LANDSLIDING ALONG THE HIGHWAY 50 CORRIDOR: GEOLOGY AND SLOPE STABILITY OF THE AMERICAN RIVER CANYON BETWEEN RIVERTON AND STRAWBERRY, EL DORADO COUNTY, CALIFORNIA

Highway 50 was blocked for 27 days while construction crews removed 350,000 cu yd of landslide debris following the January 24, 1997, Mill Creek Landslide. At the request of the California Department of Transportation, the California Geological Survey mapped the geology and slope stability of the American River Canyon adjacent to Highway 50 for about 15 mi between Riverton and Strawberry, California. The purpose of this geologic mapping was to identify and locate unstable earth materials underlying the slopes of the canyon and to determine the influence of the geology and geologic structure of the area on slope stability. Over 600 landslides were identified. Over 50 of these landslides moved during the winter of 1996-97. The most unstable slopes are between Riverton and Twentynine Mile Station. The rocks have been weakened by deformation and there are masses of unconsolidated, sandy, material that, prior to this study, had not been recognized. Active landslides occur along or near boundaries between different rock types. Landslides were grouped according to their estimated relative stability to aid the California Department of Transportation in setting priorities for mitigation. The area can be subdivided into three domains based on the types and frequency of landslides. Slope inclination, bedrock geology, geologic structure, geomorphology, weathering, vegetation, and precipitation all influence the stability of the slopes along the Highway 50 corridor.

• Supplemental Notes:
  • Unlike most groups and organizations that meet on a regular basis, the Highway Geology Symposium has no central headquarters, no annual fees, and no formal membership requirements. The governing body of the Symposium is a Steering Committee. Recent proceedings may be obtained from the Treasurer of the Symposium, Mr. Russell Glass.
• Corporate Authors:

  Mr. Russell Glass

  100 Wolf Cove Road
  Asheville, NC  United States  28804
• Authors:
  • Wagner, D L
  • Spittler, T E
  • Sydnor, R H
• Conference:
  • Better Highways Through Applied Geology. 53rd Annual Highway Geology Symposium
  • Location: San Luis Obispo, California
  • Date: 2002-8-13 to 2002-8-16
• Publication Date: 2002

Language

• English

Media Info

• Features: Figures; References;
• Pagination: p. 252-263

Subject/Index Terms

• TRT Terms: Canyons; Geology; Geomorphology; Landslides; Mapping; Precipitation (Meteorology); Slope stability; Vegetation; Weathering
• Identifier Terms: Mill Creek Landslide
• Geographic Terms: American River Canyon
• Subject Areas: Geotechnology; Highways; I41: General Soil Surveys; I42: Soil Mechanics; I43: Rock Mechanics;

Filing Info

• Accession Number: 00962028
• Record Type: Publication
• Report/Paper Numbers: CD-ROM
• Files: TRIS
• Created Date: Aug 11 2003 12:00AM