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 : The most active volcanoes in the chain include Mount 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
erupted catastrophically in 1980
1980 eruption of Mount St. Helens
Cascadia subduction zone