Preliminary Geologic Map of the Perris 7.5? Quadrangle, Riverside County, California

The Geologic Map of the Perris 7.5? Quadrangle, Riverside County, California contains a digital geologic map database of the Perris 7.5? quadrangle, Riverside County, California that includes: 1. ARC/INFO (Environmental Systems Research Institute, "http://www.esri.com") version 7.2.1 coverages of the various elements of the geologic map. The Correlation of Map Units and Description of Map Units is in the editorial format of USGS Geologic Investigations Series (I-series) maps but has not been edited to comply with I-map standards. Within the geologic map data package, map units are identified by standard geologic map criteria such as formationname, age, and lithology. Where known, grain size is indicated on the map by a subscripted letter or letters following the unit symbols as follows: lg, large boulders; b, boulder; g, gravel; a, arenaceous; s, silt; c, clay; e.g. Qyfa is a predominantly young alluvial fan deposit that is arenaceous. Multiple letters are used for more specific identification or for mixed units, e.g., Qfysa is a silty sand. In some cases, mixed units are indicated by a compound symbol; e.g., Qyf2sc. [Summary provided by the USGS.]