Volcanoes

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Volcanoes
Current eruptions
http//volcano.und.nodak.edu/vwdocs/current_volcs/
current.html
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Types of Volcanoes

• Cinder Cone
• a. Simplest type of volcano
• b. Bowl shaped crater at dome
• c. Violent explosions releasing cinders
• d. Continually growing and adding material

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Parícutin Volcano, Mexico, is a cinder cone
rising approximately 1,200 feet above the
surrounding plain.
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• Composite or stratovolcanoes
• a. Steep-sided symmetrical cones
• b.

alternating layers of lava flows, volcanic ash,
cinders, blocks, and bombs and may rise as much
as 8,000 feet above their bases

• Mount Fuji in Japan,
• Mount Cotopaxi in Ecuador,
• Mount Shasta in California,
• Mount Hood in Oregon, and
• Mount St. Helens and Mount Rainier in
  Washington.

Schematic representation of the internal
structue of a typical composite volcano.
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Shishaldin Volcano, an imposing composite cone,
towers 9,372 feet above sea level in the Aleutian
Islands, Alaska.
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• Erosion destroys cone as volcano becomes dormant.
• Hardened magma becomes exposed
• All that remains is plug and dike projecting
  above the ground
• Caldera collapse of a volcano
• ex. Crater Lake Oregon
• Shield volcano
• a. Built entirely by fluid lava flows
• b. Slow build up of material
• c. Kilauea and Mauna Loa on the island of
  Hawaii
• Mauna Loa 13,000 ft above sea level
  and 15,000 ft below

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Hawaii Black Sand Beach
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Diamond Head, HI
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Oahu
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Oahu
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• Types of lava
• a. Aa formed from fast flowing lava
• free chunks of angular pieces
  of lava
• b. Pahoehoe slow flowing lava
• smooth or ropy
  surface
• gentle slopes
• c. Pillow lava submarine eruptions
• Lava tubes lava cooled on outside and continued
  to flow on
• inside to form cave.

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