Wyeast (Mount Hood) lifts his head in pride, but Klickitat (Mount Adams) wept to see the beautiful maiden wrapped in snow, so he bends his head as he gazes on St. This is one of many indian legends involving Mount St. Although minor steam explosions may have occurred in 1898, 1903, and 1921, the mountain gave little or no evidence of being a volcanic hazard for more than a century after 1857. Intermittent volcanism continued after the glaciers disappeared, and nine main pulses of pre-1980 volcanic activity have been recognized.
Consequently, the majority of 20th-century residents and visitors thought of Mount St. These periods lasted from about 5,000 years to less than 100 years each and were separated by dormant intervals of about 15,000 years to only 200 years.
Helens) was a beautiful, symmetrical cone of dazzling white. The local Indians and early settlers in the then sparsely populated region witnessed the occasional violent outbursts of Mount St. The volcano was particularly restless in the mid-19th century, when it was intermittently active for at least a 26-year span from 1831 to 1857. Helens also was active sporadically during the three decades before 1831, including a major explosive eruption in 1800. Hopson, and their associates, who began their studies in the late 1950's, has particularly advanced knowledge of Mount St. Their systematic studies of the volcanic deposits, laboratory investigations of rock and ash samples, and radiocarbon (carbon-l4) dating of plant remains buried in or beneath the ash layers and other volcanic products enabled them to reconstruct a remarkably complete record of the prehistoric eruptive behavior of Mount St. The oldest ash deposits were erupted at least 40,000 years ago onto an eroded surface of still older volcanic and sedimentary rocks.
Intense earthquake activity persisted at the volcano during and between visible eruptive activity.
As early as March 31, seismographs also began recording occasional spasms of volcanic tremor, a type of continuous, rhythmic ground shaking different from the discrete sharp jolts characteristic of earthquakes.
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. 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.