Volcanoes

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Volcanoes

• What are they
• Where do they come from

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Volcanic Rocks

• Rhyolite
• Andesite
• Basalt

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Molten Rock

• Lava flows
• Magma

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Magma

• Low silica content (mafic)
• Thinner
• Dark in color
• Flow easy

• High silica content (felsic)
• Moves slow
• Thick
• Light colored

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Gases in Magma

• Important gases
• Water vapor
• Carbon Dioxide
• Sulfur
• Other gases
• Hydrogen Atmospheric Oxygen
• This produces more steam
• Chlorine and flourine

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Dangerous Gases

• Sulfur Hydrogen and Oxygen
• Produces
• Hydrogen sulfide
• Sulfur Dioxide

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Lava

• Aa lava flows
• Rough jagged surfaces

• Pahoehoe lava flow
• Smooth rope like surface

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Lava Fragments

• Tephra (Ash) less then 2 mm
• Lapilli up to 64 mm
• Blocks more than 64 mm
• Bombs ejected liquid that hardens

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Ash
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Lapilli
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Blocks
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Bombs
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Three types of volcanoes

• Shield Volcano
• Composite Volcano
• Cinder Volcano

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Shield volcano

• Quiet
• Form flat layers
• Lava spreads over a large area
• Mauna Loa is the largest one

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Mauna Loa
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Composite volcano

• Alternate between quite and explosive
• Mt. Vesuvius and Mt. Etna, in Italy are the most
  famous composite volcanoes

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Mt. Vesuvius
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Mt Etna
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Cinder Volcano

• Form from highly explosive eruptions
• Throwing tephra into the air
• When this falls it forms steep sides with a
  narrow base

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Sunset crater Volcano
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Dikes
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You need to find

• Plutons
• Dikes
• Sills
• Laccoliths
• Volcanic neck
• Batholiths
• Stocks

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What is this?