CGS Regional Geologic Maps

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 RGM Series section below), 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 index map below shows the areas covered by the individual sheets of the Geologic Atlas.

Geologic Atlas of California 1:250,000 scale maps

Regional Geologic Map Series (1981-Present)

For decades the Geologic Atlas of California (see section above) has been the primary source of regional-scale geologic maps in California. In an effort to keep our maps current, CGS has been compiling a new series of Regional Geologic Maps (RGM), starting in 1981. The new series covers 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. Six regional geologic maps were published at 1:250,000 before CGS changed to completing and publishing 1:100,000 scale geologic maps. Publishing at 1:100,000 allows regional geologic maps to show nearly all of the detail from the original mapping. To date, CGS has published four regional geologic maps at 1:100,000 scale and is working on several others. See our Preliminary Geologic Maps page for maps in progress.

Published RGM Series Maps

The following geologic maps have been published as part of the current Regional Geologic Map (RGM) series. These maps and their related information can be downloaded using the links below. Printed versions can be purchased from CGS Publications.

RGM 1:100,000 Scale Maps

Lake Tahoe Basin, 2005
Includes:

  • Geologic map
  • Pamphlet
  • GIS Data

Monterey, 2002
Includes:

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

Oceanside, 2007
Includes:

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

San Diego, 2008
Includes:

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

RGM 1:250,000 Scale Maps

Chico, 1992
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
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
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
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
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
Includes:

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

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.