The following Geologic Maps are available on-line from CGS. Each map will open in a new window with the map overlaid on base map images from Google Maps. The transparency of the geologic map can be adjusted and the Google maps background can be changed using the slider and buttons in the upper right corner. All maps will allow the user to zoom in and pan across to see the geology depicted with as much detail as the original maps will allow. If the user zooms in beyond the appropriate scale for the original map, the map image will no longer appear.
New editions of the Geologic Map of California and the Fault Activity Map of California have been prepared in recognition of the California Geological Survey’s 150th Anniversary.
The Geologic Atlas of California was published between 1958 and 1969. 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. Although more recent and more detailed mapping is available in many areas, this set of maps is still the most detailed interpretation available for the entire state. The index map below shows the areas covered by the individual sheets of the Geologic Atlas.
In an effort to include new geologic mapping completed after publication of the Geologic Atlas of California, CGS began compiling a new Regional Geologic map series at the same scale as the Geologic Atlas. The first of this new series was published in 1981. The Regional Geologic Maps are the same scale and cover the same areas as the previous Geologic Atlas, 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. CGS has published four Regional Geologic maps at 1:100,000 scale and is working on several others. See the Preliminary Geologic Maps page for maps in progress.