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Plate tectonics

Plate tectonics. Alfred Wegner. In 1912, he realized that the coastlines of South America and Africa seemed to “fit” together. Imagine a puzzle. Then he collected rocks and fossils from both continents. They were the same!. Seafloor spreading.

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Plate tectonics

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  1. Plate tectonics

  2. Alfred Wegner • In 1912, he realized that the coastlines of South America and Africa seemed to “fit” together. • Imagine a puzzle. • Then he collected rocks and fossils from both continents. • They were the same!

  3. Seafloor spreading • The seafloor spreads apart at Mid ocean ridges. • At these volcanic areas, Igneous rock cools quickly. • Iron particles are “frozen” into alignment, since the magnetic poles change over time, these stripes show that the ocean has spread over time.

  4. Plate boundaries- • area or margins along which plates meet and interact. • Characterized by frequent major geologic activity (earthquakes and volcanoes) • Use chart on pg. 5 ESRT

  5. Subduction Zone

  6. Divergent boundary

  7. Convergent Boundary

  8. What “drives” this process? • Convection currents in the asthenoshpere. • Materials that are heated are less dense therefore they rise. • Materials that are cooler are more dense therefore they sink.

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