View of Oregon Volcanoes of the Cascade Arc, looking north.
The Cascades Volcanoes are products of subduction above the Juan de Fuca Plate beneath North America --and so form a line that is inland but roughly parallel to the subduction zone. The volcanoes extend from northern California to southern British Columbia, and consist of mostly of basalt, basaltic andesite, andesite, and dacite. This photo, from the summit of Collier Cone, shows several of the Oregon Volcanoes, beginning with Belknap Shield Volcano on the far left, then Mt. Washington, Three Fingered Jack, Mt. Jefferson, (the very prominent one, just left-of-center), and Mt. Hood (it looks smaller, but it's much farther away). Other basaltic volcanoes are on the right side, including Black Crater and Black Butte.

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