This index covers the detailed geologic maps of California which are distributed among the fourteen irregular issued map and monograph series published by the United States Geological Survey. This index was created and is maintained by Joe Crotts, California State University, Chico, Meriam Library. The index correlates U.S.G.S. geologic maps of California with 7.5' and 15' topographic quadrangles. Maps having scales of 1:125,000 and larger are included in the index.

The index is alphabetical by quadrangle name, with 7.5' quadrangles preceding identically named 15' quadrangles. Click on the first letter of the quadrangle name to access quadrangles with names beginning with that letter. Information provided for each quadrangle are: series name and number of each report containing a geologic map of that quadrangle or portion of it, the extent of coverage of the area, and the scale for those maps made after 1981. 

The fourteen U.S.G.S. series containing geologic maps of California are held either in the Map Collection or in Government Documents.