README FOR Open-File Report 97-744 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 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 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 over the Internet, or can be obtained by requesting a CD-R. 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. 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 (5.25 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 import.aml (of97-744_3c.tar) are packaged together in a single gzip-compressed tar file. The 8.8 MB gz file unzips to 40.7 MB tar file. of97-744-shapefiles.tar.gz: The tar file of ARCVIEW shape files (of97-744_3d.tar) and units database (of97-744_3e.dbf) are packaged together in a single gzip-compressed tar file. The 13.9 MB gz file unzips to 45.6 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: http/pubs.usgs.gov/of/1997/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 obtain files from the database on CD-R send a request 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