What process formed mount st. Helens?

Answer 1

Mount St. Helen's formed about 40,000 years ago, and the pre-1980 summit cone began rising about 2,200 years ago. Prior to the 1980 eruption, Mount St. Helens was the fifth-highest peak in Washington.

Answer 2

Mt. St. Helens was formed as part of the Cascade Volcanic Arc. This volcanic arc extends from Northern California well north into Canada. This volcanic arc is the result of the subduction of the Juan De Fuca tectonic plate off the coast of these areas. The volcano results when the plate is subducted under North America and than partially melts at depth within the mantle. This process results in the formation of volcanoes normally about 60 miles from the coast where the plate goes deep enough to spark the melting process. The process forms magma that once fluid enough will rise to the surface resulting in the formation of the volcanoes found in the area. For further information on this subject please refer to the related links to the website for the Cascades Volcano Observatory.

Answer 3

Mount St. Helens is part of a group of volcanoes called the Cascade Volcanic Arc. This arc has formed as a slab of oceanic crust has slid under the North American Plate. Water that it takes with it has altered the chemistry of the hot mantle rocks, allowing them to melt and rise through the crust. This molten rock has erupted onto the surface in places to form volcanoes. The mountain itself is formed from ash and cooled lava flows that have piled up on top of each other. It is a rather violent volcano that has blown itself apart and built back up several times in its history. The current appearance of the volcano is largely due to the large eruption in 1980 which removed the mountain's summit and northern slope, leaving the characteristic horseshoe-shaped crater. Within the crater is a pile of rock called a lava dome which has been built up by less violent eruptions since 1980.

Answer 4

with a bush of rocks form togerther.And lava hardening togerther.

Answer 5

Two plate boundary's collided, one went underneath the other pushing up the magma forming the volcano. This is also how hills are formed