Volcanoes of the Northern Oregon Cascade Range
January 26, 2023
Photographer: Marli Miller
Summary Author: Marli Miller
The Cascade Volcanoes form a linear chain that runs north-south from northern California to southern British Columbia. They form a line because they’re fed by magma that originates by subduction of the Juan de Fuca Plate beneath North America -- and the subduction zone trends north-south (see schematic figures below).
This photo shows part of the volcanic chain, from South Sister northward to Mts Jefferson and Hood; Mt. Adams in Washington appears faintly on the horizon. Two rhyolitic lava flows, erupted between 2000-2300 years ago, appear on the flanks of South Sister. Notice also the many smaller peaks and cones. The Oregon Cascades hosts more than a thousand volcanic vents that have erupted in the last 2 million years. These vents are mostly basaltic in composition but include andesitic and rhyolitic ones as well. Photo taken on December 16, 2022.
Oregon’s Cascade Range Coordinates: ~44.000, -121.900
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