Geologic field-trip guide to Long Valley Caldera, California

Scientific Investigations Report 2017-5022-L
By:  and 



This guide to the geology of Long Valley Caldera is presented in four parts: (1) An overview of the volcanic geology; (2) a chronological summary of the principal geologic events; (3) a road log with directions and descriptions for 38 field-trip stops; and (4) a summary of the geophysical unrest since 1978 and discussion of its causes. The sequence of stops is arranged as a four-day excursion for the quadrennial General Assembly of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI), centered in Portland, Oregon, in August 2017. Most stops, however, are written freestanding, with directions that allow each one to be visited independently, in any order selected.

Suggested Citation

Hildreth, W. and Fierstein, J., 2017, Geologic field-trip guide to Long Valley Caldera, California: U.S. Geological Survey Scientific Investigations Report 2017–5022–L, 119 p.,

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Summary of Volcanic Geology
  • Long Valley Chronology: A Summary Timeline
  • Excursion Logistics and 38 Stops
  • Recent Unrest In and Near Long Valley Caldera
  • Long Valley Geophysical Puzzles
  • Acknowledgments
  • References Cited


  • A Refreshing Overview of the Bishop Tuff, by Wes Hildreth
  • Concealed Ring-Fault Zone of Long Valley Caldera, by Wes Hildreth
  • Overview of the Long Valley Hydrothermal System After Decades of Study, by William C. Evans 

Publication type Report
Publication Subtype USGS Numbered Series
Title Geologic field-trip guide to Long Valley Caldera, California
Series title Scientific Investigations Report
Series number 2017-5022
Chapter L
DOI 10.3133/sir20175022L
Year Published 2017
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Volcano Science Center
Description x, 119 p.
Country United States
State California
Other Geospatial Long Valley Caldera
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details