Cascade Volcanic Arc
The Cascade Volcanic Arc is a continental volcanic arc that extends from northern California to the coastal mountains of British Columbia. The arc consists of a series of Quaternary age stratovolcanoes that grew on top of pre-existing geologic materials that ranged from Miocene volcanics to glacial ice. The Cascade Volcanic arc is located approximately 100 km inland from the coast, and forms a north-to-south chain of peaks that average over 3,000 m (10,000 ft) in elevation. The major peaks from south to north include:
- Lassen Peak and Mt. Shasta (California)
- Crater Lake (Mazama), Three Sisters, Mt. Jefferson, Mt. Hood (Oregon)
- Mt. Adams, Mt. St. Helens, Mt. Rainier, Glacier Peak, Mt. Baker (Washington)
- Mt. Garibaldi and Mt. Meager (British Columbia)
The most active volcanoes in the chain include Mt. St. Helens, Mt. Baker, Lassen Peak, and Mt. Hood. St. Helens captured worldwide attention when it erupted catastrophically in 1980. St. Helens continues to rumble, albeit more quietly, emitting occasional steam plumes and experiencing small earthquakes, both signs of continuing magmatic activity. Most of the volcanoes have a main, central vent from which the most recent eruptions have occurred. The peaks are composed of layers of solidified andesitic to dacitic magma, and the more siliceous (and explosive) rhyolite.
The volcanoes within the subduction zone include:
- Silverthrone Caldera
- Mount Meager
- Mount Cayley
- Mount Garibaldi
- Mount Baker
- Glacier Peak
- Mount Rainier
- Mount St. Helens
- Mount Adams
- Mount Hood
- Mount Jefferson
- Three Sisters
- Newberry Volcano
- Mount Mazama
- Mount McLoughlin
- Medicine Lake Volcano
- Mount Shasta
- Lassen Peak
- Black Butte
Read more about this topic: Cascadia Subduction Zone
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