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Continental Drift

Continental Drift. Continental Drift. In 1912, Alfred Wegener developed the theory of continental drift, which states that continents are in constant motion on Earth’s surface. Evidence for Continental Drift. Wegener based his hypothesis on 3 pieces of evidence: 1. Puzzle pieces

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Continental Drift

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  1. Continental Drift

  2. Continental Drift • In 1912, Alfred Wegener developed the theory of continental drift, which states that continents are in constant motion on Earth’s surface.

  3. Evidence for Continental Drift • Wegener based his hypothesis on 3 pieces of evidence: • 1. Puzzle pieces • Continents look like they fit together

  4. Fossil Evidence • 2. The same types of fossils are found on continents separated by vast oceans • Example: Mesosaurus was a freshwater reptile and fossils of it have been found on both South America and Africa. How did it cross the ocean?

  5. Geologic Evidence • 3. Rocks made of similar materials or mountains formed at same time are found on continents that are now far apart

  6. Was Wegener Right? • Many scientists did not agree with Wegener because he could not give evidence as to how the continents move • In the 1960’s new discoveries led scientists to revise Wegener’s hypothesis. • The new theory they came up with is called the Theory of Plate Tectonics.

  7. Plate Tectonics • The theory of plate tectonics says: • Continents do not push their way through the solid rock of the upper mantle, rather the continents are part of plates and the plates slide past or move toward or away from each other. • This movement is driven by convection (heat transfer) in the mantle.

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