DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

GENERAL DISTRIBUTION OF GEOLOGIC MATERIALS 

IN THE SAN FRANCISCO BAY REGION, CALIFORNIA:

A DIGITAL MAP DATABASE

compiled by 

Carl M. Wentworth

based on the work of 

E.E. Brabb (1989), S.E. Ellen and C.M. Wentworth (1995),

and E.J. Helley and K.R. Lajoie (1979)

Open-File Report 97-744

1997

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 ’General Distribution of Geologic Materials in the San Francisco Bay Region, 

California: A Digital Map 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 digital map database, which is compiled from 1970’s sources, describes the general distribution 

and identity of geologic materials in the San Francisco Bay region, California (figure 1). Although 

based on the units distinguished on geologic maps, it is not itself a geologic map because it does not 

address geologic structure or the stratigraphic organization of the map units in a systematic way. Instead, it is directed at the distribution and physical character of the geologic materials, following the 

pattern of its progenitors, Wentworth and others (1985) and Ellen and Wentworth (1995). Consultation of these reports and the other compilation sources will aid in using the database. This report 

corrects some errors from and replaces the earlier digital map database represented by Open-File Report 93-693, which covered only the area of sheet 3 southwest of the Calaveras fault.

The materials database delineates map units that differ in physical properties, although the differences 

between many of the units may be small, depending on the properties of interest for any particular 

application. The materials units are categorized in the database by general age and lithology, by the 

geologic units that they represent, and by the map labels used in the compilation sources, which permit 

direct correlation with the unit descriptions of those sources. For all but the most general uses, the map 

Figure 1. Map showing the 10-county area covered by the database (within heavy boundary), the area 

of Santa Cruz County, and the three sheets (1-3) into which the topographic base (Aitken, 1997) is 

divided. The materials database combines the three separate sheets in which it was originally compiled 

plus the southwest quadrant, but retains the internal sheet boundaries.

123° 45’ 122° 37’ 30’’ 121° 30’

121° 07’ 30’’

38° 52’ 30’’

37° 52’ 30’’

Sheet 1

Sheet 2

Sheet 3

Santa Cruz Co.

SAN FRANCISCO

36° 52’ 30’’

Sheet 4

2
units will need to be assigned additional attributes, either from the unit descriptions in the compilation 

sources or by other means of characterization. The map scales of the sources limit the spatial resolution (scale) of the materials database to 1:125,000 or smaller. The database is thus 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 materials database was compiled over a period of several years with versions 4 through 7.0.4 of 

ARC/INFO, a commercial Geographic Information System (Environmental Systems Research Institute [ESRI], Redlands, California) on a UNIX computer using the menu interface ALACARTE 

(versions 1 through 3.1: Fitzgibbon and Wentworth, 1991; Fitzgibbon, 1991; Wentworth and Fitzgibbon, 1991). 

The report consists of two spatial databases, each of which covers the whole region (the materials 

database and a database of 7.5-minute quadrangles), a map (as a digital map image) entitled "Geologic 

Materials of the San Francisco Bay Region", and supporting files. The map, at a scale of 1:275,000, 

was prepared from the materials database and combines the 377 materials units into 45 categories 

based on general age and lithology; it is only one of many maps that can be prepared from the 

database.

The report is stored as several digital files, including for the spatial data both ARC export (uncompressed) and ARCVIEW shape formats and for the map image both Postscript and PDF formats. The 

exported ARC coverages are in UTM zone 10 projection and the shape versions are in decimal 

degrees. This pamphlet, which simply describes the content and character of the digital map database, 

is included as both postscript and ASCII text files and is also available on paper as USGS Open-File 

Report 97-744. A plotted copy of the map can be ordered from a USGS Earth Science Information 

Center or by phone at 1-800-USMAPS (this service should become available sometime in 1999). Any 

or all of the digital files can be obtained over the Internet or by magnetic tape copy, as described 

below. 

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, 

can use either the ARC export or shape files. The Postscript map image can be used for viewing or 

plotting in systems with sufficient capacity, and the considerably smaller PDF image file can be 

viewed or plotted in full or in part from Adobe ACROBAT running on Mac, PC, or UNIX platforms.

A digital version of the topographic base on which the materials map was compiled (U.S. Geological 

Survey, 1970), consisting of five vector layers (index contours, intermediate contours, drainage, culture, and detailed roads) for each of the three sheets (figure 1), is separately available as ARC export 

files in UTM zone 10 projection (Aitken, 1997). 

OBTAINING THE DIGITAL DATA

The database and image files can be downloaded from the Western Region Geologic Information 

Server Web page or by anonymous ftp over the Internet, or can be obtained by submitting a tape on 

which requested files will be copied and returned.

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Some of the files are assembled as 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.

The necessary utilities 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

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/: 

DATABASE CONTENTS

The report consists of digital files representing the five parts of the database, some of which are presented in more than one format. The names of the files are unique designators based on the report 

identifier, of97-744, followed by part numbers and an extension indicating file type. Some of the files 

have been bundled in tar files (.tar extension) and the ARC/INFO files and shape files have been 

separately packaged in tar files that 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 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. of97-744revs_a.txt ASCII file 

 2. Open File Text: The text of the open-file pamphlet (this text), which describes the database and 

how to obtain it. The ASCII version does not contain the index map (figure 1).

 a. of97-744_2a.txt ASCII file, 0.07 MB. 

 b. of97-744_2b.ps Postscript file, 0.33 MB 

 c. of97-744_2c.pdf PDF file, 0.07 MB 

 3. Materials Database: The data files representing the lines and polygons of the materials map and 

a supplementary file listing the map units (ARC export and ARCVIEW shape formats); some 

supporting files for use in ARC/INFO are also included.

a. of97-744_3a.e00 -- ARC export coverage containing both lines and polygons (39.5 MB). 

Import.aml will name this coverage sf-mtls.

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b. of97-744_3b.e00 -- ARC export INFO table that lists the geologic units in each materials 

unit (0.02 MB). Import.aml will name this table UNITS. 

c. of97-744_3c.tar -- Supporting files for ARC/INFO use, bundled as one tar file (0.01 MB). 

When opened, the tar file yields:

- UNIT.REL, an INFO relate file that relates polygons in the materials map to 

the units table.

- utm2lam.prj and lam2utm.prj: projection files to convert between the UTM 

zone 10 projection of the database and the native Lambert projection of the 

topographic base on which the materials map and its sources were compiled.

- import.aml: an ASCII script written in Arc Macro Language that can be used 

to convert the ARC export files into usable coverages and INFO files that are 

assigned standard names (see IMPORTING THE ARC EXPORT FILES). 

d. of97-744_3d.tar -- Line and polygon ARCVIEW shape files bundled as one tar file (45.5 

MB). When opened, the tar file yields:

- line files mtllns.dbf, mtllns.shp, and mtllns.shx

- polygon files mtlpys.dbf, mtlpys.shp, and mtlpys.shx

e. of97-744_3e.dbf -- DBase table that lists the geologic units in each materials unit (0.05 

MB). 

 4. 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. of97-744_4a.e00 -- ARC export coverage containing lines, polygons, and annotation (1.1 

MB). Import.aml will name this coverage sf-qdgrid. 

b. of97-744_4b.tar -- Line and polygon ARCVIEW shape files bundled as one tar file (1 

MB). When opened, the tar file yields:

- line files grdlns.dbf, grdlns.shp, and grdlns.shx

- polygon files grdpys.dbf, grdpys.shp, and grdpys.shx

 5. Plot File for the Map: Geologic Materials of the San Francisco Bay Region, delineated in terms 

of lithology and geologic age -- map image measures 34 by 33 inches when plotted.

a. of97-744_5a.ps.gz Postscript file ( 27.7 MB compressed to 5.8 MB)

b. of97-744_5b.pdf PDF file (5.3 MB)

Presentation

Some of the database files are provided separately and some are packaged together in tar files.

Separate Files: The revision list (of97-744revs_a.txt) and the three versions of the Open-File text 

(of97-744_2a.txt, of97-744_2b.ps, of97-744_2c.pdf) are provided separately, 

together with an abbreviated version of the ASCII text version as a README.

of97-744-arcfiles.tar.gz: The ARC export coverages (of97-744_3a.e00, of97-744_4a.e00), Units 

INFO file (of97-744_3b.e00), and tar file containing projection files and 

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import.aml (of97-744_3c.tar) are packaged together in a single gzipcompressed tar file. The 8.8 gz file unzips to a 40.7 MB tar file.

of97-744-shapefiles.tar.gz: The tar file of ARCVIEW shape files (of97-744_3d.tar, of97-

744_4b.tar) and units database (of97-744_3e.dbf) are packaged together in a 

single gzip-compressed tar file. The 12.7 MB gz file unzips to a 46.4 MB tar 

file.

REVISIONS

Changes to any parts of the report (the numbered items described above and listed in the revision list 

of97-744revs_a.txt) may be made in the future if needed. These could involve, for example, fixing 

files that don’t work, correcting geologic details, or adding new file formats or other components. 

Major revision of the basic geologic information would result in a new report.

The report begins at version 1.00. Any revisions will be noted 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 Server 

(see next section).

OBTAINING THE DATA FILES

The simplest way to obtain the database is to download it over the World Wide Web from the USGS 

Western Region Geologic Information Server:

http://wrgis.wr.usgs.gov

From the main page, click on ’Geologic map databases’ under the heading ’Data On-line’; next click 

on ’California’. Scroll down to the listing for this database (Open File Report 97-744) and click on the 

Open-File button, which takes you to the page for this publication. You can also go directly to that 

final page at: 

http://wrgis.wr.usgs.gov/open-file/of97-744

On this page, the several parts of the report in their different file types are separately available. Set you 

web browser to save to a local disk and click on the appropriate links to download the desired files.

To download the files across the net via anonymous ftp:

ftp wrgis.wr.usgs.gov - make ftp connection with the USGS computer wrgis.

Name: anonymous - enter "anonymous" as your user name.

Password: [your address] - enter your own email address as password.

cd pub/open-file - go down to the pub/openfile directory on wrgis.

cd of97-744 - go down to the open file directory for this report on wrgis.

type binary - change transfer type to binary.

ls - list the available files, if necessary.

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get [file name] - download each of the desired files separately with the ftp "get" 

command.

quit - close the ftp connection

To obtain files from the database on magnetic tape, send a tape with your request specifying the 

desired files and your return address to:

San Francisco Bay Geologic Materials Database

c/o Database Coordinator 

U.S. Geological Survey

345 Middlefield Road MS 975

Menlo Park, CA 94025

The specified files bundled in a compressed tar file will be returned to you on the tape. The acceptable 

tape types are:

2.3 or 5.0 GB, 8 mm Exabyte tape

OPENING THE DATABASE FILES

For those database files that are provided in compressed form and/or are bundled in a tar file, preliminary processing is required before the files are accessible by your GIS or image applications.

Compressed Gzip Files

Files compressed with gzip (those with a .gz extension) can be uncompressed with gzip:

gzip -d [file name] - converts the compressed file name.gz to its uncompressed equivalent 

name. The compressed file is replaced by the uncompressed file.

Tar Files

To extract the contents of a tar file, first uncompress it with gzip if the extension is .tar.gz. Once the 

tar extension is exposed, extract the contents with tar:

tar xvf [name].tar - extract the contents from the tar file. The contained files will be written to the current directory; the source tar file will not be changed.

IMPORTING THE ARC EXPORT FILES 

The ARC export files (__.e00) can be converted to ARC/INFO vector maps (coverages) and INFO 

files by running the import.aml that is included in the database. This will import the export files, assign 

standard names (see below), build the polygon coverages (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 denied, but 

will not interfere with the results of earlier runs. The aml 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:

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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 and separate INFO files will be given standard names:

of97-744_3a.e00 (Geologic Materials Database) is named sf-mtls

of97-744_3c.e00 (INFO units table) UNITS

unit.rel.e00 (INFO relate file from of97-744_3e.tar) UNIT.REL

of97-744_4a.e00 (Quadrangle Index Database) sf-qdgrid

 

 

DIGITAL COMPILATION

The materials spatial database was compiled on a 1:125,000 topographic base (U.S. Geological Survey, 1970; Aitken, 1997) from three regional compilations of 1970’s data. Two of the sources were 

photomechanically compiled in the 1970’s on this same base and address the surficial deposits (flatland deposits: Helley and others, 1979) and the bedrock (hillside materials: Ellen and Wentworth, 

1995) of the 9-county San Francisco Bay region. (The San Mateo County part of the hillside materials 

map is based, in turn, on Wentworth and others, 1985). The separate geologic map of Santa Cruz 

County (Brabb, 1989), also based largely on 1970’s and older data, was compiled on the same base 

photo-enlarged to a scale of 1:62,500. For the present digital compilation, inked or scribed linework 

for each of these sources was scanned (400 or more dots per inch), converted from raster to vector 

form, imported into ARC/INFO, and hand edited and combined into a single coherent map. 

Digital compilation began with preparation of digital versions of the sources. The original material 

used to digitize linework for the surficial deposits was author manuscript (ink on mylar) and for the 

hillside materials and Santa Cruz County geologic maps was digital print-publication files (prepared 

for color separation by scribing and scanning) together with scribed or drafted fault plates that were 

then separately scanned, edited, and vectorized. The faults and color boundaries were combined interactively by hand for each source separately using ALACARTE, with the color boundaries attributed 

as contacts or replaced by faults, as appropriate. The fault plate for Santa Cruz County required a slight 

xy shift and rotation in the computer to produce a reasonable fit with the color boundaries. 

Combining the surficial and hillside maps involved much adjustment of common boundaries and, in 

many places, the creation of an intervening map unit (PTYPE1

 = 20) to occupy the space between the 

downslope margin of mapped bedrock and the upslope margin of mapped surficial deposits, as well as 

to represent unidentified islands within mapped surficial deposits. In the simplest case, a gap between 

surficial deposits and bedrock represents colluvium, but this new unit also includes areas of unmapped 

__________________________________________________________________

1 See Database Specifics below for explanation of the database fields shown in capital letters.

8
Quaternary deposits, some quite large areas of possible bedrock with very subdued topography, and 

mapped colluvium in Santa Cruz County. 

Scanning artifacts significant for display at a scale of 1:125,000 were corrected and some surficial 

boundaries were adjusted to better fit the base. The boundary of Santa Cruz County is included in the 

map to retain the integrity of units on either side and because of misfits across that boundary, which 

result from different sources and compilation objectives in the three compilation sources. Small adjustments were made to fit lines across the boundary, but larger misfits were retained. The detail of 

the Santa Cruz County geologic map has not been simplified to match the higher level of generalization of the surficial and hillside maps: a few geologic corrections have been made to lines and unit 

identities relative to the published map in consultation with E.E. Brabb.

The geologic identities of lines specified in the LTYPE field are largely those of the compilation 

sources, except that all contacts from the surficial map are coded as approximately located. Long 

reaches of concealed faults are not included.

The materials data were initially compiled as three separate sheets (sheets 1-3, fig. 1), and the outline 

of a fourth sheet was created to fill the southwest quadrant of the region (entirely water). When complete, these four sheets were combined into a single layer (coverage) and numerous small boundary 

misfits inherent in the source materials were adjusted; the internal boundaries of the original sheets 

were retained.

MATERIALS UNITS

The spatial database shows the distribution of 375 materials units, 17 surficial and 358 bedrock, as 

well as open water and the unmapped portions of the three compilation sheets. The primary unit 

identifier is an integer in the character field PTYPE (and its numeric equivalent NPTYPE), which 

ranges from -1 to 911. The numbering is not continuous because of the assignment of PTYPEs by 

categories according to the general character of the units (see Table 1).

 The PTYPE organization of the materials units is based on the hillside map units of Ellen and Wentworth (1995) and of Wentworth and others (1985), which are organized by such physical properties as 

lithology, bedding, hardness, and fracture spacing. These categories range from subdivisions of 

mapped rock units to composites of several rock units (the latter particularly in San Mateo County). 

Here this scheme is extended to encompass all the units in the map area by (1) correlating the bedrock 

units in Santa Cruz County with hillside units to the northwest and east according to Brabb’s unit 

descriptions, and (2) erecting new categories for the surficial units. Each PTYPE unit is relatively 

homogeneous in its range of physical properties (or at least in its degree or kinds of heterogeneity) and 

can be characterized by reference to the compilation sources or other observations. NPTYPEs less 

than 99 are surficial deposits and greater than 98 are bedrock units, including semiconsolidated PlioPleistocene deposits. The categorization of bedrock materials is described in the map explanations and 

Table 5 of Ellen and Wentworth (1995) and is summarized in Table 1 below. 

Table 1. General PTYPE Categories

Descriptions of hillside materials categories are modified from Table 5 of Ellen and Wentworth (1995)

-1 - unmapped areas outside the 10-county region

0 - open water

9
1-19 - Holocene surficial deposits

20-70 - Pleistocene and undivided Quaternary surficial deposits

99 & 100’s - soft sandstone, conglomerate, and clayey rock - largely Pliocene and Pleistocene deposits, 

including Santa Clara, Merced, and Tehama formations.

200’s - volcanic rock - largely Sonoma Volcanics, Miocene basalts, tuffs, and Franciscan greenstone.

300-400’s - firm sandstone and clayey rock - Tertiary sedimentary rocks, such as Briones and Neroly 

formations.

500’s - siliceous rock - Mesozoic and Tertiary siliceous rocks, such as Franciscan chert and Claremont Shale.

600’s - well-bedded, hard-firm sandstone and clayey rock - largely units of the Mesozoic Great 

Valley sequence.

700’s - deformed hard sandstone and clayey rock - Franciscan sandstone.

801-804 - mixed clayey sheared rock and masses of fractured hard rock - Franciscan melange and 

variably sheared Franciscan metagreenstone.

805 - sheared serpentinite.

900’s - hard homogeneous rock - granitic rock, diabase, and unsheared ultramafic rock.

PTYPE 20 is used to represent the unclaimed areas between surficial and hillside units that are too 

large to accommodate with a compromise common boundary, as well as most unmapped islands 

within mapped surficial deposits. PTYPE 21, in contrast, is used for (1) areas that are mapped as 

Quaternary deposits in the geologic sources for the hillside map but are not so shown on the surficial 

deposits map (Helley and others, 1979), (2) areas mapped as undivided Quaternary deposits (Qu) on 

the surficial deposits map, (3) some locally unidentified bedrock islands within mapped surficial deposits on sheet 3 and, south of Half Moon Bay and northwest of Santa Cruz County, and (4) the 

simplified surficial unit (UNIT = S) of Wentworth and others (1985) that is used here instead of the 

very intricate units of Helley and others (1979).

The NPTYPE field of the materials map database, values of which are numeric equivalents of the 

PTYPE character values, is included to permit database searches by ranges of NPTYPE. PTYPE is 

used as the principal unit identifier for compatibility with ALACARTE.

The physical properties of the map units are not described in detail in this report (see the unit descriptions in the compilation sources), but the units are categorized by general lithology (LITH) and 

age (AGE). Because the degree of consolidation or hardness of sedimentary geologic materials in the 

region typically increases with age, lithology and age together (AGELITH) provide a good first approximation of physical character. Note that some units do not easily fit into these categories, 

particularly because their age or lithology straddles the category boundaries. 

The identities of the map units in the compilation sources are recorded in the UNIT database field by 

their map labels (numbers for the hillside materials map, conventional geologic labels for the surficial 

deposits and Santa Cruz County geologic maps). Only selected large landslides are included except in 

San Mateo County, where all the larger landslides and their bedrock identities are included (Wentworth and others, 1985). Geologic unit identities of the materials units reported in the compilation 

sources are recorded in the separate database table UNITS and in Appendix 1 as an aid in characterizing the units. A database relate named UNIT.REL is included to support queries in ARC/INFO about 

geologic units from within the spatial database to the UNITS table as a function of NPTYPE 

(unit.rel//geolunit). 

10
FAULTS AND LANDSLIDES

Faults are distinguished in the database only as part of the physical character of the geologic materials 

and the database cannot be used to identify or delineate active faults in the region. Similarly, the 

database cannot be used to identify or delineate most landslides in the region. Larger landslides are 

included as part of the physical character of the materials in San Mateo County, but only those large 

landslides for which bedrock identity is uncertain are shown elsewhere in the region.

SPATIAL RESOLUTION

Uses of this digital map 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 at a scale of 1:125,000 (1:62,500 in Santa Cruz County) means that higher resolution 

information is not present in the database. Use of the database at scales larger than 1:125,000 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 this data. 

MAP OF AGE/LITHOLOGY CATEGORIES

A map image at a scale of 1:275,000, stored both as a postscript file (of97-744_5a.ps) and a PDF file 

(of97-744_5b.pdf), is included to show the general content of the materials database. It was assembled 

in UTm zone 10 projection, and includes the drainage base layer (Aitken, 1997). Map units are organized according to the 45 AGELITH categories of the materials units and geologic lines are 

symbolized as a function of the LTYPE values, using the ALACARTE lineset GEOLOGY.LIN and 

lookup table GEOLINE.LUT. Latitude-longitude tics at an interval of 7.5 minutes are included from 

the coverage sf-qdgrid by selecting and plotting arcs therein shorter than 550 m. This map is only one 

of many that can be prepared from the database, depending on how the units are characterized and 

aggregated. The scale of 1:275,000 (much smaller than the full resolution of the database) was selected 

to fit the map onto 36-inch-wide plotter paper.

SPECIFICS OF THE MATERIALS DATABASE

The materials spatial database itself consists of the data layer sf-mtls (ARC coverage), its supporting 

INFO files, and the INFO table named UNITS. The map layer is stored in UTM projection (zone 10) 

(see Table 2) and projection files are included to convert between that and the Lambert projection of 

the source maps. Digital tics define a 7.5 minute grid of latitude and longitude (and see 7.5 MINUTE 

QUADRANGLE GRID, below). The content of the map database can be described in terms of the 

lines and areas that compose it. Descriptions of the database fields use the terms of Table 3.

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Table 2. Map Projection

projection utm (Universal Transverse Mercator)

units meters

zone 10

Table 3. 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

Lines - The lines (arcs) are recorded as strings of vectors with characteristics that are described in the 

arc attribute table (see Table 4). They define the boundaries of the map units, the boundaries of open 

bodies of water, the map and internal sheet boundaries, scratch boundaries, and part of the boundary 

of Santa Cruz County. These distinctions, including the geologic identities of the unit boundaries, are 

recorded in the LTYPE database field according to the line types listed in Table 5. The compilation 

sources of the lines are recorded in the SOURCE field (see Table 6). Note that the lines that separate 

surficial and bedrock units outside Santa Cruz County, regardless of the specified source (1 or 2), have 

been modified to accommodate the gap between the two in the compilation sources, except where the 

gap was so large (typically greater than 80-100 m) that an area of PTYPE = 20 was defined.

Table 4. Content of the Arc Attribute Table (SF-MTLS.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

SF-MTLS# 4 5 B - unique internal control number

SF-MTLS-ID 4 5 B - unique identification number

LTYPE 35 35 C - line type

SOURCE 2 2 I - compilation source of line

Table 5. Line Types Recorded in the LTYPE Field

The geologic line types (exclusive of the various 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.

contact, certain fault, inferred, queried

contact, approx. located fault, concealed

contact, inferred county boundary

12
contact, inferred, queried scratch boundary

contact, concealed water boundary

fault, certain sheet boundary

fault, approx. located map boundary

Table 6. Sources of the Lines

The compilation sources of the lines are recorded in the SOURCE field by numeric codes that indicate the 

following sources:

 CODE SOURCE

1 Helley and others, 1979

2 Ellen and Wentworth, 1995

3 Brabb, 1989

4 water boundaries extracted from the vectorized base scan (Aitken, 1997)

5 county boundaries extracted from the vectorized base scan (Aitken, 1997)

Areas - The materials map units are recorded as vector polygons with characteristics that are described in the polygon attribute table (see Table 7). The primary unit identifier is PTYPE (and its 

numeric equivalent, NPTYPE). The UNIT database field contains the map labels used in the compilation sources, and the AGE, LITH, and AGELITH fields contain the general age and lithology 

categories to which the materials units are assigned. Landslides are indicated by a value of LS in the 

LSLIDE and UNIT fields and, outside of San Mateo County, by PTYPE and NPTYPE = 70 and a 

LITH value of ld. Within San Mateo County, the landslides are assigned PTYPE, AGE, and LITH 

values according to the bedrock unit of which they are composed (after the usage of Wentworth and 

others, 1985), and their identity as landslides is indicated by a value of LS in the LSLIDE field. Those 

polygons located within Santa Cruz County are indicated by a COUNTY value of 1 (otherwise 0). 

Table 7. Content of the Polygon Attribute Table (SF-MTLS.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

SF-MTLS# 4 5 B - unique internal control number

SF-MTLS-ID 4 5 B - unique identification number

PTYPE 35 35 C - materials category

NPTYPE 4 4 I - numeric PTYPE

LSLIDE 35 35 C - landslide = LS

UNIT 35 35 C - unit label from compilation source 

COUNTY 1 1 I - = 1 in Santa Cruz Co., otherwise 0

AGE 3 3 C - age category

LITH 3 3 C - lithology category

AGELITH 7 7 C - combinations of AGE and LITH

13
Some special cases should be noted:

Some Tertiary materials units consisting of more than one age of geologic unit are subdivided by 

assigning different AGE values (Tu and Tl) to different polygons of the unit (see Appendix 1).

Some very small island polygons in sheet 3 within mapped surficial deposits that have no mapped 

identities are assigned a UNIT value of br (possible bedrock), but are included in PTYPE = 20, 

undifferentiated and unmapped Quaternary deposits. 

Two of the many dams in the region are mapped and assigned UNIT = dam, but the remaining 

materials attributes are those of the underlying (surrounding) bedrock materials unit.

UNIT hcg in Santa Cruz County, which is gabbro, is assigned LITH = gr and is included in PTYPE 

= 907.

Table 8. Age Categories

 CODE AGE

 h Holocene

 p Pleistocene

 Q Quaternary undivided

 QT Pliocene and/or Quaternary

 Tu upper Tertiary

 Tl lower Tertiary

 Mz Mesozoic

 Table 9. Lithology Categories

 CODE LITHOLOGY

 ab agglomerate, breccia

 bv mafic volcanic rocks

cs clay, silt, sand, gravel

dm diatomite, diatomaceous shale, some sandstone

 fv felsic volcanic rocks

 gr granitic rock

hg high-grade metamorphic rocks

ld landslide

 ls limestone 

 m mud and silt

 md mudstone and shale, some sandstone

 mm sheared sandstone and shale (melange)

 ms low-grade metasandstone and shale

 mv low-grade metavolcanic rocks (greenstone)

 s sand, gravel, silt, and mud

 sc silica-carbonate rock

 sch schist

 sl porcelaneous or siliceous mudstone and shale; chert

 sm sandstone and mudstone or shale 

 sp serpentinite

 

14
ss sandstone and conglomerate, some mudstone or shale

tf tuff, tuffaceous sandstone, some sandstone, volcanic rock

wm soft, water-saturated mud, some silt

wt welded tuff

Table 10. Age and Lithology Combinations

 CODE AGE LITHOLOGY

 Holocene

h-wm soft, water-saturated mud, some silt

 h-m mud and silt

 h-s sand, gravel, silt, and mud

Pleistocene

p-s sand and gravel

 p-md mudstone and shale, some sandstone

p-ss sandstone, some mudstone 

QUATERNARY 

 Q-cs clay, silt, sand, gravel

 Q-s sand, gravel, silt, and mud

 Q-ld landslide

Q-ab agglomerate, breccia

PLIOCENE and/or QUATERNARY

QT-md mudstone, some sandstone

QT-sm sandstone and mudstone

 QT-ss sandstone, some mudstone 

 QT-tf tuff, tuffaceous sandstone, some sandstone, volcanic rock

 QT-fv felsic volcanic rocks

QT-bv mafic volcanic rocks

 UPPER TERTIARY

Tu-md mudstone and shale, some sandstone

 Tu-sl porcelaneous and siliceous mudstone and shale

 Tu-sm sandstone and mudstone or shale

 Tu-ss sandstone, some mudstone or shale

 Tu-ls limestone 

Tu-dm diatomite, diatomaceous shale, some sandstone

 Tu-tf tuff, tuffaceous sandstone, some sandstone, volcanic rock

 Tu-wt welded tuff

Tu-ab agglomerate, breccia

Tu-fv felsic volcanic rocks

Tu-bv mafic volcanic rocks

 Tu-sc silica-carbonate rock

15
LOWER TERTIARY

Tl-md mudstone and shale, some sandstone

Tl-sm sandstone and mudstone or shale

Tl-ss sandstone, some mudstone or shale 

 Tl-tf tuff, tuffaceous sandstone, some sandstone, volcanic rock

Tl-fv felsic volcanic rocks

MESOZOIC 

Mz-md mudstone and shale

 Mz-sm sandstone and shale

 Mz-ss sandstone and conglomerate, some shale

Mz-mm sheared sandstone and shale (melange)

 Mz-ms metasandstone, some shale

Mz-mv metavolcanic rocks (greenstone)

Mz-sl chert

Mz-ls limestone

Mz-bv mafic volcanic rocks

 Mz-fv felsic volcanic rocks

Mz-sp serpentinite

Mz-sch schist and marble 

Mz-gr granitic rock

 Mz-hg high-grade metamorphic rocks

Geologic Units - The geologic units included in each of the materials units are listed in Appendix 1 

and in the INFO table UNITS. This table contains the database field GEOLUNIT, in which the geologic units are listed (see Table 11), and a relating field NPTYPE. These geologic units range from 

rock types to formal stratigraphic names, as shown in the compilation sources. The UNITS table can 

be used directly in ARC/INFO or by relating from polygons in the materials data layer by way of 

NPTYPE to GEOLUNIT values in the table using the relate UNIT.REL (unit.rel\\geolunit).

Table 11. Table of Geologic Units

 ITEM NAME WIDTH OUTPUT TYPE N.DEC

NPTYPE 4 4 I - NPTYPE in the polygon attribute table 

GEOLUNIT 125 125 C - geologic units included in the materials unit

Tics - The digital tics in the materials data layer sf-mtls define a regular grid of 7.5 minute latitude/longitude intersections. The four corner tics are numbered 1 through 4 clockwise starting at the 

southeast corner (see figure 1 for latitude/longitude values), with the rest numbered in sequence from 

left to right and top to bottom. Four tics near or at the outer corners of each individual sheet (figure 1) 

were used to register the base layers with the surficial deposits and hillside materials sources. Similarly, four tics near the outer corners of the Santa Cruz County geologic map were used to register that 

map with the materials compilation.

16
7.5-MINUTE QUADRANGLE GRID

A separate vector layer of the map area (sf-qdgrid) contains 7.5 minute quadrangle boundaries and 

names. The grid of 7.5-minute lines of latitude and longitude and the intervening polygons define the 

quadrangles, and the quadrangles are named both in the NAME field of the polygon database and as 

diagonal (quad-centered, level 2) and horizontal (upper left, level 3) annotation. The lines are split 

around the quadrangle corners such that selection of arcs with length less than 550 m yields 7.5 minute 

latitude/longitude graphic tics 1000 m in diameter. Line attributes permit further distinction. The 

LTYPE field distinguishes the 15 minute quadrangle boundaries (LTYPE = ’15’) from the intervening 

7.5 quadrangle boundaries (LTYPE = ’7.5’). The southern and western sides of the odd-shaped Santa 

Cruz 7.5 quadrangle are included with LTYPE = ’santa cruz’. A separate TICS field similarly distinguishes the 15 minute graphic tics (TICS = ’15’) from the intervening 7.5 minute tics (TICS = ’7.5’). 

(Note that these latitude/longitude tics defined by lines are different than the standard digital tics of the 

database, which are also located at the 7.5 minute intersections.)

This quadrangle grid can be used to obtain latitude/longitude tics in plotting, for plotting of quadrangle 

boundaries and names, and for queries involving quadrangle identities. The quadrangle polygons can 

also be used to record information by quadrangle (after adding appropriate database fields).

ACKNOWLEDGMENTS

Compilation of the digital database was greatly facilitated by contributions from others. E.J. Helley 

provided author linework of the surficial deposits map for scanning. D.S. Aitken provided access to a 

digital version of the color boundaries for the geologic map of Santa Cruz County and scanned and 

vectorized the fault plates for that map and for the hillside materials map. N.L. Hoskin provided 

access to working digital files of the color boundaries and polygon tags being prepared for publication 

of the hillside materials map. S.D. Ellen and E.E. Brabb shared their geologic expertise about the 

region.

T.T. Fitzgibbon provided advice and assistance in the use of ALACARTE-ARC/INFO at the beginning of the project, T.M. Mahony prepared preliminary digital versions of much of the flatlands 

deposits, and D.L. Knifong assigned UNIT values to the polygons for the Santa Cruz geologic map. 

Other GIS assistance was provided by T.J.Felger, S.E. Graham, and P.K. Showalter. 

REFERENCES CITED

Aitken, D.S., 1997, Digital version of the topographic map of the San Francisco Bay Region, three 

sheets, 1:125,000: U.S. Geological Survey Open-File Report 97-500.

Brabb, E.E., 1989, Geologic map of Santa Cruz County, California: U.S. Geological Survey Miscellaneous Investigations Map I-1905, map scale 1:62,500.

Ellen, S.D., and Wentworth, C. M., 1995, Hillside materials and slopes of the San Francisco Bay 

Region, California: U.S. Geological Survey Professional Paper 1357, map scale 1:125,000.

Fitzgibbon, T.T., 1991, ALACARTE installation and system manual (version 1.0): U.S. Geological 

Survey, Open-File Report 91-587B.

17
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.

Helley, E.J., Lajoie, K.R., and others, 1979, Flatland deposits of the San Francisco Bay Region, California -- their geology and engineering properties, and their importance to comprehensive planning: 

U.S. Geological Survey Professional Paper 943, map scale 1:125,000.

Wentworth, C.M., Ellen, S.D., Frizzell, Jr., V.A., and Schlocker, Julius, 1985, Map of hillside materials and description of their engineering character, San Mateo County, California: U.S. Geological 

Survey, Miscellaneous Investigations Map I-1257D, map scale 1:62,500.

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

U.S. Geological Survey, 1970, [topographic map of the] San Francisco Bay Region, 3 sheets, map 

scale 1:125,000.

Appendix 1. Summary Descriptions of the Materials Units

 Units are listed by PTYPE, with equivalent AGELITH values from the map PATs and GEOLUNIT values 

from the INFO table UNITS. For some units, multiple AGE or LITH values are listed, because of differences 

within the materials unit. See Ellen and Wentworth (1995) for cited references.

 PTYPE: AGELITH Geologic Unit (GEOLUNIT)

-1: unmapped area

0: open water

1: h-wm Holocene Bay Mud (Qhbm)

2: h-m fine-grained Holocene alluvium (Qhaf)

3: h-m fine-grained salt-affected Holocene alluvium (Qhafs)

10: h-s Holocene beach and dune sand

11: h-s medium-grained Holocene alluvium (Qham)

12: h-s coarse-grained Holocene alluvium (Qhac)

13: h-s Holocene stream-channel deposits (Qhsc)

20: Q-cs undiv. and unmapped Quaternary deposits including colluvium between surficial 

deposits and hillside materials

21: Q-s undiv. mapped Quaternary deposits: alluvium terrace deposits Millerton Fm undivided Quaternary and some bedrock islands

30: p-s late Pleistocene alluvium (Qpa)

31: p-s Colma Fm (Qpmc)

32: p-s Merritt Sand (Qps)

33: p-s eolian deposits of Sunset Beach and of Manresa Beach and eolian lithofacies of 

Aromas Sand

35: p-s Pleistocene marine terrace deposits (Qpmt)

40: p-s Early Pleistocene alluvium (Qpea)

70: Q-ld landslide deposit

99: QT-ss undiv. nonmarine sand and silt

100: QT-ss gravel deposits

101: QT-ss Santa Clara Fm undiv.

102: QT-ss Corte Madera facies of Santa Clara Fm

103: QT-ss Arastradero facies of Santa Clara Fm

104: QT-ss Woodside facies of Santa Clara Fm

105: QT-ss Stevens Creek facies of Santa Clara Fm

18
106 QT-ss Los Gatos facies of Santa Clara Fm

107: QT-ss Searsville facies of Santa Clara Fm

108: Tu-ss conglomerate member of Ohlson Ranch Fm of Higgins (1960)

110: Q-ss Montezuma Fm

111: QT-ss sedimentary rocks

112: QT-ss Merced Fm

113: QT-ss Merced Fm

114: QT-ss Merced Fm

115: Tu-ss Wilson Grove Fm

116: Tu-ss Ohlson Ranch Fm of Higgins (1960) undiv.

117: Tu-ss sandstone member of Ohlson ranch Fm of Higgins (1960)

118: Tu-ss Garrity unit of Wagner (1978)

120: QT-sm sedimentary rocks

121: QT-sm sedimentary rocks

122: QT-ss sedimentary rocks

123: Tu-sm Glenn Ellen and Huichica Fms and older fluvial deposits

124: Tu-ss Tehama Fm

125: Tu-sm Tehama Fm

126: Tu-sm Oro Loma Fm of Briggs (1953)

127: Tu-sm Purisima Fm and siltstone and sandstone equiv. to Purisima Fm (Allen 1946)

128: Tu-ss upper Mulholland Fm of Ham (1952)

129: Tu-sm lower Mulholland Fm of Ham (1952)

130: Tu-sm Contra Costa Group undiv.

131: Tu-sm Contra Costa Group undiv.

132: Tu-sm clastic member of Moraga Fm

133: Tu-sm Orinda Fm

134: Tu-sm Orinda Fm

140: QT-tf tuffaceous member of Glen Ellen Fm

141: Tu-sm sedimentary deposits

150: p-md Montezuma Fm

151: QT-md sedimentary rocks

152: QT-md sedimentary rocks

153: QT-md clayey facies of Glen Ellen and Huichica Fms

154: Tu-md Siesta Fm

155: Tu-md Petaluma Fm

156: Tu-md claystone member of Petaluma Fm

200: Tu-bv andesite and basalt

201: Tu-bv andesite

202: Tu-fv andesitic to dacitic Sonoma Volcanics

203: Tu-fv rhyodacite intrusions

204: Tu-fv rhyolitic Sonoma Volcanics

210: Tu-bv Putnam Peak Basalt

211: QT-bv basalt

212: Tu-bv olivine basalt member of Clear lake Volcanics

213: Tu-bv Bald Peak Basalt

214: Tu-bv basalt flows of Sonoma Volcanics

215: Mx-fv Leona Rhyolite

216: Mz-fv rhyolite including Alum Rock Rhyolite of Crittenden (1951)

217: QT-fv Clear lake Volcanics

19
218: Tu-fv rhyolitic flows of Sonoma Volcanics

219: Tu-fv perlitic rhyolite of Sonoma Volcanics

220: Tu-fv soda rhyolite flows of Sonoma Volcanics

221: Mz-fv Northbrae Rhyolite

230: Tu-bv basalt

231: Tu-bv Page Mill Basalt

232: Mz,Tu-bv Page Mill Basalt Mindego Basalt diabase and other volcanic rocks

233: Tu-bv basalt and andesite member of Moraga Fm

234: Tu-bv andesitic to basaltic flows of Sonoma Volcanics

235: Tu-fv andesitic and basaltic flows of Sonoma Volcanics

236: Tu-fv Sonoma Volcanics

237: Tu-fv andesitic to basaltic flows of Sonoma Volcanics and sedimentary rocks

238: Tu-tf ash-flow tuff of Sonoma Volcanics and andesitic to basaltic flows

239: Mz-fv volcanic rocks at Lone Hill

240: Tu-fv rhyolite flows of Sonoma Volcanics

241: Tu-ab rhyolitic breccia of Sonoma Volcanics

250: Mz-bv volcanic rocks

251: Mz-bv Spilite near Black Point

253: Mz-mv greenstone of Franciscan assemblage and quartz keratophyre

254: Mz-mv metagreenstone of Franciscan assemblage

255: Mz-mv basaltic pillow lava and breccia

256: Mz-bv basaltic pillow lava and breccia

260: Tu-fv volcanic rocks

261: Tu-wt welded tuff of Sonoma Volcanics

262: Tu-wt xenolithic welded tuff of Sonoma Volcanics

270: Tu-tf ash-flow tuff of Sonoma Volcanics

271: Tu-tf tuff member of Clear Lake Volcanics

272: Tu-tf lithic tuff of Sonoma Volcanics

273: Tu-ab agglomerate of Sonoma Volcanics

274: Tu-bv andesitic or basaltic agglomerate

275: Q-ab tuff and rhyolitic gravel

280: QT-tf Cache Fm

281: Tu-fv Lawlor Tuff

282: Tu-fv Pinole Tuff

283: Tu-fv tuff at base of Contra Costa Group

284: Tu-fv tuff member of Orinda Fm

285: Tl-fv tuff member of Kirker Fm of Primmer (1964)

290: Tl-fv Sonoma Volcanics

291: Tu-fv volcanic rocks equiv. to Quien Sabe Volcanics of Leith (1949)

300: Mz-bv fluvial and lacustrine deposits of Little Sulphur Creek

301: Tu-ss conglomerate in G member of Wagner (1978) of Briones Sandstone

302: Tu-ss basal conglomerate of Monterey Group

303: Tl-ss conglomerate at Point Reyes

310: Tu-ss San Gregorio Sandstone Member of Purisima Fm and Santa Margarita Sandstone

311: Tu-ss sandstone

312: Tu-ss sandstone

313: Tu-ss Laird Sandstone

314: Tl-ss middle sandstone unit of Nortonville Shale

315: Tl-ss upper sandstone member of unnamed formation

20
320: Tu-ss Cierbo Sandstone

321: Tu-ss Temblor(?) Sandstone

322: Tu-ss Temblor(?) Sandstone

323: Tu,Tl-ss Lompico Sandstone Butano Sandstone Zayante Sandstone and sandstone of Mt 

Madonna area

330: Tu-ss E member of Wagner (1978) of Briones Sandstone

331: Tu-ss D member of Wagner (1978) of Briones Sandstone

332: Tu-ss sandstone unit of Monterey Group

333: Tu-ss Oursan Sandstone

334: Tu-ss Sobrante Sandstone

335: Tl-ss tuffaceous sandstone member of Kirker Fm of Primmer (1964)

340: Tu-ss glauconitic sandstone unit

342: Tu-ss Temblor(?) Sandstone

343: Tl-ss upper sandstone member of Domengine Sandstone

344: Tl-ss upper part of Domengine Sandstone

345: Tl-ss divisions A and B of Clark and Woodford (1927) of Meganos Fm

350: Tu-sm San Pablo Group undiv.

351: Tu-ss San Pablo Group undiv.

352: Tu-ss Neroly Sandstone

353: Tu-ss Cierbo Sandstone

354: Tu-sm Cierbo Sandstone

355: Tu-ss Briones Sandstone

356: Tu-ss Briones Sandstone undiv. and upper part of Briones Sandstone

357: Tu-ss Briones Sandstone

358: Tu-sm Briones(?) Sandstone

359: Tu-ss Briones Sandstone

360: Tu-ss E member of Wagner (1978) of Briones Sandstone

361: Tu-ss lower part of Briones Sandstone

362: Tu-ss lower part of Briones Sandstone

363: Tu-ss unnamed sandstone and Purisima Fm

364: Tu-ss Hambre Sandstone of Monterey Group

365: Tu-sm sandstone and mudstone near Fort Ross

366: Tu-ss Temblor Sandstone

367: Tu-ss San Ramon Sandstone

368: Tu-ss Sobrante Sandstone of Monterey Group and San Ramon Sandstone

369: Tl-ss Vaqueros Sandstone Butano Sandstone and Locatelli Fm

370: Tl-sm Butano Sandstone

371: Tl-ss Markley(?) Fm

372: Tl-ss Markley Fm

373: Tl-sm lower sandstone member of Markley Fm and Markley Fm

374: Tl-sm shale and sandstone

375: Tl-ss Tolman Fm of Hall (1958)

376: Tl-ss Domengine Sandstone

377: Tl-ss division D of Clark and Woodford (1927) of Meganos Fm

378: Tl-ss strata of German Rancho

379: Tl-ss undiv. sandstone mudstone and conglomerate

380: Tu-ss Purisima Fm undiv. Tunitas Sandstone and Tahana Members of Purisima Fm and 

unnamed sandstone

381: Tu-ss Neroly Sandstone

21
382: Tu-sm G and I members of Wagner (1978) of Briones Sandstone

383: Tu-sm F member of Wagner (1978) of Briones Sandstone

384: Tu-sm sandstone siltstone and shale mapped as Monterey Shale by Weaver (1949)

385: Tu-ss sandstone unit of Monterey Group

386: Tu-ss Hambre Sandstone of Monterey Group

387: Tu-ss Hambre Sandstone of Monterey Group

388: Tu-ss Oursan Sandstone of Monterey Group

389: Tu-ss Oursan Sandstone of Monterey Group

390: Tu-ss sandstone member of Claremont Shale of Monterey Group

391: Tu-sm Sobrante Sandstone of Monterey Group

392: Tu-ss Sobrante Sandstone

393: Tu-ss Temblor(?) Sandstone

394: Tl-ss San Ramon Sandstone and sandstone member of Kirker Fm of Primmer (1964)

399: Tu-sm sandstone

400: Tu-sm Neroly Sandstone

401: Tu-sm Neroly Sandstone

402: Tu-sm Neroly Sandstone

403: Tu-ss Neroly Sandstone

404: Tu-sm Briones Sandstone

405: Tu-sm upper part of Briones Sandstone

406: Tu-sm sandstone unit of Monterey Group

407: Tu-sm unnamed unit

408: Tu-sm Sobrante(?) Sandstone of Monterey Group

409: Tu-sm San Ramon Sandstone

410: Tl-ss Markley Fm

411: Tl-sm Markley(?) Fm

412: Tl-sm upper sandstone member of Markley Fm

413: Tl-sm sandstone member of Nortonville Shale

414: Tl-sm Domengine Sandstone

415: Tl-ss Domengine Sandstone

416: Tl-sm Domengine Sandstone

417: Tl-sm Domengine Sandstone

418: Tl-sm divisions D and E of Clark and Woodford (1927) of Meganos Fm

419: Tl-ss sandstone unit in division C of Clark and Woodford (1927) of Meganos Fm

420: Tl-sm divisions A B and C of Clark and Woodford (1927) of Meganos Fm

421: Tl-sm Butano(?) Sandstone

422: Tl-sm Tesla Fm

423: Tl-sm sandstone

424: Tl-sm Martinez Fm

425: Tl-ss lower glauconitic sandstone member of Martinez Fm

426: Tl-sm lower glauconitic sandstone member of Martinez Fm

430: Tu-sm siltstone and mudstone unit

431: Tu-ss siltstone member of Neroly Sandstone

432: Tu-sm lower part of Briones Sandstone

433: Tu-md clay shale unit of Monterey Group

435: Tl-md Markley Fm

436: Tl-md Sidney siltstone unit probably equiv. to Sidney Flat Shale Member of Fulmer 

(1964) of Markley Fm

438: Tl-md Nortonville Shale

22
439: Tl-sm Nortonville Shale

440: Tu-sm Nortonville Shale

441: Tl-sm lower part of Domengine Sandstone equiv. to Muir Sandstone of Weaver (1953)

442: Tl-md lower siltstone and claystone member of Domengine Sandstone

443: Tl-sm lower siltstone and claystone member and white sandstone unit of Domengine 

Sandstone

444: Tl-md division E of Clark and Woodford (1927) of Meganos Fm

445: Tl-md division C of Clark and Woodford (1927) of Meganos Fm

446: Tl-sm sandstone unit in division C of Clark and Woodford (1927) of Meganos Fm

448: Tl-md unnamed formation

449: Tl-md Martinez Fm undiv.

450: Tl-md Martinez Fm

451: Tl-md upper siltstone and shale member of Martinez Fm

452: Tl-ss lower glauconitic sandstone member of Martinez Fm

453: Tl-md unnamed sedimentary unit

460: Tu,Tl-md Lobitos Mudstone Mbr of Purisima Fm Lambert Sh San Lorenzo Fm Rices Mudstone Mbr of San Lorenzo Fm and mdst of Mayamus Flat

461: Tl-md Twobar Sh Member of San Lorenzo Fm shale member of Butano Sandstone Locatelli Fm and unnamed shale

465: Tl-md Nortonville Shale

466: Tl-md upper shale unit of Nortonville Shale

467: Tl-md lower shale unit of Nortonville Shale

468: Tl-md division C of Clark and Woodford (1927) of Meganos Formation

469: Tl-md division C of Clark and Woodford (1927) of Meganos Fm

470: Tl-md Vacaville Shale of Merriam and Turner (1937)

471: Tl-md Capay Fm

472: Tl-md Capay Fm

473: Tl-md unnamed sedimentary unit

474: Tl-md upper siltstone and shale member of Martinez Fm

500: Tu-sl Pomponio Mudstone Member of Purisima Fm Monterey Group Santa Cruz Mudstone Lambert Shale and shale of Mt Pajaro area

501: Tu-sl Monterey Group

503: Tu-sl shale unit of Monterey Group

504: Tu-sl shale unit of Monterey Group

506: Tu-sl Claremont Shale of Monterey Group

507: Tu-sl Claremont Shale of Monterey Group

508: Tu-sl Claremont Shale of Monterey Group

509: Tu-sl shale and sandstone

510: Tu-sl Pinehurst Shale

511: Mz-sl chert and metachert of Franciscan assemblage

519: Tu-dm diatomite with interbedded sand gravel and tuff

520: Tu-ls limestone in E member of Wagner (1978) of Briones Sandstone

521: Tu-md Hercules Shale Member of Briones Sandstone

522: Tu-sl Monterey Group

523: Tu-sl Monterey Group

524: Tu-sl Monterey Group

525: Tu-sl Monterey Group

526: Tu-sl Monterey Group

23
527: Tu-sm Monterey Group undiv.

528: Tu-sm Monterey Group undiv.

529: Tu-sl Rodeo Shale of Monterey Group

530: Tu-sl Tice Shale of Monterey Group

532: Tu-sl Tice Shale of Monterey Group

533: Tu-ss Oursan Sandstone Claremont Shale and Sobrante Sandstone undiv. of Monterey 

Group

534: Tu-sl Claremont Shale of Monterey Group

535: Tu-dm diatomite unit of Monterey Group

536: Tu-sl Lambert Shale

537: Tl-md upper part of Sidney Flat Shale Member of Fulmer (1964) of Markley Fm

538: Tl-md lower part of Sidney Flat Shale Member of Fulmer (1964) of Markley Fm

539: Tl-md Markley Fm equiv. to Kellogg Shale of Clark and Campbell (1942)

540: Tl-md Markley Fm and Nortonville Shale undiv.

541: Tl-sl mudstone

600: Mz-ss conglomerate unit of Great Valley sequence

601: Mz-ss conglomerate unit of Great Valley sequence

602: Mz-ss conglomerate unit of Great Valley sequence

603: Mz-ss Novato Conglomerate

604: Mz-ss conglomerate unit of Great Valley sequence

610: Mz-ss conglomerate in unnamed unit

611: Mz-ss conglomerate unit of Great Valley sequence

612: Mz-ss conglomerate unit of Great Valley sequence that is part of Del Valle Fm of Hall 

(1958)

613: Tl-sm strata of Stewarts Point

614: Mz-ss conglomerate member of Redwood Canyon Fm

615: Mz-ss Oakland Conglomerate

616: Mz-ss conglomerate

620: Mz-ss mapped sandstone in unnamed unit

621: Mz-ss sandstone unit in unnamed sandstone and shale of Great Valley sequence

622: Mz-sm sandstone unit of Great Valley sequence

623: Mz-sm sandstone unit of Great Valley sequence

624: Mz-sm sandstone and shale unit of Great Valley sequence

625: Mz-ss sandstone unit of Great Valley sequence

626: Mz-ss sandstone unit of Great Valley sequence

627: Mz-ss sandstone unit of Great Valley sequence

628: Mz-ss Deer Valley Fm of Colburn (1964)

629: Mz-sm mappable sandstone in lower member of Moreno Fm

630: Mz-ss Redwood Canyon Fm

631: Mz-ss sandstone unit of Great Valley sequence equiv. F-2 zone of Goudkoff (1942)

632: Mz-ss Guinda Fm of Kirby (1942)

633: Mz-ss Sites Fm of Kirby (1942)

634: Mz-ss Venado Fm of Kirby (1943)

635: Mz-sm lower part of Knoxville Fm (Robinson 1965) and part of shale unit

640: Tl-sm unnamed sandstone shale and conglomerate

641: Mz-sm shale and sandstone in unnamed unit

642: Tl-sm shale and sandstone

643: Mz-sm unnamed unit of Great Valley sequence

644: Mz-sm sandstone and shale unit of Great Valley sequence

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645: Mz-sm sandstone and shale unit of Great Valley sequence

646: Mz-sm sandstone shale and minor conglomerate unit of Great Valley sequence

647: Mz-sm sandstone and shale unit of Great Valley sequence and sandstone of Nibbs Knob 

area

648: Mz-sm unnamed formation of Great Valley sequence

649: Mz-sm sandstone unit of Great Valley sequence

650: Mz-sm Joaquin Ridge Sandstone Member of Goudkoff (1945) of Panoche Fm

651: Mz-sm Mappable sandstone interbeds in upper shale and siltstone member of Marlife 

Shale of Payne (1962)

652: Mz-sm middle sandstone member of Marlife Shale of Payne (1962)

653: Mz-ss sandstone unit of great Valley sequence equiv. G-1 zone of Goudkoff (1942)

654: Mz-sm Joaquin Miller Fm

655: Mz-sm unnamed sandstone and shale of Great Valley sequence

656: Mz-sm,ss Pigeon Point Fm and sandstone at San Bruno Mtn

657: Mz-sm unnamed formation of Great Valley sequence

658: Mz-sm Great Valley sequence undiv.

659: Mz-sm sandstone and claystone unit of Great Valley sequence

660: Mz-md,sm shale unit of Great Valley sequence

661: Mz-md shale unit of Great Valley sequence

662: Mz-md shale unit of Great Valley sequence

663: Mz-md shale unit of Great Valley sequence

664: Mz-sm sandstone shale and minor conglomerate unit of Great Valley sequence

665: Mz-md sandstone unit of Great Valley sequence

666: Mz-sm strata of Anchor Bay

667: Mz-sm Shephard Creek Fm

668: Mz-md shale units of Great Valley sequence probably equiv. to E and F-2 zones of Goudkoff (1942)

669: Mz-md Forbes Fm of Kirby (1942)

670: Mz-md Funks Fm of Kirby (1942)

671: Mz-md Yolo Fm of Kirby (1942)

672: Mz-md upper siltstone member of Moreno Fm

673: Mz-md lower shale and claystone member of Moreno Fm

674: Mz-md shale interbeds in Joaquin Ridge Sandstone Member of Goudkoff (1945) of Panoche Fm

675: Mz-md upper shale and siltstone member of Marlife Shale of Payne (1962)

676: Mz-sm lower shale and siltstone member of Marlife Shale of Payne (1962)

677: Mz-md mappable sandstone interbeds in lower shale and siltstone member of Marlife 

Shale of Payne

678: Mz-sm unnamed sandstone and shale of Great Valley sequence

679: Mz-md shale unit in unnamed sandstone and shale of Great Valley sequence

680: Mz-sm unnamed shale of Great Valley sequence

681: Mz-md unnamed shale of Great Valley sequence

682: Mz-md unnamed unit of Great Valley sequence

683: Mz-sm unnamed formations and undiv. rocks of Great Valley sequence

684: Mz-md siltstone and minor sandstone unit of Great Valley sequence

685: Mz-md upper part of Knoxville Fm (Robinson 1956) and part of shale unit

686: Mz-md Knoxville Fm

687: Mz-md mudstone and siltstone unit

688: Mz-sm shale unit

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689: Mz-md shale unit including Knoxville Fm of Crittenden (1951)

700: Mz-ms unsheared sandstone and shale of Franciscan assemblage

701: Mz-ms sandstone and shale of Franciscan assemblage

702: Mz-ms flysch-like shale and sandstone of Franciscan assemblage

703: Mz-ms chiefly metagraywacke of Franciscan assemblage

704: Mz-ms Franciscan assemblage undiv.

800: Mz-mm severely sheared rocks of Franciscan assemblage

801: Mz-mm melange of largely clastic rocks of Franciscan assemblage

802: Mz-mm melange of metamorphic rocks of Franciscan assemblage

803: Mz-mm variably sheared sandstone and shale of Franciscan assemblage

804: Mz-mv variably sheared metagreenstone of Franciscan assemblage

805: Mz-sp sheared serpentinite

900: Mz-sp largely unsheared ultramafic rock and serpentinite

901: Mz-sp ultramafic rock

902: Mz-bv diabase and gabbro

903: Mz-bv diabase

904: Mz-bv diabase

905: Mz-bv diabase

906: Mz-gr granitic rocks

907: Mz-gr granitic rocks and minor gabbro

908: Mz-sch marble quartzite and schist

909: Mz-ls limestone of Franciscan assemblage including Calera Limestone of Lawson 

(1902)

910: Tu-sc silica-carbonate rock

911: Mz-hg high-grade metamorphic rocks of Franciscan assembla

26