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. Volcanoes above the subduction zone The volcanoes above the subduction zone include: Silverthrone Caldera Mount Meager massif 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 (Crater Lake) Mount McLoughlin Medicine Lake Volcano Mount Shasta Lassen Peak Black Butte Black Butte (California) See also Astoria Fan Cascade Range Cascadia (region) Cascadia Channel Geology of the Pacific Northwest Neskowin Ghost Forest North Cascades National Park Plate tectonics References External links "Cascadia Peril '09" at dailywireless.org 9.0 Shakemap Scenario The Really Big One – University of California Television Great Earthquakes of the Pacific Northwest – Central Washington University Toast, tsunamis and the really big one | Chris Goldfinger | TEDxMtHood – TEDx Subduction zones Geology of Oregon Geology of Washington (state) Geologic provinces of California Geology of British Columbia Natural hazards in British Columbia Seismic zones of British Columbia Cascade Volcanoes