Field Trip Guide to Mount St. Helens, Washington—Recent and Ancient Volcaniclastic Processes and Deposits

Scientific Investigations Report 2017-5022-E
By: , and 



This field guide explores volcanic effusions, sediments, and landforms at Mount St. Helens in Washington. A detailed synopsis outlines the eruptive history of Mount St. Helens from about 300,000 years ago through 1980 and beyond.

The five days in the field include about 28 stops and 12 potential stops. Exposures in valleys surrounding Mount St. Helens reveal records of diverse Pleistocene and Holocene processes including debris avalanche, lahar, huge water wave on a nearby lake, pyroclastic density currents (surge and flow), tephra fall, lava flow, the growth of domes, and Pleistocene glaciation. Many of the stops explore effects of the several catastrophes that constituted the 18 May 1980 eruption and made Mount St. Helens famous.

Suggested Citation

Waitt, R.B., Major, J.J., Hoblitt, R.P., Van Eaton, A.R., and Clynne, M.A., 2019, Field trip guide to Mount St. Helens, Washington—Recent and ancient volcaniclastic processes and deposits: U.S. Geological Survey Scientific Investigations Report 2017–5022–E, 68 p.,

ISSN: 2328-0328 (online)

Study Area

Table of Contents

  • Introduction—Overview and Background for Days 1–3
  • A Note on Terminology
  • Day 1. Prehistoric Tephra Falls and 18 May 1980 Pyroclastic Surge
  • Day 2. Pre-Eruption Forest, Pyroclastic Surge, Landslide-Made Wave on Spirit Lake
  • Day 3. Prehistoric Falls and Flows on Mount St. Helens’s Southeast and South Flanks
  • Day 4. The Kalama Eruptive Episode and Some Older Features, Southwest and South Flanks
  • Day 4 Road and Trail Stops
  • Day 5. Modern and Ancient Volcaniclastic Sedimentation in Toutle Valley
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Field trip guide to Mount St. Helens, Washington—Recent and ancient volcaniclastic processes and deposits
Series title Scientific Investigations Report
Series number 2017-5022
Chapter E
DOI 10.3133/sir20175022E
Year Published 2019
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Volcano Science Center
Description xii, 68 p.
Country United States
State Washington
Other Geospatial Mount St. Helens
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details