Continental Drift

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Continental Drift
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Alfred Wegener

• In 1910, Alfred Wegener became curious about the
  continents. He formed a hypothesis that the
  continents had moved.

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• Wegeners hypothesis was that all continents had
  been joined together in a single landmass and
  have since moved apart.

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• He named this super continent Pangaea. This idea
  was known as Continental Drift.

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Evidence

• 1. Landforms
• Mountain ranges and other features on continents
  provided evidence. South America and Africa fit
  together like puzzle pieces. A mountain range in
  South America lined up with a mountain range in
  Africa. European coal fields matched up with ones
  in North America.

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• 2. Fossils
• A fossil is a trace of an organism preserved in
  rock. Fossils of the reptiles Mesosaurus and
  Lystrosaurus had been found in places now
  separated by oceans. Another example was the
  fern-like plant Glossopteris found in Antarctica,
  Africa, South America, Australia and India.

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Laurasia

• -included most of the landmasses that make up
  todays northern hemisphere.
• Gondwanaland
• - Southernmost supercontinent that was once part
  of Pangaea

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• 3. Climate
• Fossils of tropical plants were found in
  Antarctica.
• Glaciers once covered South Africa. Deep
  scratches from the glaciers were found on rocks.

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Rejection of Wegeners Hypothesis

• Wegener could not provide evidence for the forces
  that push or pull the continents. Many
  geologists in the 1900s thought the earth was
  slowly shrinking and cooling. Wegener disagreed
  with this proposal because mountains usually
  appear in narrow bands along the edge of
  continents

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New evidence today

• The Ring of Fire showing that the plates once
  were connected and seismic activity in the mantle
  has caused the movement and the eruption of
  volcanoes and earthquakes.

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