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Parts Of A Volcano
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| Volcanic Cones and Craters
Shapes of volcanoes include composite cones or stratovolcanoes, with steep concave sides such as Mt. St. Helens in the west United States; shield cones have gentle slopes and can be relatively large such as the Hawaiian Islands; and cinder cones as Paricutin in Mexico, with steep slopes made of cinder like materials. Explosive eruptions build up steep-sided cones, while the nonexplosive ones usually form broad, low lava cones. Cones range in height from a few feet to nearly 30,000 feet above their base. Usually the cone has as its apex a cavity, or crater, which contains the mouth of the vent. Such craters are typically less than 1 mile across, but larger craters, called calderas, ranging in diameter from 3 mi to–in a few instances–50 miles, are formed by particularly large eruptions. | |