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Volcanoes Types of Volcanoes: Cinder Cones, Composite Cones, Shield Volcanoes, and Lava DomesDefinition: Volcanoes are normally cone-shaped hills or mountains formed around vents connecting reservoirs of magma, below the crust. Gas pressure forces molten rock up until it breaks weak spots on the crust. Magma erups and lava flows or gets in the air as ash or dust. Volcanoes grow as they collect debris. Cinder Cones: Cinder Cones are built of lava fragments. They normally have slopes between 30 degrees and 40 degrees and is unusual to find one above 1,640 ft in height. If you've seen either Sunset Crater, Arizona, or Paricutin, Mexico, then you should know how Cinder Cone volcanoes look like. Composite cones: Composite cone volcanoes have layers from lava and ash. Their slopes are nomally 30 degrees at the top, and varying 5 degrees at the base. Have you seen Mt. Fuji, Japan, or Mt. St. Helens, USA? If you have, then you've seen a Composite Cone volcano. Shield Volcanoes: These are mainly made of lava flows. Their slops are rarely more than 10 degrees at the top and 2 degrees at the bottom. Examples of Shield Volcanoes are the ones on the Hawaiian Islands. Lava Domes: They are made of pasty lava squeezed like toothpaste from its tube. Lassen Peak and Mono Dome, California are examples of Lava Domes. The following were the most destructive eruptions since 1700:
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