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Volcanoes

Volcanoes. 8 th grade Earth Science. There are three types of volcanoes:. Shield Composite Cindercone. SHIELD VOLCANOES. Formed by layer after layer of lava. Usually have low silica content, and gases can escape easily. Has quiet eruptions. Extremely broad and flat in shape.

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Volcanoes

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  1. Volcanoes 8th grade Earth Science

  2. There are three types of volcanoes: • Shield • Composite • Cindercone

  3. SHIELD VOLCANOES • Formed by layer after layer of lava. • Usually have low silica content, and gases can escape easily. • Has quiet eruptions. • Extremely broad and flat in shape. • Found in Hawaii.

  4. SHIELD VOLCANOES • Shield volcanoes have gently sloping sides that can stretch for miles. • These pictures are Mauna Loa, a volcano on the Big Island of Hawaii.

  5. A typical Hawaiian Eruption

  6. COMPOSITE VOLCANOES • Can sometimes be called Stratovolcanoes. • Formed by alternating layers of lava flow and cinders or ash. • Has a high silica content and gases are usually trapped. • Has explosive eruptions. • Mount St. Helens and Mount Rainier in Washington.

  7. COMPOSITE VOLCANOES • Mt. Mayon, Phillippines (left) • Arenal, Costa Rica (below) • Mt. Rainier, Washington (bottom, left)

  8. Mount St. Helens ( COMPOSITE) 1980 2000

  9. Eruption of Mt. St. Helens VIDEO

  10. Mt. St. Helens (COMPOSITE) • Virtual Tour of Mt. St. Helens • Harry Truman – the man who refused to leave “his” mountain.

  11. CINDERCONE VOLCANOES • Formed by layers of cinders and ash, not a lot of lava erupts from these volcanoes. • Very explosive when it erupts. • Has trapped gases. • The shape is nearly perfect on all sides… almost like an orange road pylon.

  12. CINDER CONE VOLCANOES

  13. Psricutin, Mexico (CINDERCONE) • This eruptions that created Paricutin began in 1943 and continued to 1952. Most of the explosive activity was during the first year of the eruption when the cone grew to 1,100 feet (336 m). The cone continued to grow for another 8 years but added only another 200 feet.

  14. Mt. Etna, Italy (COMPOSITE) • In mythology, Etna was identified as the location of the forge of Volcan, home of the Cyclopses, and where the giant Enceladus laid (eruptions being his breath and earthquakes being his motion). Etna’s beauty, frequent eruptions, and long record of eruptions makes it one of the world’s best know volcanoes.

  15. City of Pompeii, Mt. Vesuvius(COMPOSITE)

  16. Images of Pompeii

  17. Devils Tower/Ship Rock • Both pictures are the remaining core of the volcanic neck of a once active volcano. • Located in Wyoming (left) • Ship Rock, San Juan County New Mexico (below)

  18. Latest Eruptions • Mt. St. Helens has been periodically erupting for the 2 years. It is building its peak back up --- slowly but surely.

  19. Latest Eruptions • Montserrat Volcano in the Caribbean. A large explosion and dome collapse occurred on March 3, 2004, causing a high eruption column and basal surge.

  20. Latest Eruptions Etna Volcano in Sicily Late October, 2002

  21. Materials thrown out of a volcano • Lava – molten rock that oozes out of volcanoes. • Tephra • Ash – smallest sized tephra • Cinders – small pieces of cooled lava up to the size of a basketball. • Bombs – any projectile bigger than a basketball.

  22. ASH – the smallest size tephra • Volcanic ash can cover areas like a snow storm

  23. Lava Ash

  24. Lava Cinders

  25. Bombs – cinders usually come out in a pyroclastic flow

  26. Lava Bombs

  27. Types of lava • Aa – Thick, chunky and difficult flow • Pahoehoe – Thin, watery, and easily flows

  28. Lava Flows

  29. Dante’s Peak Eruption… • video

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