Geologic and geophysical maps of the El Casco 7.5′ quadrangle, Riverside County, southern California, with accompanying geologic-map database

Open-File Report 2010-1274
By: , and 

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Introduction

Earth materials and structures in the El Casco quadrangle provide considerable information about the late Cenozoic geologic evolution of southern California’s Inland Empire region (fig. 2). Important structural and stratigraphic elements include (1) modern traces of the right-lateral San Jacinto Fault zone, (2) older traces of the San Jacinto Fault zone, and (3) sedimentary materials and geologic structures that formed during the last eight million years or so and that record interactions within the San Andreas Fault system. These materials, and the structures that deform them, provide a geologic context 3 for investigations of groundwater recharge and subsurface flow (Waring, 1919; Burnham and Dutcher, 1960; Bloyd, 1971; Rewis and others, 2006).

This geologic database of the El Casco 7.5′ quadrangle was prepared by the Basins and Landscape Co-Evolution Project (BALANCE), a regional geologic-mapping project sponsored jointly by the U.S. Geological Survey and the California Geological Survey. The database was developed as a contribution to the National Cooperative Geologic Mapping Program’s National Geologic Map Database, and provides a general geologic setting of the El Casco quadrangle. The database and map provide information about earth materials and geologic structures, including faults and folds that have developed in the quadrangle due to complexities in the San Andreas Fault system.

Geologic information contained in the El Casco database is general-purpose data applicable to land-related investigations in the earth and biological sciences. The term “general-purpose” means that all geologic-feature classes have minimal information content adequate to characterize their general geologic characteristics and to interpret their general geologic history. However, no single feature class has enough information to definitively characterize its properties and origin. For this reason the database cannot be used for site-specific geologic evaluations, although it can be used to plan and guide investigations at the site-specific level.

Suggested Citation

Matti, J.C., Morton, D.M., and Langenheim, V.E., 2015, Geologic and geophysical maps of the El Casco 7.5′ quadrangle, Riverside County, southern California, with accompanying geologic-map database: U.S. Geological Survey Open-File Report 2010–1274, 141 p., 3 sheets, scale 1:24,000, http://dx.doi.org/10.3133/ofr20101274.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Geologic Overview
  • Introduction
  • Acknowledgments
  • Quaternary Surficial Materials
  • Cenozoic Sedimentary Materials
  • Depositional History of the San Timoteo and Mt. Eden Formations
  • Crystalline Basement Rocks
  • Structural Geology
  • Geomorphic Features
  • Geophysical Investigations
  • Outline of Geologic History
  • Subsurface Borings and Geotechnical Investigations
  • Description Of Map Units
  • References Cited
  • Appendix 1

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Geologic and geophysical maps of the El Casco 7.5′ quadrangle, Riverside County, southern California, with accompanying geologic-map database
Series title Open-File Report
Series number 2010-1274
DOI 10.3133/ofr20101274
Year Published 2015
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description Report: vi, 141; 3 Sheets: 46.77 x 36.00 inches or smaller; Dataset; Metadata; Read Me
Country United States
State California
County Riverside County
Other Geospatial El Casco 7.5' Quadrangle
Online Only (Y/N) Y
Additional Online Files (Y/N) N