Plate Tectonics

Plate Tectonics - Katie-Beth Moore John Mason December 3,...

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Katie-Beth Moore John Mason December 3 , 2007 Geo101-008 David Slavic Plate Tectonics Once called a “super continent ,” Pangaea, began breaking apart 200 million years ago . This was the beginning of plate tectonics . Alfred Wagner was the first to come up with the theory of plate tectonics , hypothesizing the continents had “drifted” to their present locations . Evidence to support this theory is the borders of all the continents and their ability to “fit” together as well as rocks , fossils, and structural similarities of the continents . Plate tectonics is only a theory , but is widely accepted and studied today to explain the movement of the earth’s lithosphere . The major components of the “drifting” plates are the lithosphere and the asthenosphere . The lithosphere is the “top layer” containing the continents and the ocean basins . This layer “floats” over a softer , more fluid rock located under the crust called the asthenosphere . When the plates are moving , three different kinds of boundaries can be formed . A divergent boundary is the spreading apart of two plates creating an opening , or rift, in the earth’s surface. The second kind of boundary is a convergent boundary . This is when two plates are being forced together and colliding . An example of this can be the formation of mountains . However , in some cases, if a more dense rock
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is being subducted beneath a lighter continental rock , a trench can form. The third type of plate boundary is a transform fault , where the plates are moving sideways in relation to each other . The most common example of this is an earthquake where force and stress is built up between plates . By studying these different kinds of boundaries and how they work with the lithosphere and asthenosphere , scientists are able to explain the results of plate tectonics . The Earth consists of seven major plates: Pacific
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Plate Tectonics - Katie-Beth Moore John Mason December 3,...

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