What????

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What????
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The DeLorean Time Machine
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Drifting ApartThe Theory of Continental Drift
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Whats the meaning of Continental Drift?

• Earths crust is constantly moving
• horizontal
• vertical
• Crust is drifting on top of the mantle
  (asthenosphere)
• Two types of crust
• Continental and Oceanic
• Shape and location of the continents and oceans
  have changed over millions of years (Constructive
  Destructive Forces)

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Alfred Wegener

• He hypothesized about 300 MYA the Earth had only
  one giant continent called Pangaea (meaning all
  lands)
• Published The Origin of Continents and Oceans in
  1915
• Evidence supporting the theory
• Puzzle-Like Fit
• Fossil records
• Rock sequences
• Climates and changing polar regions
• Mountain Ranges

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Alexander Du Toit

• Proposed that 200 M.Y.A., Pangaea broke up into
  two supercontinents
• Gondwanaland
• S.A., Africa, Antarctica, Australia, India
• Laurasia
• N. A., Eurasia (Europe and Asia)
• Pangaea was surrounded by a sea called
  Panthalassa

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Evidence for Continental Drift

• Evidence 1 Puzzle-Like Fit
• Matching coastal lines fit together like a jigsaw
  puzzle
• South America Africa

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Evidence for Continental Drift cont.

• Evidence 2 Fossil Clues
• Similar fossils found on several different
  continents
• Separation by oceans suggests that the continents
  were once connected
• Glossopteris fern (southern continents)
• Cynognathus land reptile (S.A. Africa)
• Lystrosaurus land reptile (Africa, Antarctica,
  India)
• Mesosaurus freshwater reptile (S.A. Africa)

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Evidence for Continental Drift cont.

• Evidence 3 Rock Types
• Similarities in rock types found in S.A., Africa,
  India, Antarctica, and Australia
• Paleomagnetism
• Study of the magnetism of ancient rocks and
  sediments

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Continental Drift Evidence

• Evidence 4 Climate Clues
• Continental ice sheets and glacial markings in
  South Africa
• Fossils of tropical plants found in Spitsbergen
  (small island north of Norway)
• Suggests movement from the equator and the poles

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Continental Drift Evidence

• Evidence 5 Mountain Ranges
• Similar mountain ranges
• Argentina and South Africa

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Theory Rejected

• Wegener could not explain the forces that push or
  pull the continents
• Geologists rejected his theory of continental
  drift
• Lacked information on formation of mountains and
  continents
• Then new evidence was discovered
• As a Jr. Geologist, what kind of forces (give
  examples) do you infer could be used to push
  and pull the continents around???

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Can you G.R.A.S.P. Continental Drift?

• G
• R
• A
• S
• P