U. S. DEPARTMENT OF THE INTERIOR
U. S. GEOLOGICAL SURVEY
GEOLOGIC MAP OF SANTA CRUZ COUNTY, CALIFORNIA:
A DIGITAL DATABASE
Compiled by E. E. Brabb1
Digital Database Prepared by S. Graham, C. Wentworth, D. Knifong, R. Graymer and
J. Blissenbach
Open - File Report 97-489
This report is preliminary and has not been reviewed for conformity with U. S. Geological Survey editorial
standards. 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 "Geologic map of Santa Cruz County, 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.
1997
1Western Region Geologic Mapping Team, U.S. Geological Survey, 345 Middlefield Rd., MS 975, Menlo
Park, CA 94025
INTRODUCTION
This Open-File report is a digital geologic map database. This pamphlet serves to
introduce and describe the digital data. There is no paper map included in the Open-File
report. The report does include, however, a PostScript plot file containing an image of the
geologic map sheet with explanation.
This digital map database is prepared from a previously published map by Brabb (1989).
The geologic map database delineates map units that are identified by general age, lithology
and clast size following the stratigraphic nomenclature of the U. S. Geological Survey.
For detailed descriptions of the units, their stratigraphic relations and sources of geologic
mapping, consult the accompanying PostScript plot file (sc-sht1.ps), or the original
published paper map (Brabb, 1989). The scale of the source map limits the spatial
resolution (scale) of the database to 1:62,500 or smaller.
For those interested in the geology of Santa Cruz County who do not use an ARC/INFO
compatible Geographic Information System (GIS), but would like to obtain the paper map
with explanation, one PostScript plot file containing map images of the data in the
digital database, as well as a PostScript plot file of the explanatory text, have been included
in the database package (please see the section "PostScript Plot Files Package" page 5).
However, the plot files require gzip and tar utilities to access the files.
For those without computer capability, we have made the plot files available to an outside
vendor, or we can provide users with the PostScript plot files on tape that can be used by
other vendors (please see the section "Obtaining Plots from an Outside Vendor" page 5).
The content and character of the database and methods of obtaining it are described herein.
The geologic map database itself, consisting of two ARC coverages and one base layer,
can be obtained over the Internet or by magnetic tape copy as described below. The
processes of extracting the geologic map database from the tar file, and importing the ARC
export coverages (procedure described herein), will result in the creation of an ARC
workspace (directory) called 'scruz.'
The database was compiled using ARC/INFO, a commercial Geographic Information
System (Environmental Systems Research Institute, Redlands, California), with version
3.0 of the menu interface ALACARTE (Fitzgibbon and Wentworth, 1991, Fitzgibbon,
1991, Wentworth and Fitzgibbon, 1991). It is stored in uncompressed ARC export format
(ARC/INFO version 7.x) in a compressed UNIX tar (tape archive) file. The tar file was
compressed with gzip, and may be uncompressed with gzip, which is available free of
charge via the Internet from the gzip Home Page (http://w3.teaser.fr/~jlgailly/gzip). A tar
utility is required to extract the database from the tar file. This utility is included in most
UNIX systems, and can be obtained free of charge via the Internet from Internet
Literacy's Common Internet File Formats Webpage
(http://www.matisse.net/files/formats.html). ARC/INFO export files (files with the .e00
extension) can be converted into ARC/INFO coverages in ARC/INFO (see below) and can
be read by some other Geographic Information Systems, such as MapInfo via ArcLink and
ESRI's ArcView (version 1.0 for Windows 3.1 to 3.11 is available for free from ESRI's
web site: http://www.esri.com).
DATABASE CONTENTS
The first digital package consists of one PostScript plot file of the geologic map and
explanation and the geologic description. A second digital database package consists of the
geologic map database itself and the supporting data, including the base map, map
explanation, geologic description, and references.
POSTSCRIPT PLOTFILE PACKAGE
The first digital data package (sc-sht1.ps.gz) contains the PostScript image described
below:
sc-sht1.ps A PostScript plottable file containing an image of the geologic
map and base map of Santa Cruz County, including the
correlation chart, at a scale of 1:62,500.
DIGITAL DATABASE PACKAGE
The geologic map database consists of two layers and one base layer. Each of these layers
(coverages) has been converted to uncompressed ARC/INFO export files. The ARC
export files and the associated ARC/INFO coverages, as well as the additional digital
material included in the database package, are described below:
ARC/INFO Resultant Description of Coverage
export file Coverage
-------------- ------------ -----------------------------
sc-geol.e00 sc-geol Depositional contacts and unit labels
sc-strc.e00 sc-strc Fold axes, strike and dip information
sc-topo.e00 sc-topo Topographic base map taken from a scan of
U.S. Geological Survey, San Francisco Bay
Region, sheet 3, 1:125,000, 1970
ASCII text files and PostScript plot files:
scdb.txt This file
scdb.ps A formatted version of scdb.txt
import.aml ASCII text file in ARC Macro Language to convert these ARC
export files to ARC coverages in ARC/INFO
The following directory is produced in the process of converting the export files into ARC
coverages:
info/ INFO directory containing the database files that accompany each
ARC/INFO layer (coverage).
Once the ARC export coverages have been imported (see discussion below), the Santa
Cruz County (scruz) directory, or ARC workspace, will look like this:
scruz/
info/
sc-geol/
sc-strc/
sc-topo/
scdb.ps
scdb.txt
import.aml
OBTAINING PLOTS FROM AN OUTSIDE VENDOR
For those interested in the geology of Santa Cruz County who do not use computers, we
have made the PostScript plot file available to Capitol Color, 2250 Walsh Ave., Santa Clara
(phone: (800) 700-2656 or (408) 727-7560, FAX: (408) 727-0737). They will provide
plots of the PostScript image of the geologic map sheet for a fee (around $25 per sheet,
with discounts for orders of multiple copies). We will also provide the PostScript plot file
on digital tape for use by other vendors. A 7.5 MB compressed tar file (sc-sht1.tar.gz,
26.6 MB when uncompressed) of the PostScript plot files can be obtained by sending a
tape with request and return address to:
Santa Cruz County Geology PostScript Plotfile
c/o Database Coordinator
U.S. Geological Survey
345 Middlefield Road, MS 975
Menlo Park, CA 94025
The compressed plot file will be returned on the tape. The acceptable tape types are:
2.3 or 5.0 GB, 8 mm Exabyte tape.
Make sure your vendor is capable of reading these tape types and this PostScript plot file.
Important information regarding tape file format is included in the section "PostScript Plot
Files" below, so be certain to provide a copy of this document to your vendor.
POSTSCRIPT PLOTFILE PACKAGE
For those interested in the geology of Santa Cruz County who don't use an ARC/INFO
compatible GIS system, but would like to obtain the paper map with explanation, we have
included a separate data package (sc-sht1.ps.gz) with one PostScript plot file representing
the geologic data. This plot file contains a color plot of the geologic map database, map
key, and correlation chart at 1:62,500 scale (Sheet 1, sc-sht1.ps).
This plot file is available in any of the three ways described below, including the World Wide
Web pages. However, the plot file is stored in a compressed UNIX file requiring gzip to
access the file. The plot file was compressed with gzip, and may be uncompressed with
gzip, which is available free of charge via the Internet from the gzip home page
(http://w3.teaser.fr/~jlgailly/gzip).
The PostScript image of Sheet 1 is 60 inches wide by 36 inches high, so it requires a large
plotter to produce paper copies at the intended scale. Because this release is primarily a
digital database, the plot file (and plots derived therefrom) has not been edited to conform to
U.S. Geological Survey standards. Small units have not been labeled with leaders and in
some instances map features or annotation may overlap. Sample plots by the authors,
however, have proven to be quite legible and useful.
Obtaining the PostScript plotfile package
The PostScript plotfile package can be obtained in any of three ways:
1. Sending a tape with request
A 7.5 MB compressed plotfile can be obtained by sending a tape with request to:
Santa Cruz County Geology PostScript Plotfile
c/o Database Coordinator
U.S. Geological Survey
345 Middlefield Road, MS 975
Menlo Park, CA 94025
The compressed tar file will be returned on the tape. The acceptable tape types are:
2.3 or 5.0 GB, 8 mm Exabyte tape.
2. Anonymous ftp over the Internet
To obtain the tar file by ftp, log in to your UNIX system and do the following:
cd local_directory -go to a directory to receive the
tar file
ftp wrgis.wr.usgs.gov -make ftp connection with the
USGS computer WRGIS
Name: anonymous -use "anonymous" as your user
name
Password: your name -use your own user name as
password
cd pub/open-file -go down to the pub/open-file directory
cd of97-489 -go down to the open file directory
type binary -change transfer type to binary
get sc-sht1.ps.gz -copy the compressed plot file
across Internet to your directory
quit -close the ftp connection
3. From the Western Region Geologic Information Web Page.
The U.S. Geological Survey now supports a set of graphical pages on the World Wide
Web. Digital publications (including this one) can be accessed via these pages. The web
server for digital publications from the Western Region is "http://wrgis.wr.usgs.gov".
Once at the main page, click on 'Geologic Map Databases' under the heading 'Data Online';
next click on 'California.' Scroll down to the section for this database and click on the
Open-File button to get to this publication's web page. Or go directly to this publication's
web page: http://wrgis.wr.usgs.gov/open-file/of97-489. Set your web browser to save to
a local disk and click on the link labeled 'sc-sht1.ps.gz' to download the compressed plot
file that contains the Santa Cruz County map.
Extracting The PostScript Plotfile
1. If you obtained the plotfile package 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 being
an integer, this puts the tar file
in local_directory; 20 is the block size
of the tar file
gzip -d sc-sht1.ps.gz -makes a 26.6 MB uncompressed
plot file sc-sht1.ps
2. If you obtained the database by anonymous ftp or from the World Wide Web:
gzip -d sc-sht1.ps.gz -makes a 26.6 MB uncompressed
file sc-sht1.ps
OBTAINING THE DIGITAL DATA
The digital database package can be obtained in any of three ways:
1. Sending a tape with request
A 9.8 MB compressed tar file of the geologic map database and related files can be obtained
by sending a tape with request and return address to:
Santa Cruz County Geologic Database
c/o Database Coordinator
U.S. Geological Survey
345 Middlefield Road, M/S 975
Menlo Park, CA 94025
The compressed tar file will be returned on the tape. The acceptable tape types are:
2.3 or 5.0 GB, 8mm Exabyte tape.
2. Anonymous ftp over the Internet
To obtain the tar file by anonymous ftp do the following:
cd local_directory go to a directory to receive the tar
file
ftp wrgis.wr.usgs.gov make ftp connection with the USGS
computer WRGIS
Name: anonymous use 'anonymous' as your user name
Password: your email address use your email address as a
password
cd pub/geologic go down to the pub/geologic
directory
cd ca/of97-489 go down to the open file directory
type binary change transfer type to binary
get scruz.tar.gz copy the compressed tar file across
Internet to the receiving directory
quit close the ftp connection
3. From the Western Region Geologic Information Web Page.
To obtain the tar file via the World Wide Web:
The U.S. Geological Survey now supports a set of graphical pages on the World Wide
Web. Digital geologic publications (including this one) can be accessed via these pages.
The web page for digital geologic publications from the Western Region (including this
one) is Òhttp://wrgis.wr.usgs.govÓ. Once at the main page, click on 'Geologic Map
Databases' under the heading 'Data Online'; next click on 'California.' Scroll down
to get to the listing for this database. Click on 'Open-File Report 97-489'; this will
take you to the web page for this database. Set your web browser to save to a local disk
and click on the link labeled 'scruz.tar.gz' to download the compressed tar file that contains
the Santa Cruz County map database, or, select a single layer, layers or the PostScript plot
file (sc-sht1.ps.gz).
EXTRACTING THE GEOLOGIC MAP DATABASE FROM THE TAR FILE
If you obtained the database package 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; 20 is the block
size of the tar file
gzip -d scruz.tar.gz -makes a 36.3 MB uncompressed
tar file scruz.tar
cd local_directory2 -go to the directory that will hold
the directory scruz (if different
from local_directory)
tar xvfb {path to tar
file}/scruz.tar 20 -extract the scruz directory from
the tar file; 20 is the block size of
the tar file.
If you obtained the database package by anonymous ftp or from the web page:
gzip -d scruz.tar.gz -makes a 36.3 MB uncompressed
tar file scruz.tar
cd local_directory2 -go to the directory that will hold
the directory scruz (if different
from local_directory)
tar xvfb {path to tar
file}/scruz.tar 20 -extract the scruz directory from
the tar file.
Each of the processes described above will create a directory "scruz" that contains the ARC
export files and supporting files as described below. The directory structure at this
point will look like this:
scruz/
sc-geol.e00
sc-strc.e00
sc-topo.e00
scdb.ps
scdb.txt
import.aml
CONVERTING ARC EXPORT FILES
ARC export files are converted to ARC coverages using the ARC command IMPORT with
the option COVER. In order to ease conversion and to maintain naming conventions, we
have included an ASCII text file in ARC Macro Language that will convert all of the export
files in the database into coverages and create the associated INFO directory. Change
directories to the scruz/ directory. From the ARC command line type:
Arc: &run import.aml
ARC export files can also be read by some other Geographic Information Systems. Please
consult your GIS documentation to see if you can use ARC export files and the procedure
to import them.
DIGITAL COMPILATION
The geologic map information was digitized from a stable original of the geologic map at
1:62,500 scale. The author manuscript (ink on a greenline) was scanned using a
monochrome scanner with a resolution of 800 dots per inch. The scanned image was
vectorized and transformed from scanner coordinates to projection coordinates with digital
tics placed by hand at latitude/longitude intersections. The scanned lines were edited
interactively by hand using graphical user interface ALACARTE (Fitzgibbon, 1991,
Fitzgibbon and Wentworth, 1991, Wentworth and Fitzgibbon, 1991). Scanning artifacts
significant for display at a scale of 1:62,500 were corrected.
BASE MAP
The base map layer (sc-topo) was prepared by scanning a scale-stable clear film of the U.S
Geological Survey, San Francisco Bay Region, sheet 3, 1:125,000 (1970) topographic
map. The clear film was scanned using a monochrome scanner with a resolution of 400
dots per inch. The raster scan was converted to a GRID in ARC/INFO. The GRID was
then vectorized and reprojected into UTM Projection using the latitude/longitude
intersections as reference points. The arcs in the base layer have not been attributed. The
base map is provided for reference only.
SPATIAL RESOLUTION
Uses of this digital geologic map should not violate the spatial resolution of the data.
Although the digital form of the data removes the 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 edited at a scale of 1:62,500 means that higher resolution
information is not present in the dataset. Plotting at scales larger than 1:62,500 will 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 these data.
FAULTS
This database is not sufficiently detailed or comprehensive to identify or characterize site-
specific hazards represented by faults shown; the faults shown do not take the place of
fault-rupture hazard zones designated by the California State Geologist (see Hart, 1988).
DATABASE SPECIFICS
The map databases consist of ARC coverages which are stored in UTM projection (Table
1). Digital tics define a 2.5 minute grid of latitude and longitude in the geologic coverages
corresponding with the corners of the 7.5' quadrangles that fall within the county.
Table 1 - Map Projection
The map is stored in Universal Transverse Mercator projection
PROJECTION UTM
UNITS METERS -on the ground
ZONE 10 -UTM Zone 10
DATUM NAD27
PARAMETERS -none
The content of the geologic database can be described in terms of the lines and the areas that
compose the map. Descriptions of the database fields use the terms explained in 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,
I-ASCII integer, C-ASCII character string
N. DEC. number of decimal places maintained for
floating point numbers
LINES
The lines (arcs) are recorded as strings of vectors and are described in the arc attribute table
(Table 3). They define the boundaries of the map units, the boundaries of open bodies of
water, and the map boundaries. These distinctions, including the geologic identities of the
unit boundaries, are recorded in the LTYPE field according to the line types listed in Tables
4 and 5.
Table 3 - Content of the Arc Attribute Tables (SC-GEOL.AAT, SC-STRC.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 ofthe arc
RPOLY# 4 5 B polygon to the right of the arc
LENGTH 4 12 F 3 length of arc in meters
<coverage># 4 5 B unique internal control number
<coverage>-ID 4 5 B unique identification number
LTYPE 35 35 C line type (see Tables 4 and 5)
SEL 1 1 I user defined field used to save a
selected set
SYMB 3 3 I user defined field used to save symbol
assignments (such as color)
Table 4 - Line Types Recorded in the LTYPE Field (SC-GEOL)
contact, approx. located
contact, certain
contact, inferred
fault, approx. located
fault, certain
fault, concealed
map boundary, certain
scratch boundary
scratch boundary, countyline
water boundary
Table 5 - Line Types Recorded in the LTYPE Field (SC-STRC)
f.a., anticline, approx. located
f.a., anticline, certain
f.a., anticline, concealed
f.a., syncline, approx. located
f.a., syncline, certain
f.a., syncline, concealed
AREAS
Map units (polygons) are described in the polygon attribute table (Table 6) The identities of
the map units from compilation sources are recorded in the PTYPE field by map label
(Table 7). For a full description of the map units, consult the PostScript plot file (sc-
sht1.ps).
Table 6 - Content of the Polygon Attribute Tables (SC-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
<coverage># 4 5 B unique internal control number
<coverage>-ID 4 5 B unique identification number
PTYPE 35 35 C unit label (see Table 7)
SEL 1 1 I user defined field used to save
a selected set
SYMB 3 3 I user defined field used to save
symbol assignments (such as color)
Table 7 - Map Units (SC-GEOL)
Kcg Qof Tmm hcg Kgs Qt Tmp m
QTc Qtl Tms wf
Qae Qwf Tp qd
Qaf Qyf Tps sch
Qal Qyfo Ts
Qar Tbl Tsc
Qb Tblc Tsl
Qbs Tbm Tsm
Qce Tbs Tsr
Qcf Tbu Tst
Qcl Tl Tvq
Qcu Tla Tz
Qds Tlo db
Qem Tlss ga
Qes Tm gd
POINTS
Point information (strikes and dips) is recorded as coordinate and related information and is
described in the Point Attribute Table (Table 8). The identities of point types recorded in
the PTTYPE field of the SC-STRC.PAT table are shown in Table 9.
Table 8 - Content of the Point Attribute Tables (SC-STRC.PAT)
ITEM NAME WIDTH OUTPUT TYPE N. DEC
AREA 4 12 F 3 not used
PERIMETER 4 12 F 3 not used
<coverage># 4 5 B unique internal control number
<coverage>-ID 4 5 B unique identification number
PTTYPE 35 35 C point type (see Table 9)
DIP 3 3 I dip angle in degrees
STRIKE 3 3 I strike angle in degrees
SEL 1 1 I user defined field used to
save a selected set
SYMB 3 3 I user defined field used to
save symbol assignments
(such as color)
Table 9 - Point Types (SC-STRC)
approx dip of bedding
bedding
flat bedding
foliation
ot bedding
vert bedding
ACKNOWLEDGMENTS
I am most grateful to Joseph Clark, Indiana University, Pennsylvania, whose work forms
the core of the County geology, and whose continual interest provides a rich resource to
address unsolved problems. I am also grateful to William Dupre, University of Houston,
for his help with the Quaternary geology, and to Thomas Dibblee, Jr., retired, and Robert
McLaughlin for their work on the bedrock geology. Robert Smith kindly provided new
information on a strand of the San Gregorio fault. David Burky, Kristin McDougall,
William Sliter (deceased) and John Barron provided many identifications and ages for
microfossils in an area characterized by poor outcrops, several formations with similar
lithology, and complex structure.
REFERENCES
Brabb, E.E., 1989, Geologic map of Santa Cruz County, California: U.S. Geological
Survey Miscellaneous Investigations Series Map I-1905, scale 1:62,500.
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.
Hart, E.W., 1988, Fault-rupture hazard zones in California; Alquist-Priolo Special Studies
Zones Act of 1972 with index to special studies zones maps: California Division of
Mines and Geology Special Publication 42.
Wentworth, C. M., and Fitzgibbon, T. T., 1991, ALACARTE user manual (version 1.0):
U. S. Geological Survey Open-File Report 91-587C.