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Continental drift theory


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Continental drift theory

  1. 1. Continental drift theory<br />
  2. 2. According to the hypothesis of continental drift, continents have moved slowly to their current locations.<br />Theory of continental was purposed by alferedwegner in (1912)<br />
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  4. 4. Mechanism for Plate Tectonics<br />Seafloor Spreading provided insight to the mechanism for how the continents moved. <br />The magma which pushes up at the mid-ocean ridge provides the new land pushing the plates, and the subduction zones gobble up the land on the other side of the plates.<br />The mechanism was convection currents!<br />
  5. 5. Thirteen plate on the world<br />
  6. 6. About 225 million years ago , nearly all the land was united in one large land callled<br />Pangaea<br />
  7. 7. Pangaea about 200 million years ago, before it began breaking up. The southern portion of Pangaea Gondwana, and the northern portion Laurasia. <br />
  8. 8. The continents about 70 million years ago. Notice that the breakup of Pangaea formed the Atlantic Ocean. India’s eventual collision with Eurasia would form the Himalayan Mountains<br />
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  10. 10. The position of the continents today. The continents are still slowly moving, at about the speed your fingernails grow. Satellite measurements have confirmed that every year the Atlantic Ocean gets a few inches wider!<br />
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  13. 13. Sea flour spreading<br />As the seafloor spreads apart at a mid-ocean ridge, new seafloor is created. <br />
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  15. 15. Plate tectonic explain<br />Earthquakes<br /> Mountains<br /> volcanoes <br />
  16. 16. Earthquakes and volcanoes occur mostly along or near trenches and mid-ocean ridges...<br />
  17. 17. Mountain formation<br />
  18. 18. Volcanoes<br />
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  20. 20. Thawaearthequakeekkakdanna<br />
  21. 21. Evidence to support the theory<br />
  22. 22. Continental drift fossil evidence<br />
  23. 23. “Puzzle Pieces”<br />Continents look like <br />they could be part of <br />a giant jigsaw puzzle<br />
  24. 24. Distribution of fossils of several organisms supported The theory that the continents were once joined together <br />
  25. 25. Francis Bacon (1561-1626) first noted how coasts of Africa and South America fit.<br />
  26. 26. Mesosaurus, a fresh water reptile that couldn’t swim across the open sea<br />
  27. 27. Sequence of Rocks<br />Same rock patterns found in South America, India, <br />Africa, Antarctica and Australia<br />
  28. 28. Mountains in South America and Antarctica are believed to have formed as part of the same mountain chain. <br />
  29. 29. Ancient Climates<br />Tropical plant remains (coal deposits) found in Antarctica<br />Glaciations in Africa, South America, India, and Australia during the same time<br />
  30. 30. Coal<br />Deposits found inAntarctica.<br />Coal requires a warm, lush climate ===><br />What’s Antarctica like today? ===><br />
  31. 31. Glossopteris, a seedfern whose seeds are too large to be carried far by wind<br />
  32. 32. Fossils of Glossopteris are found in Permian rocks of South Africa, India, Australia, South America, and Antarctica—all regions that were once part of Gondwanaland.<br />
  33. 33. Problems With The Theory<br /><ul><li>No mechanism for movement of continents
  34. 34. Wind and currents could possibly move fossils
  35. 35. Theory was not accepted by scientists</li></li></ul><li>