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Birth of a Volcano
What Causes Volcanoes?
• Effects of Plate Tectonics
• Forces from Within the Earth
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.
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.
As the plates move, weak areas in the crust
are created allowing molten rock, or
magma, to well up to the earth’s surface.
Forces from Within the Earth
Anatomy of a Volcano
Where Volcanoes Occur
Changes Caused by Volcanoes
• Physical Changes to the Earth
• Environmental Changes
Physical Changes
• New Land
• Islands in the Ocean
• Mountains and Plains
Environmental Changes
• Initial impact
• destroys living
environment
Long-term effects
slow recovery
new ecosystem
Important Terms
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Plate Tectonics
Tectonic Plates
Continental Crust
Ocean Crust
Lithosphere
Mantle
“Ring of Fire”
Volcano Quiz
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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.
References
• http://pubs.usgs.gov/publications/text/dynamic.html
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This dynamic earth; example and sources
• http://encarta.msn.com/find/Concise.asp?ti=00C48000
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Encarta – brief descriptions of tectonics, plates and
related
• http://library.thinkquest.org/17457/english.html
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Volcanoes web page
• http://www.thinkquest.org/library/lib/site_sum_outside.htm
l?tname=17457&url=17457/
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Thinkquest activities, volcanoes