The Theory of Continental Drift

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The Theory of Continental Drift
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Continental Drift Theory

• Proposed by Alfred Wegener in 1912
• 250 million years ago, all of the continents were
  combined into one super-continent called
  Pangaea
• The continents gradually drifted apart to where
  they are today

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Video Link

• Alfred Wegener clip

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Evidence of Continental Drift

• Puzzle Pieces
• Continents look like they could be part of a
  giant jigsaw puzzle
• Continental shelves
• of Africa and South America fit together
  almost perfectly

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Distribution of Fossils

• The Fossil Record
• Glossopteris remains found in SA, Australia,
  Asia, and Africa, Antarctica
• Fossils of deciduous trees found near North Pole
• Coal formation in many parts of the world, but
  needed to be swampy marshes with lots of rain
  near the equator

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The Evidence

• Fossil Evidence

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The Evidence

• Fossil Evidence

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Sequence of Rock Types

• The Rock Record
• Rocks in Argentina identical to ones in Africa
• Diamond rich rocks in South Africa match rocks in
  Brazil
• Coal beds in NA, Britain, and Belgium same
• Red sandstone same in NA, Greenland, Britain,
  Norway

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The Evidence

• Mountain Ranges

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Ancient Climates

• Tropical plant remains (coal deposits) found in
  Antarctica
• Glaciation in Africa, South America, India, and
  Australia during the same time

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The Evidence

• Climatic Evidence
• Glacial evidence

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Theory of Continental Drift

• Vocabulary
• Continental shelf part of a continent that
  extends under shallow water from the oceans edge
  to the steeper sea floor slope.
• Pangaea- all land
• Panthalassa all seas
• Theory of Continental Drift continents were
  once one landmass that broke apart and moved to
  present locations.

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Evidence of Continental Drift

• 1.
• 2.
• 3.
• 4.

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Evidence of Continental Drift

• 1. Puzzle Pieces continents fit together like a
  giant puzzle esp. SA and Africa
• 2. Fossil Record the same plants, trees, and
  animals and coal beds occur in different
  continents
• 3. Rock Record same sequence of rock occurs on
  different continents, same mountain ranges occur
  on different continents
• 4. Climate same glaciation marks on different
  continents some now warm, fossil indicate
  tropical climates where now cold.

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Pangaea
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