Compiled by V.R. Todd
Open-File Report 2004-1361 Detailed Description of Map Units, version 1.0
The El Cajon quadrangle is one of about 20 1:100,000-scale topographic quadrangles in southwestern California being mapped and compiled by geologists of the U.S. Geological Survey and California Geological Survey as part of the Southern California Areal Mapping Project (SCAMP) and STATEMAP. Sources used for compilation of the El Cajon quadrangle include unpublished mapping at 1:24,000 scale, and unpublished reconnaissance mapping. This report consists of a geologic map, a brief regional synthesis, and descriptions of map units. Geologic interpretations were aided by U-Pb ages for plutonic and volcanic rocks determined by D.L. Kimbrough, G.H. Girty, and C.T. Herzig at San Diego State University. Plutonic rock names were assigned based upon modal analyses and the International Union of Geological Sciences rock classification (Streckeisen, 1973). |
Image Overlay
