Final answer:
Mount St. Helens is a volcano in Washington state that had a major eruption in 1980. It caused a landslide, destroyed vegetation, and created a crater.
Step-by-step explanation:
Mount St. Helens is a volcano located in Washington state. It had a major eruption in 1980 which caused the mountain's northern slope to collapse, creating a major landslide that wiped out vegetation in the area. The eruption also released carbon-containing gases into the atmosphere. The eruption reduced the elevation of the mountain's summit and left a horseshoe-shaped crater.