Ch 10 Volcanoes

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Ch 10 Volcanoes

• Volcano- vent in the Earths surface that often
  forms a mountain when layers of lava volcanic
  ash erupt build up

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What causes a Volcano?

• Heat pressure cause rock to melt deep within
  the Earth
• magma is formed
• magma is less dense than rock around it rises

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Parts of a Volcano

• B. Vent opening in Earths surface that
  molten rock comes out of

C. Crater steep walled depression around
a volcanos vent
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D. Hot Spots

• Areas where magma from deep in Earths mantle
  has melted through the crust to form several
  volcanoes

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Ex. The Hawaiian Island chain

• the Pacific Plate is moving over a stationary hot
  spot
• Kauai is the oldest

• Loihi an underwater volcano will form the next
  island in the chain

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E. Caldera

• Formed when the top of a volcano collapses into
  the partially emptied magma chamber
• Produces a large opening
• Ex. Crater Lake in Oregon

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VI . Plutons

• igneous rock (intrusion) that cools inside other
  rock

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Types of Plutons

• Dikes vertical intrusion that cuts across
  layers, rock types do not match
• Batholiths largest igneous intrusions, forms
  when magma cools underground before reaching the
  surface

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Types of Plutons

• 3. Sills form when magma squeezes into
  horizontal cracks hardens
• 4. Laccolith domed sill, that has pushed up the
  rock above it

Stone Mt., Georgia
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Types of Plutons

• 5. Volcanic neck the hard solid vent of a
  volcano left behind after the cone erodes
• Ex. Ship Rock New Mexico Devils Tower

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Mt. Vesuvius, Pompeii, Italy 79 AD
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Mt. Vesuvius, Pompeii, Italy 79 AD