DESCRIPTION OF DIGITAL FILES FOR PRELIMINARY GEOLOGIC MAP OF THE Hemet 7.5' QUADRANGLE, RIVERSIDE COUNTY, CALIFORNIA, VERSION 1.1 By Kelly Bovard INTRODUCTION Open-File Report 2004-1455 is a digital geologic data set that maps and describes the geology of the Hemet 7.5' quadrangle, southern California. The Hemet quadrangle database is one of several 7.5' quadrangle databases that are being produced by the Southern California Areal Mapping Project (SCAMP). These maps and databases are, in turn, part of the nation-wide digital geologic map coverage being developed by the National Cooperative Geologic Map Program of the U.S. Geological Survey (USGS). This document describes the types and contents of files comprising the database. Information on how to extract and plot the map also is provided. This publication includes ARC/INFO (Environmental Systems Research Institute, http://www.esri.com) version 8.2 coverages and associated tables; Encapsulated Postscript (.eps) files of the geologic map, correlation of map units, and description of map units; Portable Document Format (PDF) files of the geologic map, correlation of map units, and description of map units; and a text file of FGDC-compliant metadata for the report. GEOLOGIC MAP DATABASE FILES AND ASSOCIATED FILES All files listed in this section are in a compressed file named hmt.zip; see section below titled, SOFTWARE UTILITIES. Raster file Resultant image Contains hmt.tif Hemet base map Topographic base from 500 dpi scan of USGS Hemet 7.5' quadrangle, 1973 ARC/INFO Coverage Contains Interchange file hmt1_geo.e00 hmt1_geo Contacts, faults and geologic units hmt1_str.e00 hmt1_str Attitudes and dip values hmt1_ano.e00 hmt1_ano Annotation subclass: geo (unit labels) fault (fault names) Leaders The directory, info/, is produced in the process of importing interchange files to ARC coverages in ARC/INFO. The info/ directory contains: Polygon attribute table hmt1_geo.pat Arc attribute tables hmt1_geo.aat, hmt1_ano.aat Point attribute tables hmt1_str.pat Annotation attribute tables hmt1_ano.tatgeo, hmt1_ano.tatfault FILES FOR VIEWING AND PLOTTING hmt1_map.zip A zipped Encapsulated Postscript file for viewing and plotting the geologic map at full scale, correlation of map units and description of map units. The plot is approximately 44 x 36 inches in size hmt1_map.pdf A Portable Document Format (PDF) file for viewing and plotting the geologic map at full scale, correlation of map units and description of map units. The plot is approximately 44 x 36 inches in size. For those having access to large-format plotters such as HP650C, HP755C, HP2500c, and HP5000, plots may be made directly from the included plot file. METADATA hmt1_met.txt Federal Geographic Data Committee (FGDC) compliant metadata file derived from the digital database. GEOLOGIC SYMBOLS Files in the plot package have been prepared to produce optimum plots using the shade, line, and marker sets listed below; these symbol sets and supporting fonts are included in a zipped file named symbols.zip (0.18 Mb). geoscamp2.lin Lineset for lines geoscamp2.mrk Markerset for points wpgcmykg.shd Shadeset for colors geology2.shd Shadeset for patterns fnt026 Font required for geoscamp2.lin fnt037 Font required for geoscamp2.mrk fnt035 Font required for geology2.shd geoage folder contains files for Geoage font group Special geologic characters used in the unit designations are from the Geoage font group and are contained in the geoage folder within the symbols.zip file. The Geoage fonts are used in conjunction with the geofont.txt textset when using ESRI software. The geoage folder contains fonts, the geofont.txt textset, and explanatory files. SOFTWARE UTILITIES Files that have the .zip file extension were compressed using WinZip, available at http://www.winzip.com. HOW TO OBTAIN THE DIGITAL FILES The digital files constituting the geologic map database of this report may be obtained via the Internet from the U.S. Geological Survey publications website. Go to the web page at http://pubs.usgs.gov/of/2004/1455 and follow the directions to download the files. EXTRACTING THE GEOLOGIC MAP DATABASE FROM THE ZIP FILE After downloading the files, they must be uncompressed using a gzip utility such as gzip itself or WinZip. This process will create a directory, hmt/, that contains the ARC/INFO interchange files and supporting files. CONVERTING THE ARC/INFO EXPORT FILES ARC interchange (.e00) files are converted to ARC coverages using the ARC command IMPORT with the option COVER. ARC interchange files also can be read by some other Geographic Information Systems. Please consult your GIS documentation to see if you can use ARC interchange files and to determine the procedure for importing them. PORTABLE DOCUMENT FORMAT (PDF) FILES The PDF files are accessed using Adobe Acrobat Reader software, available free from the Adobe website http://www.adobe.com. Follow instructions at the website to download and install the software. Acrobat Reader contains an on-line manual and tutorial. DIGITAL GEOLOGIC MAP SPECIFICATIONS Base map The base map image (hmt.tif) was prepared by scanning a scale-stable clear film of the U.S. Geological Survey, 1:24,000 Hemet 7.5â quadrangle (1973) topographic map. Scanning was done using an Anatech Eagle 4080 monochrome 800 dpi scanner; at a resolution of 500 dpi. The raster scan was converted to a monochromatic image in ARC/INFO, and registered and rectified to the Hemet 7.5â quadrangle. No elements of the base layer are attributed. The base map is provided for reference only. Spatial resolution Use of this digital geologic map database 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 1:24,000 means that higher resolution information is not generally present in the dataset. Plotting at scales larger than 1:24,000 will not yield greater real detail, although it may reveal fine-scale irregularities above the intended resolution of the database. Similarly, although higher resolution data is incorporated at a few places, the resolution of the combined output will be limited by the lower resolution data. Map accuracy standards Until uniform National geologic map standards are developed and adopted, lines and points on SCAMP 1:24,000 scale geologic maps that are located to within 15 meters, relative to accurately located features on the base map, are considered to meet map accuracy standards. Dashed lines, indicated in the database as approximately located or inferred, are generally located within 30 meters, relative to accurately located features on the base map. Faults and landslides This database is sufficiently detailed to identify and characterize many actual and potential geologic hazards represented by faults and landslides, but is not sufficiently detailed for site-specific determinations. Faults shown do not take the place of fault rupture hazard zones designated by the California State Geologist (see Hart, 1988). REFERENCES Hart, E.W., 1988, Fault-rupture 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