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Continental Drift Chapter 9.1

Continental Drift Chapter 9.1. Proposed by Alfred Wegener in 1912 250 million years ago there was a SUPERCONTINENT called PANGAEA. Pangaea then broke up into. Laurasia Gondwanaland. Pangaea splits to form:. Laurasia = Europe, Asia, & North America

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Continental Drift Chapter 9.1

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  1. Continental DriftChapter 9.1

  2. Proposed by Alfred Wegener in 1912 • 250 million years ago there was a SUPERCONTINENT called PANGAEA

  3. Pangaea then broke up into • Laurasia • Gondwanaland

  4. Pangaea splits to form: Laurasia= Europe, Asia, & North America Gondwanaland= South America, Africa, Australia, Antarctica, Madagascar, & India

  5. “PROVE IT!!!!!!!!!!” …and he said “Ok, here’s my 4 forms of evidence” Geologists said…

  6. Evidence to Support Continental Drift

  7. 1. “Puzzle Pieces” • Continents look like they could be part of a giant jigsaw puzzle

  8. 2. Distribution of Fossils • Plant & animal fossils found on the coastlines of different continents

  9. Example: Fossil clues • (Ex. Mesosaurus) -organisms couldn’t swim across. -fossils would have been found all over the globe if they could swim • Critics argued that the animal could have walked across a land bridge • Wegener argued back – if there was a land bridge there would be remnants of it still around - No remnants = no land bridge!

  10. 3.Rock Types & Structures • Several mountain ranges end at one continents edge and reappear at the edge of another continent • What does that imply? • This implies that the continents were once connected

  11. 4. Ancient Climates • Glacial sheets have been found in Africa, South America and other areas • These sheets show that 200-300 mya ice covered these areas. • These areas are very close to the Equator • If the continents have always been at their present locations, it could NEVER have been cold enough for this ice to form • In Pangaea, these areas were close to the Antarctic Pole

  12. They also found coal in Antarctica!* What does that imply? There would have had to have been a forest that grew there. Had to have been warm at some point. At the present location that would be impossible!!

  13. The Geologists reject Wegener’s hypothesis! He hasn’t explained HOW the continents are moving!

  14. Wegener’s evidence was CORRECT!! • He just couldn’t explain HOW the continents moved • He thought the continents just simply floated along on top of the oceans. • NOT TRUE!!!

  15. Technology gets us better info on the ocean floor, earthquakes, and the planet’s magnetic field! A NEW HOPE!!! Leads us to… 1968- The Theory of Plate Tectonics Note: It took 56 years to come up with the new accepted theory. SONAR – bouncing radio waves off of the ocean floor

  16. Plate Tectonics We will cover this tomorrow!

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