Plate Tectonics <br />
Alfred Wegener<br />German geologist 100 years ago<br />Noticed the continents looked like a jigsaw puzzle<br />He thought...
Continental Drift Theory<br />http://www.eduplace.com/kids/socsci/ca/books/bkf3/imaps/AC_01_005_drift/AC_01_005_drift.html...
Evidence for Continental Drift<br />Mountains on east coast of South America are the same rocks as mountains on west coast...
Evidence for Continental Drift<br />Fossils were found of a freshwater reptile Mesosauras have been found in old rocks in ...
Evidence- ocean floor spreading<br />The ocean between South America and Africa spreads 4 centimeters every year.<br />Thi...
Plate Tectonics<br />When Wegener thought of his theory, he didn’t understand how the Earth’s crust could move around.  <b...
Plate Tectonics- Ocean spreading<br />Magma pushes up and forms new land<br />Causes tension (push/pull) on plate<br />Pus...
Plate Tectonics- mountain building<br />Fold mountains<br />Compression = squeeze/pushing together<br />Example: Himalayan...
Plate Tectonics- mountain building<br />Fault-block mountains<br />One plate rubs past each other causes a shear (force th...
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Plate tectonics

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Plate tectonics

  1. 1. Plate Tectonics <br />
  2. 2. Alfred Wegener<br />German geologist 100 years ago<br />Noticed the continents looked like a jigsaw puzzle<br />He thought millions of years ago Earth’s continents were joined together <br />
  3. 3. Continental Drift Theory<br />http://www.eduplace.com/kids/socsci/ca/books/bkf3/imaps/AC_01_005_drift/AC_01_005_drift.html<br />
  4. 4. Evidence for Continental Drift<br />Mountains on east coast of South America are the same rocks as mountains on west coast of Africa<br />Rocks are the same age<br />
  5. 5. Evidence for Continental Drift<br />Fossils were found of a freshwater reptile Mesosauras have been found in old rocks in South America and Africa<br />That animal couldn’t swim across the ocean, so the land must have been connected<br />
  6. 6. Evidence- ocean floor spreading<br />The ocean between South America and Africa spreads 4 centimeters every year.<br />This matches the Continental Drift Theory- 130 million years X 4 cm = 520,000,000 cm <br />This is the width of the South Atlantic Ocean<br />
  7. 7. Plate Tectonics<br />When Wegener thought of his theory, he didn’t understand how the Earth’s crust could move around. <br />Earth’s continents sit on plates of solid rock <br />The asthenosphere (almost melted rock) acts as a slippery surface the plates move around on<br />
  8. 8. Plate Tectonics- Ocean spreading<br />Magma pushes up and forms new land<br />Causes tension (push/pull) on plate<br />Push causes the ocean floor apart and separates plates on either side of the mid-ocean ridge<br />
  9. 9. Plate Tectonics- mountain building<br />Fold mountains<br />Compression = squeeze/pushing together<br />Example: Himalayan mountains<br />
  10. 10. Plate Tectonics- mountain building<br />Fault-block mountains<br />One plate rubs past each other causes a shear (force that twists, tears, pushes past each other) <br />Example: Grand Teton Mountain Range<br />

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