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U.S. Geological Survey Open-File Report 95–91

Preliminary Geologic Map of the Topanga 7.5' Quadrangle, Southern California: A Digital Database

Compiled by R.F. Yerkes and R.H. Campbell



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. This digital map database is compiled from previously published sources combined with some new mapping and modifications in nomenclature. The geologic map database delineates map units that are identified by general age and lithology 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 Yerkes and Campbell (1994). More specific information about the units may be available in the original sources. The content and character of the database and methods of obtaining it are described herein. The geologic map database itself, consisting of three 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 'topnga.'

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For additional information:
Contact Information, Western Region Geology and Geophysics Science Center—Menlo Park
U.S. Geological Survey
345 Middlefield Road, MS-973
Menlo Park, CA 94025-3591

Suggested citation:

R.F. Yerkes, R.F., and Campbell, R.H., compilers, 1997, Preliminary geologic map of the Topanga 7.5' quadrangle, southern California; a digital database: U.S. Geological Survey Open-File Report 95–91, available at

This report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Last modified April 17, 2012
First posted June 12, 1997

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