Preliminary Regional Geologic Maps

Below: Index map showing available quadrangles of the current California 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.

The California Geological Survey prepares geologic maps in cooperation with the U.S. Geological Survey’s National Cooperative Geologic Mapping Program. Geologic mapping priorities are established by the California State Geologist and the California Geologic Mapping Advisory Committee.

We begin with 7.5 minute quadrangles at 1:24,000 scale. We compile those into 30-by-60 minute quadrangles at 1:100,000 scale, which retain 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 California Regional Geologic Map series.

The maps on this page are considered preliminary. We make digital versions of preliminary maps available so you may have timely access to the information. You can download them using the links provided below. Please note, preliminary maps are available as PDF files only. Printed versions are not available.

For data requests and technical comments related to Geologic Mapping, please contact Janis Hernandez.

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


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

Select a region from the choices below to jump to a list of that region's 7.5 minute quadrangles.

Ukiah Region

Map of the North Coast Region showing available quadrangles.

Healdsburg-Napa Region

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The 7.5 minute quadrangles within the Napa 30-by-60 minute quadrangle (outlined in red below) have been updated and are superseded by the Preliminary Geologic Map of the Napa-Bodega Bay 30-by-60 minute quadrangle (Wagner and Gutierrez, 2017).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

San Andreas Region

Map of the Central Sierra Foothills Region showing available quadrangles.

Lancaster-Victorville Region

Map of the Lancaster-Victorville Region showing available quadrangles.

San Luis Obispo Region

Note: The 7.5 minute quadrangles shown below have been updated and are superseded by the Preliminary Geologic Map of the West Half of the San Luis Obispo 30-by-60 minute quadrangle (Wiegers, 2018; un-simplified digital database available upon request).
Map of the San Luis Obispo Region showing available quadrangles.

Santa Barbara-Los Angeles Region

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minute quadrangles within the Los Angeles 30-by-60 minute quadrangle (outlined in red below) have been updated and are superseded by the Preliminary Geologic Map of the Los Angeles 30-by-60 minute quadrangle (Campbell, et al, 2014).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

Oceanside-San Diego Region

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

New York Mountains (Ivanpah Region)

Map of the Ivanpah Region showing available quadrangles.

About the New York Mountains mapping project

New York Mountains project location and available quadrangles.

In 2019, the California Geological Survey entered into a cooperative agreement with the United States Geological Survey (USGS) to conduct geologic mapping of the New York Mountains at 1:24,000 scale. This project is supported in part by funding from the USGS Earth Mapping Resource Initiative (Earth MRI), and occurs within the Mountain Pass Rare Earth Element Focus Area.

The field area was selected due to its proximity to the world class, carbonatite-hosted, light rare earth deposit at Mountain Pass. Rare earth elements are among 50 minerals listed as critical by the USGS. Critical minerals are defined as being essential for manufacturing products significantly important to the economy and national security and as having supply chains vulnerable to outside disruption. The Earth MRI Project aims to gather information to identify potential domestic sources of critical minerals.


Web page by:
California Regional Geologic and Landslide Mapping Program

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