Cascade Volcanic Arc
The Cascade Volcanic Arc (also known as the Cascades or the Cascade Range) is a major range of volcanoes in southwestern British Columbia, Washington, Oregon, and northern California.
The arc is central to the Cascade Range, a mountain range in the Pacific Northwest. It includes about 20 major volcanoes, among over 4,000 separate volcanic vents.[1]
Twelve volcanoes in the arc are over 10,000 ft (3,000 m) in height, and the two highest, Mount Rainier and Mount Shasta, are over 14,000 ft (4,300 m). By volume, the two largest Cascade volcanoes are the broad shields of Medicine Lake Volcano and Newberry Volcano, which are about 145 mi³ (600 km³) and 108 mi³ (450 km³) respectively.
The volcanism in the arc began about 37 million years ago, but most of the present-day Cascade volcanoes are less than 2 million years old. The most recent major catastrophic eruption in the arc was at Mount St. Helens on May 18, 1980.
The major volcanoes in the arc include Mount Silverthrone, Mount Meager, Mount Cayley, Mount Garibaldi, Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, Mount Adams, Mount Hood, Mount Jefferson, Three Sisters, Broken Top, Mount Bachelor, Newberry Volcano, Mount Thielsen, Mount Mazama (Crater Lake), Mount McLoughlin, Medicine Lake Volcano, Mount Shasta, Mount Tehama and Lassen Peak.
Cascade Volcanic Arc Media
Lassen Peak and Devastated Area from Cinder Cone
Mount Garibaldi as seen from the south
Mount Cayley as seen from its southeast slopes
Overview of Dusty Creek drainage, to the left pyroclastic deposits from Gamma Ridge can be seen.
Ignimbrite deposited by the Lake Tapps eruption that formed the Kulshan caldera.
Cascadia earthquake sources
3,000-foot (910 m) steam plume from Mount St. Helens on May 19, 1982
The caldera of Mount Mazama, filled by Crater Lake
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References
- ↑ Madson J.K. et al 2006. Cenozoic to Recent plate configurations in the Pacific Basin: Ridge subduction and slab window magmatism in western North America. 42 (1). Geological Society of America. pp. 27, 28, 31.
- Harris, Stephen L. 2005. Fire mountains of the West: the Cascade and Mono Lake volcanoes. 3rd ed, Mountain Press Publishing Company. ISBN 978-0-87842-220-3