Mount Mazama is a composite volcano. It is made of multiple layers of lava flows and fragmented debris. Mount Mazama had a violent eruption around 5677 B.C., which caused the main height of the volcano to collapse and cr... More »

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Mount Mazama last erupted in 2290 B.C. The eruption was so severe that the volcano collapsed, forming a caldera. This means that during the eruption, the volcano sank into the ground, creating a giant crater. The crater ... More »

Crater Lake in Oregon is 1,943 feet deep, according to the National Park Service. That makes Crater Lake the deepest U.S. lake and the world's ninth deepest. More »

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Mount Mazama last erupted in 2290 B.C. The eruption was so severe that the volcano collapsed, forming a caldera. This means that during the eruption, the volcano sank into the ground, creating a giant crater. The crater ... More »

Mount Vesuvius is a volcano that is roughly 4,300 feet tall, according to About.com's Ancient/Classical History expert. It is located in Italy, near the Bay of Naples. More »

The eruption of Mount St. Helens at 8:32 on May 18, 1980 was a major geological event that continues to have many effects on the 150 square miles surrounding the volcano. This eruption is classified as the worst volcanic... More »

Mount St. Helens is a cinder cone volcano that formed through the gradual accumulation of cinders and ash at the base of the mountain. Unlike a shield volcano, such as Mauna Loa in Hawaii, cinder cones can rise sharply f... More »