THE FOX RANGE FAULT SCARP: AGE DETERMINATION BY SOIL COHESION AND WALLACE METHODS

Studies in fault scarp morphology, by Wallace (1977) and others, have shown scarp profile characteristics to be useful parameters in fault scarp age determination. The present study applies the Wallace method to a fault scarp in northwestern Nevada. In addition, a second method, involving soil cohesion measurements, is also developed and applied in an attempt to test the validity of the Wallace method. The fault, termed the Fox Range Scarp, is exposed for approximately 10.5 miles in poorly consolidated alluvial fan material and is produced by normal dip-slip movement, exhibiting a maximum vertical displacement of about 2.5 meters. The scarp slopes, ranging from 20 deg to 30 deg and controlled primarily by debris and wash processes, are according to Wallace, indicative of a 2,000 year old fault scarp. Soil cohesion measurements suggest 2,000 years to be excessive, but clearly indicate the scarp to be greater than a few hundred years in age. A compromise between the two methods gives a probable age on the order of 500 to 1,000 years. A Richter magnitude of 6.9 is estimated for the earthquake which produced the fault. The Wallace method, as well as the soil cohesion approach to age determination, have site-specific variables which complicate their application and results. It is recognized that no method is without unresolved difficulties and errors, necessitating the use of more than one approach. Soil cohesion is proposed as a new, potentially useful check on the Wallace method, warranting further study and application. (Author)

• Supplemental Notes:
  • Proceedings of the Eighteenth Annual Engineering Geology and Soils Engineering Symposium, held at the Red Lion Inn, Boise, Idaho.
• Corporate Authors:

  Idaho Transportation Department

  3311 W State Street, P. O. Box 7129
  Boise, ID  United States  83707-1129

  University of Idaho, Moscow

  Department of Geology and Geological Engineering
  Moscow, ID  United States  83844-3025

  Boise State University

  Department of Geology and Geophysics
  Boise, ID  United States 

  Idaho State University, Pocatello

  Department of Geology
  Pocatello, ID  United States  83201

  Idaho State University, Pocatello

  Department of Geology
  Pocatello, ID  United States  83201
• Authors:
  • Inghram, B J
  • Klimberg, D M
  • Metcalf, L A
• Conference:
  • Proceedings of the Eighteenth Annual Engineeing Geology and Soils Engineering Symposium, held at the Red Lion Inn, Boise, Idaho.
• Publication Date: 1980-4

Media Info

• Features: Figures; References;
• Pagination: p. 99-113

Subject/Index Terms

• TRT Terms: Age; Cohesion; Fault location; Measurement; Morphology; Soil mechanics
• Uncontrolled Terms: Site investigation
• Subject Areas: Geotechnology; Highways; I42: Soil Mechanics;

Filing Info

• Accession Number: 00334061
• Record Type: Publication
• Files: TRIS, STATEDOT
• Created Date: Sep 16 1981 12:00AM