Geologic Maps

Contents:
Description of the Maps
How to Find the Maps
Indexes to Geologic Maps
San Diego County Geologic Maps

See also: Map Collection | Map Basics

Description of the Maps

A geologic map uses a combination of colors, lines, and symbols to depict the distribution of geologic features. The colors on the map represent geologic units, or type of rock. Symbols (usually letters such as Qhb) give further information about these geologic units. Geologic maps identify such things as bedrock formations, surficial units (soils, landslides, etc.), and geologic structures (faults, folds, etc.).

For more information about geologic mapping, see Geologic Maps, a USGS guide to basic information about geologic maps, such as interpreting the colors, lines, and symbols. For more information about geology, see the library's Geology Subject Guide

How to find the Maps

Geologic maps are not produced for every area at every scale. For some areas, a small scale (less detailed) geologic map is all that is available.

Geologic maps can be found in books, government documents, and journals and are also published separately as flat sheets or folded into envelopes. They are located in various areas of the library, including the Map Collection, 5th floor books, and the government publications collections. Due to the variations in the way they are published, identifying maps can be problematic and finding them in the library can be time-consuming. If you need help with this type of material, please ask a librarian for assistance.

Indexes to Geologic Maps

Paper indexes to geologic maps owned by the SDSU library are available for most states. They are located on the Map Index Table in the Reference Services Division, near the map collection.

Geology of San Diego County: a Bibliography with Subject Index CDMG.
Ref TN 24.C2 A32 v.96

Index to Geologic Maps of California CDMG.
Ref TN 24.C2 A33 no.51-60 (1957 - 1960)
Ref TN 24.C2 A33 no.52B (1961 - 1964)
Ref TN 24.C2 A33 no.102 (1965 - 1968)
Ref TN 24.C2 A33 no.130 (1969 - 1975)

Geologic Map Index to United States Geological Survey 7.5' and 15' Quadrangles of California. Joe Crotts, CSU Chico
"This index covers the detailed geologic maps of California which are distributed among the fourteen irregular issued map and monograph series published by the United States Geological Survey. "

Index to Geologic Mapping in California CGS.
"This index contains lists of selected geologic mapping in California prepared by the Regional Geologic Mapping Project (RGMP). The RGMP staff monitors the literature and collects references that contain geologic mapping that may be useful for future compilations. Therefore, this index is not a comprehensive listing of geologic maps of California. In an effort to cover each 1:250,000 scale quadrangle with geologic mapping, selected graduate theses and unpublished maps have been included. In addition, Division of Mines and Geology (DMG) Open-File Reports that contain geologic mapping are indexed. "

GeoRef
The most comprehensive database of bibliographic information in the geosciences. Established by the American Geological Institute, it provides access to over 1.8 million references to articles, books, maps, conference papers, reports, and theses, covering the geology of North America from 1785 to the present and the geology of the rest of the world from 1933 to present.

National Geologic Map Database (NGMDB) USGS.
Provides information about active geologic mapping in the United States being conducted through the National Cooperative Geologic Mapping Program. This program is coordinated by the U.S. Geological Survey and implemented by a consortium of geologic mappers from the USGS (FEDMAP), State Geological Surveys (STATEMAP), and academia (EDMAP). Note: California state maps from the Division of Mines and Geology are not yet listed in the database.

Southern California Areal Mapping Project USGS.
This online source provides a map index to information about published geologic maps as well as links to some available digital data. Note: The San Diego area is not yet included in the database.

San Diego County Geologic Maps

These are the most heavily used geologic maps of the area. For other geologic maps of San Diego, please see the indexes listed above or ask a librarian for assistance.

Geology of the San Diego Metropolitan Area, California CDMG. 1975. 1:48,000
Covers Del Mar, La Jolla, Point Loma, La Mesa, Poway, and SW 1/4 Escondido 7.5' quadrangles.
Location: Ref/CA C810 B9 no.200; Gov Pubs/CA C810 B9 no.200; 5th Floor Books TN24.C2 A3 v.200

Geology and Mineral Resources of San Diego County, California CDMG. 1963.
Location: Ref TN 24 C2 A35 v.3

Geologic Map of California: San Diego - El Centro Sheet CDMG. 1962. 1:250,000
Location: Gov Pubs/CA C810 G4 S14

Geologic Map of California: San Diego - Santa Ana Sheet CDMG. 1965. 1:250,000
Location: Gov Pubs/CA C810 G4 S20

Geology of National City, Imperial Beach and Otay Mesa Quadrangles, Southern San Diego Metropolitan Area CDMG. 1977. 1:24,000
Location: Gov Pubs/CA C810 M32 no.29

Geologic Maps of the Northwestern Part of San Diego County, California CDMG. 1996. 1:24,000
Location: Gov Pubs/CA C810 O63 96-02

California Continental Margin Geologic Map Series - Sheets #1 & #2 CDMG. 1987.
Location: Gov Pubs/CA C810 C66 no.1 & no.2