Volcanoes

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Chapter 9

• Volcanoes

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Section 1

• _________ mountain that forms when layers of
  lava and volcanic ash erupt and build up

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• Magma is _________ dense than the rock around it,
  so it very slowly rises toward Earths surface

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• _________ opening through which _________ flows
  out on to Earths surface

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• Factors that Affect Eruptions
• 1) Water Vapor and Trapped Gases gas that gets
  trapped under high pressure eventually escapes,
  causing explosive eruptions
• (slow release _________ eruption)

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• 2) Composition of Magma
• A) _________ magma contains little silica, is
  very _________ , and produces quiet, _________
  eruptions

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• B) _________ magma is thick with a lot of silica
  which causes pressure to build, also has a lot of
  water vapor, which causes _________ eruptions

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Section 2
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• _________ opening at the top of a volcanos
  vent

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Types

• _________ Volcano broad volcano with _________
  _________ sides formed by _________ eruptions of
  basaltic lava
• Ex. Hawaiian Islands

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• _________ _________ Volcanoes _________ ,
  loosely consolidated volcano formed from falling
  tephra
• Tephra lava erupted into the air and cooled also
  known as _________

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• _________ Volcano cycle of lava and tephra is
  repeated over and over at convergent boundaries
  above subduction zones

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Formations

• Batholiths largest intrusive igneous rock body
  formed when huge bodies of magma cool underground
  and stop rising
• Ex. Granite domes (Yosemite National Park)

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Formations

• Dike magma that is squeezed into a vertical
  crack and hardens

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Formations

• Sill magma that is squeezed into a horizontal
  crack and hardens

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Formations

• Laccolith dome of rock formed when magma that
  forms a sill may continue to push the rock layers
  upward

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Formations

• Volcanic Neck in a dead volcano, the cone erodes
  away first, leaving behind this solid igneous
  core

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Formations

• _________ after an eruption, the top of a
  volcano may collapse down into the vent, thus a
  very large opening is formed

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Section 3
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Where Do Volcanoes Occur?

• 1) _________ Boundary magma flows from rifts and
  is instantly cooled by seawater. It builds up
  from the seafloor, sometimes rising high enough
  to from islands
• Ex. Iceland

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• 2) _________ Boundaries magma that is created in
  the subduction zone works its way to the surface,
  forming volcanoes
• Ex. Mount Saint Helens

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• Pacific _________ of _________ area around the
  pacific plate where earthquakes and volcanoes are
  common

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• 3) _________ _________ areas in the mantle that
  are hotter than others. The melted rock rises
  toward the crust as magma

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• Ex. Hawaiian Islands
• (plate is moving but hot spot is stationary)

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Additional Information

• Geothermal Energy heat from magma can be used to
  heat water and produce steam in a power plant,
  the steam is pressurized and spins generators
  that make electricity

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Additional Information

• Would it be better to clear forests for
  geothermal energy or to continue releasing
  pollution into the atmosphere?