Birth of a Volcano

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Birth of a Volcano
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What Causes Volcanoes?

• Effects of Plate Tectonics
• Forces from Within the Earth

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Plate Tectonics
Plate Tectonics, theory that the outer shell of
the earth is made up of thin, rigid plates that
move relative to each other.
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Tectonic Plates
Tectonic plates are made of either oceanic or
continental crust and the very top part of the
mantle, a layer of rock inside the earth.
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As the plates move, weak areas in the crust are
created allowing molten rock, or magma, to well
up to the earths surface.
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Forces from Within the Earth
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Anatomy of a Volcano
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Where Volcanoes Occur
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Changes Caused by Volcanoes

• Physical Changes to the Earth
• Environmental Changes

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Physical Changes

• New Land
• Islands in the Ocean
• Mountains and Plains

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Environmental Changes

• Initial impact
• destroys living environment

Long-term effects slow recovery new ecosystem
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Important Terms

• Plate Tectonics
• Tectonic Plates
• Continental Crust
• Ocean Crust
• Lithosphere
• Mantle
• Ring of Fire

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Volcano Quiz

• 1. What are tectonic plates?
• 2. Where do most volcanoes occur?
• 3. What is magma?
• 4. What is a hot spot?
• 5. Name one physical change and one
  environmental caused by volcanoes.

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References

• http//pubs.usgs.gov/publications/text/dynamic.htm
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• This dynamic earth example and sources
• http//encarta.msn.com/find/Concise.asp?ti00C4800
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• Encarta brief descriptions of tectonics,
  plates and related
• http//library.thinkquest.org/17457/english.html
• Volcanoes web page
• http//www.thinkquest.org/library/lib/site_sum_out
  side.html?tname17457url17457/
• Thinkquest activities, volcanoes