Mt St Helens geologic history

Taken directly from: Mt. St Helens.com

"Mount St. Helens, located in southwestern Washington about 50 miles northeast of Portland, Oregon, is one of several
lofty volcanic peaks that dominate the Cascade Range of the Pacific Northwest; the range extends from Mount
Garibaldi in British Columbia, Canada, to Lassen Peak in northern California. Geologists call Mount St. Helens a
composite volcano (or stratovolcano), a term for steepsided, often symmetrical cones constructed of alternating layers
of lava flows, ash, and other volcanic debris. Composite volcanoes tend to erupt explosively and pose considerable
danger to nearby life and property. In contrast, the gently sloping shield volcanoes, such as those in Hawaii, typically
erupt nonexplosively, producing fluid lavas that can flow great distances from the active vents. Although Hawaiian-type
eruptions may destroy property, they rarely cause death or injury. Before 1980, snow-capped, gracefully symmetrical
Mount St. Helens was known as the "Fujiyama of America." Mount St. Helens, other active Cascade volcanoes, and
those of Alaska form the North American segment of the circum-Pacific "Ring of Fire," a notorious zone that produces
frequent, often destructive, earthquake and volcanic activity."