Continental Drift

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Continental Drift

• What evidence do scientists have to support the
  fact that the Earths crust is continuously
  moving?

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1500s Abraham Ortelius

• Saw that the coastlines of Africa and the
  Americas looked similar
• Concluded they must have once fit together
• Broke apart due to floods, earthquakes and
  volcanoes

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1800s Eduard Suess

• Stated that the southern continents were once a
  single landmass called Gondwanaland
• Northern continents called Laurasia

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1900s Alfred Wegener

• Continental Drift
• Hypothesis that Earths continents were joined as
  a single landmass that broke apart about 200
  million years ago (mya)
• Known as Pangaea
• Continents slowly moved to their present locations

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Pangaea - All Earth
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Evidence from Fossils

• Similar fossils of several different plants and
  animals that once lived near each other found on
  widely separated continents
• Land animals did not swim across ocean, so there
  had to be a land connection between continents

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Evidence from Rock Formations

• Similarly, rock formations are similar on distant
  continents
• For example, rock types found in Appalachian
  Mountains similar to those found in Greenland and
  Europe

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Climatic Evidence

• Coal deposits in Antarctica indicate that the
  climate was much warmer in the past
• Must have been located closer to the equator
  before it drifted

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Flaws in Continental Drift Theory

• Wegeners theory of continental drift had some
  notable flaws
• Not able to explain what force was large enough
  to move such large pieces of earth over great
  distances
• Not able to explain how the ocean basins were not
  shattered, despite solid landmasses crossing
  through them

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Review Questions

• What does Pangaea mean in Greek?
• What was Ortelius contribution to Continental
  Drift?
• Who is credited with the theory of Continental
  Drift?
• List and describe the three main evidences for
  Continental Drift.
• What is one major flaw in the theory of
  Continental Drift?