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Preliminary Geologic Maps

The CGS preliminary geologic map series is intended to provide timely access to digital geologic maps being prepared by CGS in cooperation with the U.S. Geological Survey’s National Cooperative Geologic Mapping Program. These maps are in preliminary format and are available as PDF images only. Maps are prepared based on original geologic mapping and compilation as 1:24,000 scale 7.5-minute quadrangles and 1:100,000 scale 30 x 60 minute quadrangles. Compilation of 30 x 60 minute quadrangles includes all of the detail of included 7.5 minute quadrangles and commonly updates mapping to produce a seamless geologic map of the region. When all aspects of the geologic mapping of a region are compiled and reviewed, the 30 x 60 minute quadrangles are published in CGS’s Regional Geologic Map series. The listing below shows preliminary 7.5 minute quadrangles and 30 x 60 minute quadrangles as well as the 30 x 60 minute quadrangles that have been published as Regional Geologic Maps.

Click on quadrangle name in the list below to view or download the quadrangle. To view, click on the name of the quadrangle to open in Adobe Acrobat. From Acrobat you can download the map by selecting "save as" under the file menu and save to desired location. To download without opening the map, right click on the quadrangle name, and select "save target as" to save the file to the location you wish.

Technical comments can be sent to Marc Delattre: 


30x60-minute Quadrangles Available to View or Download:

Preliminary Maps


Crescent City - Orick               Napa
Geologic Map (5.2 MB)   Geologic Map (13.3 MB) 
Pamphlet (1.2 MB)    Pamphlet (1 MB) 
Eagle Lake   Sacramento
Geologic Map (5 MB)   Geologic Map (37.5 MB) 
Pamphlet (1.5 MB)   Pamphlet (1 MB)
Lodi    Santa Barbara (East Half) 
Geologic Map (28.9 MB)    Geologic Map (32 MB) 
Pamphlet - (1 MB)    Pamphlet (1 MB) 
Long Beach    Susanville 
Sheet 1 - Geologic Map    Geologic Map (6.6 MB) 
Sheet 2 - Correlation and Description of Map Units    Pamphlet (5.3 MB) 
Los Angeles     
Geologic Map (13.9 MB)     
Pamphlet (2.7 MB)   

Published Maps
The following geologic maps have been published as part of the Regional Geologic Map (RGM) series. These maps and other RGM maps can be purchased through the CGS Publications.

Lake Tahoe Basin                                                               Oceanside                                  
Geologic Map   Geologic Map
Pamphlet   Correlation of Map Units
View Online Map   Pamphlet
    View Online Map
Monterey   San Diego
Geologic Map   Geologic Map
Correlation of Map Units   Correlation of Map Units
Pamphlet   Pamphlet
View Online Map   View Online Map

Preliminary 7.5-minute Quadrangles Available to View or Download


Northern California Region:

Calistoga (4.1 MB)                Healdsburg (8.2 MB)                  Petaluma River (1.6 MB)
Camp Meeker (7.2 MB) Jimtown (9.0 MB) Rutherford (11 MB)
Capell Valley (7.7 MB) Kenwood (2.4 MB) Sears Point (2.0 MB)
Cotati (4.2 MB) Mt. George (3.4 MB) Sebastopol (3.7 MB)
Cuttings Wharf (3.0 MB) Mt. Vaca (2.8 MB) Sonoma (3.7 MB)
Fairfield North (6.2 MB) Napa (3.8 MB) Two Rock (4.0 MB)
Geyserville (3.6 MB) Novato (2.3 MB) Valley Ford (4.6 MB)
Glen Ellen (5.4 MB) Petaluma (2.5 MB) Yountville (10 MB)

San Luis Obispo Region:

Arroyo Grande (3.7 MB)                                                      Oceano (3.1 MB) 
Atascadero (3.6 MB)   Pismo Beach (4.5 MB) 
Morro Bay South (6.1 MB)   San Luis Obispo (5.5 MB)
Nipomo (4 MB)     

Lancaster-Victorville Region:

Apple Valley North (3.1 MB)                                                 Lancaster West (3.8 MB)
Del Sur (4.6 MB)   Little Buttes (2.1 MB)
Fairmont Butte (3.9 MB)   Palmdale (4.2 MB) 
Grapevine (3.5 MB)    Ritter Ridge (8.6 MB)  
Lake Hughes (6 MB)    Sleepy Valley (4.3 MB) 
Lancaster East (3.5 MB)   Victorville (6.4 MB) 

Santa Barbara-Los Angeles Region:

Baldwin Park (9.2 MB)                                                            Santa Paula (3.6 MB) 
El Monte (11.2 MB)   Santa Paula Peak (11 MB) 
Matilija (6.1 MB)   Saticoy (4.6 MB) 
Ojai (10 MB)   Ventura (6 MB)
Oxnard (2.2 MB)   White Ledge Peak (3.1 MB) 
Pitas Point (2.1 MB)   Whittier (4.6 MB)
Point Mugu (5.2 MB)      

Oceanside-San Diego Region:

Aguanga (5.2 MB)                                                    Otay Mesa (1.2 MB)  
Bonsall (3.2 MB)    Pala (4 MB) 
Boucher Hill (8.9 MB)    Pechanga (4.2 MB) 
Dana Point (2.3 MB)    Ramona (4.0 MB) 
El Cajon (2.2 MB)    San Clemente (5.2 MB) 
Escondido (2.7 MB)    San Onofre Bluff (1.9 MB) 
Fallbrook (4.7 MB)    San Pasqual - (2.5 MB) 
Jamul Mountains (2.1 MB)   San Vicente Reservoir (1.7 MB) 
Las Pulgas Canyon (3.7 MB)    Temecula (4.8 MB) 
Margarita Peak (5 MB)    Vail Lake (6.2 MB) 
Morro Hill (3 MB)    Valley Center (3.3 MB)