Overview for geologic field-trip guides to volcanoes of the Cascades Arc in northern California

L.J. Patrick Muffler; Julie M. Donnelly-Nolan; Timothy L. Grove; Michael A. Clynne; Robert L. Christiansen; Andrew T. Calvert; Juliet Ryan-Davis

doi:10.3133/sir20175022k

USGS · sir20175022K

Overview for geologic field-trip guides to volcanoes of the Cascades Arc in northern California

L.J. Patrick Muffler·Julie M. Donnelly-Nolan·Timothy L. Grove·Michael A. Clynne·Robert L. Christiansen·Andrew T. Calvert·Juliet Ryan-Davis

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Abstract

The California Cascades field trip is a loop beginning and ending in Portland, Oregon. The route of day 1 goes eastward across the Cascades just south of Mount Hood, travels south along the east side of the Cascades for an overview of the central Oregon volcanoes (including Three Sisters and Newberry Volcano), and ends at Klamath Falls, Oregon. Day 2 and much of day 3 focus on Medicine Lake Volcano. The latter part of day 3 consists of a drive south across the Pit River into the Hat Creek Valley and then clockwise around Lassen Volcanic Center to the town of Chester, California. Day 4 goes from south to north across Lassen Volcanic Center, ending at Burney, California. Day 5 and the first part of day 6 follow a clockwise route around Mount Shasta. The trip returns to Portland on the latter part of day 6, west of the Cascades through the Klamath Mountains and the Willamette Valley. Each of the three sections of this guidebook addresses one of the major volcanic regions: Lassen Volcanic Center (a volcanic field that spans the volcanic arc), Mount Shasta (a fore-arc stratocone), and Medicine Lake Volcano (a rear-arc, shield-shaped edifice). Each section of the guide provides (1) an overview of the extensive field and laboratory studies, (2) an introduction to the literature, and (3) directions to the most important and accessible field localities. The field-trip sections contain far more stops than can possibly be visited in the actual 6-day 2017 IAVCEI excursion from Portland. We have included extra stops in order to provide a field-trip guide that will have lasting utility for those who may have more time or may want to emphasize one particular volcanic area.

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Source-reported bounding extent: 40.06125658140474° to 42.66628070564928° latitude; -122.64038085937499° to -119.981689453125° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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L.J. Patrick Muffler, Julie M. Donnelly-Nolan, Timothy L. Grove, Michael A. Clynne, Robert L. Christiansen, Andrew T. Calvert, Juliet Ryan-Davis. 2017-08-15. Overview for geologic field-trip guides to volcanoes of the Cascades Arc in northern California. https://doi.org/10.3133/sir20175022k

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