California Regional Geologic Maps

Above: Index map showing available quadrangles of the modern California Regional Geologic Map series. Smallest squares represent 7.5 minute quadrangles (1:24,000 scale). Larger rectangles represent 30-by-60 minute quadrangles (1:100,000 scale). Click or tap the image to open a larger version.

For decades the Geologic Atlas of California (discussed in the next section) has been the primary source of regional-scale geologic maps in California. In an effort to keep the maps current, the CGS has been compiling a new series of Regional Geologic Maps (RGM), starting in 1981. The new maps cover the same areas as the older Geologic Atlas of California, but show more detail and use geologic formations rather than the simplified geologic time-based units.

The CGS published the first six maps of this series at 1:250,000 scale. After 1992, we began producing more detailed, larger scale maps (1:100,000 and 1:24,000 scales). To date, there are more than 100 new or updated geologic maps in the current RGM series.

You can download maps of the Regional Geologic Map series using the links provided below. Printed versions can be purchased from the CGS Publications sales desk.

7.5 Minute Quadrangles (1:24,000 scale)

7.5 minute quadrangles (1:24,000 scale) are available on our Preliminary Regional Geologic Maps page.

30-by-60 Minute Quadrangles (1:100,000 scale)

San Diego, 2008 (RGM 3)

Stockton, 2023 (RGM 5) (NEW)

Other 30-by-60 Minute Quadrangles

Additional 30-by-60 minute quadrangles (1:100,000 scale) are available on our Preliminary Regional Geologic Maps page..

The Geologic Atlas of California (1:250,000 scale)

Map showing the 27 quadrangles of the Geologic Atlas of California.
Above: Index map showing the quadrangles of the Geologic Atlas of California.

The Geologic Atlas of California was published between 1958 and 1969. Although more recent and more detailed mapping is available in many areas (see newer Regional Geologic Map Series above), this set of maps is still the most detailed interpretation available for the entire state. It provides a complete, consistent view of the geology of the state, prepared at 1:250,000 scale. The Geologic Atlas uses a single set of rock units defined by geologic time, rather than geologic formations defined by time and lithology. This allows a simplified, uniform depiction of geologic units.

The following index map and list provide the areas covered by the individual sheets of the Geologic Atlas. You can download maps from the Geologic Atlas of California using the links provided in the list.

Alturas, 1958 (GAM 1)

Bakersfield, 1964 (GAM 2)

Chico, 1962 (GAM 3)

Death Valley, 1974 (GAM 4)

Fresno, 1965 (GAM 5)

Kingman, 1961 (GAM 6)

Long Beach, 1962 (GAM 7)

Los Angeles, 1969 (GAM 8)

Mariposa, 1967 (GAM 9)

Needles, 1963 (GAM 10)

Redding, 1962 (GAM 11)

Sacramento, 1965 (GAM 12)

Salton Sea, 1967 (GAM 13)

San Bernardino, 1967 (GAM 14)

San Diego-El Centro, 1962 (GAM 15)

San Francisco, 1961 (GAM 16)

San Jose, 1966 (GAM 17)

San Luis Obispo, 1958 (GAM 18)

Santa Ana, 1965 (GAM 19)

Santa Cruz (Monterey), 1958 (GAM 20)

Santa Maria, 1959 (GAM 21)

Santa Rosa, 1963 (GAM 22)

Trona, 1962 (GAM 23)

Ukiah, 1960 (GAM 24)

Walker Lake, 1963 (GAM 25)

Weed, 1963 (GAM 26)

Westwood, 1960 (Susanville) (GAM 27)

Statewide Geologic Map and Fault Activity Map of California (1:750,000 scale)

CGS prepared these editions of the Geologic Map of California and the Fault Activity Map of California in recognition of the California Geological Survey’s 150th Anniversary.

Click either image to learn more.

Web page by:
California Geological Survey - Regional Geologic and Landslide Mapping Program

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