meters
    SJ-QDGRID#    4      5     	B      	-     unique internal control number
    SJ-QDGRID-ID  4      5     	B      	-     unique identification number
    LTYPE        35     35     	C      	-     line type


     Table 10.  Line Types Recorded in the Quadrangle Index LTYPE Field

		
            LTYPE 		      LDEF

	quadboundarys	    boundary of 7.5-minute quadrangle, exclusive of 
			    outer boundary of 1:100,000 quadrangle

	sheetboundary	    outer boundary of 1:100,000 quadrangle


Quadrangle names are specified in the NAME attribute field of the the polygon
database (table 10), as well as by text annotation in both diagonal
(quad-centered, level 2) and horizontal (upper left of each quadrangle, level
3) orientation. 


    Table 10.  Contents of the Quadrangle Index Polygon Attribute Table
	       (SJ-QDGRID.PAT)

    ITEM NAME  WIDTH  OUTPUT   TYPE   N.DEC  

    AREA    	  4      12     F      	3      area of polygon in square meters
    PERIMETER     4      12     F      	3      length of perimeter in meters
    SJ-QDGRID#    4       5     B      	-      unique internal control number
    SJ-QDGRID-ID  4       5     B      	-      unique identification number
    NAME         35    	 35     C      	-	name of 7.5-minute quadrangle 


                                 Topographic Base 

The topographic base layers are unattributed vector representations of
printing negative separations for the U.S. Geological Survey 1:100,000 San
Jose, California, topographic map (1978) that have been aggregated or
distinguished to produce the five layers of table 11. Distinction between the
index and intermediate contours was accomplished by recognizing the difference
in line widths during vectorization. No hand editing has been applied to the
results of the automatic vectorization and, although the resulting vector
representation of the separations is generally quite legible, artifacts and
distortions did result, particularly from letters and numbers. 


                      Table 11.  Topographic Base Layers

		   Topic		Layer Name

		Drainage		 sj-drain

		Index Contours		 sj-index

		Intermediate Contours	 sj-inter

		Culture		         sj-cult

		Township-Range Lines	 sj-land


                                REFERENCES CITED

Chuchel, B.A., and Jachens, R. C., 1990, Preliminary isostatic residual
  gravity map of the San Jose 1:100,000 scale quadrangle, California: U.S.
  Geological Survey Open-File Report 90-55, map scale 1:100,000.

Elder, W.P., and Miller, J.W., 1990, Checklists of Jurassic and Cretaceous
  macrofauna from U.S. Geological Survey collections within the San Jose
  1:100,000 map sheet, California: U.S. Geological Survey Open-File Report
  90-534 map scale 1:100,000.

Elder, W.P., and Miller, J.W., 1993, Map and checklists of Jurassic and
  Cretaceous macrofossil localities within the San Jose 1:100,000 map sheet,
  California, and discussion of paleontological results: U.S. Geological Survey
  Open-File Report 93-503 map scale 1:100,000.

Fitzgibbon, T.T., 1991, ALACARTE installation and system manual (version 1.0):
  U.S. Geological Survey, Open-File Report 91-587B.

Fitzgibbon, T.T., and Wentworth, C.M., 1991, ALACARTE user interface - AML
  code and demonstration maps (version 1.0): U.S. Geological Survey, Open-File
  Report 91-587A.

Gautier, D.L., 1999, Data model for single geologic maps: an application of
  the national geologic map data model, in, Soller, D.R., ed., Digital mapping
  techniques '99 -- workshop proceedings: U.S. Geological Survey Open -File
  Report 99-386.

Nakata, J.K., Sorg, D.H., Russell, P.C., Meyer, C.E., Wooden, J., Lanphere,
  M.A., McLaughlin, R.J, Sarna-Wojcicki, A.M., Saburomaru, J.Y., Pringle, M.S.,
  and Drinkwater, J., 1993, New Radiometric ages and tephra correlations from
  the San Jose and the northeastern part of the Monterey 1:100,000 map
  quadrangles, California: Isochron/West, v. 60, p. 19-32.


Pike, R.J., Acevedo, William, and Showalter, P.K., 1992, Mapping topographic
  form by digital image-processing in the San Jose 1:100,000 sheet, California:
  U.S. Geological Survey Open-File Report 92-420, 56 p.

Roberts, C.W., and Jachens, R.C., 1993, Aeromagnetic map of the San Jose
  1:100,000-scale quadrangle, California: U.S. Geological Survey, Open-File
  Report 93-277.

Sliter, W.V., McDougall, Kristin, Murchey, B.L., and Kohnen, E.V., 1993,
  Mesozoic and Cenozoic microfossils from geologic units within the San Jose
  1:100,000 quadrangle, California: U.S. Geological Survey Open-File Report
  93-344, map scale 1:100,000.

Wentworth, C.M., and Fitzgibbon, T.T., 1991, ALACARTE user manual (version
  1.0): U.S. Geological Survey, Open-File Report 91-587B.