CGS Regional Geologic Maps

Current Regional Geologic Map Series (1981-Present)

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.

Published and Preliminary Maps of the Current Regional Geologic Map Series

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: ten are officially Published, while the remainder are still considered Preliminary (see the Preliminary Regional Geologic Maps sidebar on this page).

Sidebar: Preliminary Regional Geologic Maps

The California Geological Survey has several new and updated 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. Follow this link to explore our collection of Preliminary Regional Geologic Maps.

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

Published 30-by-60 minute quadrangles (1:100,000 scale)

Lake Tahoe Basin, 2005 (RGM 4)
Includes:

  • Geologic map
  • Pamphlet
  • GIS Data

Monterey, 2002 (RGM 1)
Includes:

  • Geologic map
  • Correlation of map units
  • Pamphlet
  • GIS Data

Oceanside, 2007 (RGM 2)
Includes:

  • Geologic map
  • Correlation of map units
  • Pamphlet
  • GIS Data

San Diego, 2008 (RGM 3)
Includes:

  • Geologic map
  • Correlation of map units
  • Pamphlet
  • GIS Data
For additional 30-by-60 minute quadrangles (1:100,000 scale) and 7.5 minute quadrangles (1:24,000 scale), visit our Preliminary Geologic Maps page
Below: Index map showing availability of Published and Preliminary maps of the current Regional Geologic Map series at 1:100,000 and 1:24,000 scales. Click or tap the image to see a larger version.
Map of California showing available quadrangles as summarized in the figure caption.

Published 1-by-2 and 1-by-3 degree quadrangles (1:250,000 scale)

Chico, 1992 (RGM 7A)
Includes:

  • Geologic map
  • Map explanation (correlation of map units)
  • Index to geologic maps used in compilation
  • Locations of rock samples dated by radiometric methods
  • Table of radiometric ages of rocks
  • Map showing recency of faulting

Sacramento, 1981 (RGM 1A)
Includes:

  • Geologic map
  • Map explanation (correlation of map units)
  • Index to geologic maps used in compilation
  • Locations of rock samples dated by radiometric methods

San Bernardino, 1986 (RGM 3A)
Includes:

  • Geologic map
  • Map explanation (correlation of map units)
  • Index to geologic maps used in compilation
  • Locations of rock samples dated by radiometric methods
  • Map showing recency of faulting

San Francisco-San Jose, 1991 (RGM 5A)
Includes:

  • Geologic map
  • Map explanation (correlation of map units)
  • Index to geologic maps used in compilation
  • Locations of rock samples dated by radiometric methods
  • Map showing recency of faulting

Santa Rosa, 1982 (RGM 2A)
Includes:

  • Geologic map
  • Map explanation (correlation of map units)
  • Index to geologic maps used in compilation
  • Locations of rock samples dated by radiometric methods
  • Map showing recency of faulting

Weed, 1987 (RGM 4A)
Includes:

  • Geologic map
  • Map explanation (correlation of map units)
  • Index to geologic maps used in compilation
  • Locations of rock samples dated by radiometric methods

The Geologic Atlas of California (1958-1969)

The Geologic Atlas of California was published between 1958 and 1969. Although more recent and more detailed mapping is available in many areas (see Current 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 show 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.

Below: Index map showing areas covered by the individual sheets of the Geologic Atlas of California.
Map of California showing quadrangles of the Geologic Atlas of California.

Statewide Geologic Map and Fault Activity Map of California (2010)

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.