CGS Preliminary Geologic Maps

The California Geological Survey has compiled several updated and new geologic maps that are considered Preliminary, awaiting official publication. We make digital versions of these Preliminary maps available before publication so you may have timely access to the information.

Below: Index map showing availability of Preliminary and Published maps of the current Regional Geologic Map series. Click or tap the image to see a larger version.
Map of California showing available quadrangles as summarized in the figure caption.

You can download our Preliminary Regional Geologic Maps using the links provided below. Please note, our Preliminary maps are available as PDF files only. Printed versions are not available.

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

Alturas, 2016
Cedarville, 2017
Crescent City-Orick, 2012
Eagle Lake, 2014
Lodi, 2009
Long Beach, 2016
Los Angeles, 2016
Napa-Bodega Bay, 2017
Pt. Sur, 2016
Sacramento, 2011
Santa Barbara (east half), 2008
Susanville, 2013

Preliminary 7.5 Minute Quadrangles (1:24,000 scale)

Click a region in the list below to jump to a list of that region's 7.5 minute quadrangles.


Northern San Francisco Bay Region

Map of the Northern San Francisco Bay Region showing available quadrangles.
Note: The 7.5 minute quadrangles within the Napa 30-by-60 minute quadrangle (shown above in red) have been updated and are superseded by the Preliminary Geologic Map of the Napa-Bodega Bay 30-by-60 minute quadrangle (Wagner and Gutierrez, 2017).

Central Sierra Foothills Region

Map of the Central Sierra Foothills Region showing available quadrangles.

San Luis Obispo Region

Map of the San Luis Obispo Region showing available quadrangles.

Lancaster-Victorville Region

Map of the Lancaster-Victorville Region showing available quadrangles.

Santa Barbara-Los Angeles Region

Map of the Santa Barbara-Los Angeles Region showing available quadrangles.
Note: The 7.5 minute quadrangles within the Los Angeles 30-by-60 minute quadrangle (shown above in red) have been updated and are superseded by the Preliminary Geologic Map of the Los Angeles 30-by-60 minute quadrangle (Campbell, et al, 2014).

Oceanside-San Diego Region

Map of the Oceanside-San Diego Region showing available quadrangles.
Note: The 7.5 minute quadrangles within the Oceanside 30-by-60 minute quadrangle (shown above in red) have been updated and are superseded by the Geologic Map of the Oceanside 30-by-60 minute quadrangle (Kennedy and Tan, 2007).

About CGS Preliminary Regional Geologic Maps

The California Geological Survey prepares geologic maps in cooperation with the U.S. Geological Survey’s National Cooperative Geologic Mapping Program. We prepare Preliminary maps as 7.5 minute quadrangles at 1:24,000 scale, which we then compile into 30-by-60 minute quadrangles at 1:100,000 scale. The 30-by-60 minute quadrangles include all of the detail of the 7.5 minute quadrangles. When an entire 30-by-60 minute quadrangle is compiled, reviewed, and approved, we release it into our official Published Regional Geologic Map series.

Geologic mapping priorities are established by the California State Geologist and the California Geologic Mapping Advisory Committee.

Technical comments can be emailed to Marc Delattre