Mount Saint Helens


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Saint Helens, Mount,

volcanic peak, 8,363 ft (2,549 m; 9,677 ft/2,950 m before its 1980 eruption) high, SW Wash., historically the most active volcano in the Cascade RangeCascade Range,
mountain chain, c.700 mi (1,130 km) long, extending S from British Columbia to N Calif., where it becomes the Sierra Nevada; it parallels the Coast Ranges, 100–150 mi (161–241 km) inland from the Pacific Ocean.
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. Dormant since 1857, Mt. St. Helens erupted on May 18, 1980, in one of the largest volcanic explosions in North American history; prior to that event there were a series of earth tremors and steam explosions beginning on Mar. 20, 1980. During the eruption a great portion of the rock facing on north side of the mountain fell, followed by a lateral blast of stone, ash, and poisonous gas that carried debris 17 mi (27 km) and flattened and buried surrounding forest. The disaster took some 65 lives, wiped out substantial populations of elk, deer, bear, and coyote, and destroyed 230 sq mi (600 sq km) of vegetation. A volcanic plume rose 80,000 ft (24,400 m) into the air, blanketing a large area of the NW United States with volcanic ash. The symmetrical summit of Mt. St. Helens was replaced by a horseshoe-shaped crater 2,460 ft (750 m) deep. A number of smaller eruptions, beginning on May 25 and continuing into 1986, resulted in lava flows that built up a dome in the crater; a new, dome-building eruption began in 2004. The volcano and surrounding area are now part of Mt. St. Helens National Volcanic Monument and have provided biologists with a unique opportunity to observe ecological succession and the reestablishment of natural habitats.

Bibliography

See S. A. Kellar, ed., Mount St. Helens (1982); S. Olson, Eruption (2016).


Mount Saint Helens:

see Saint Helens, MountSaint Helens, Mount,
volcanic peak, 8,363 ft (2,549 m; 9,677 ft/2,950 m before its 1980 eruption) high, SW Wash., historically the most active volcano in the Cascade Range. Dormant since 1857, Mt. St.
..... Click the link for more information.
.
References in periodicals archive ?
The rock plugging up Mount Saint Helens formed when molten magma flowing up the volcano cooled and hardened before reaching the top.
The rock that's plugging up Mount Saint Helens is formed by
Since then, Mount Saint Helens has been in what scientists call an active stage, or a long period of time during which a volcano sporadically erupts.
natural history occurred -- as Mount Saint Helens in Washington state erupted, sending steam and ash more than 11 miles into the sky.
JOHAN VAREKAMP, professor of earth and environmental sciences at Wesleyan University, is an expert on Mount Saint Helens.