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Continental Drift

Continental Drift. In the beginning. The hypothesis that the continents once “fit” together has been around since the late 1500’s. Early mapmakers noticed the puzzle-like fit of continents such as Africa and S. America.

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Continental Drift

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  1. Continental Drift

  2. In the beginning • The hypothesis that the continents once “fit” together has been around since the late 1500’s. • Early mapmakers noticed the puzzle-like fit of continents such as Africa and S. America. • It was once thought that volcanic activity “spit” the continents apart (which was actually pretty close)

  3. Alfred Wegener • It wasn’t until 1912 that the first logical, reasonable, supported hypothesis was offered. • Alfred Wegener proposed that all the continents had once been joined and slowly drifted to their present-day location over the last 200 million years.

  4. Continental Drift • He called this hypothesis Continental Drift, proposing that the continents had all been joined at one time in a giant landmass called Pangaea (Greek for “all the earth”).

  5. While early hypothesis were based on a lot of circumstantial observations and weak evidence… • Wegener took it one step further and gathered six pretty strong pieces of evidence to support his ideas of giant landmasses and drifting continents Wegener in Greenland in 1930

  6. The “Evidence” • Piece number one… • The puzzle-like fit of the coastline (although this was obvious to early map-makers as well).

  7. The “Evidence” • Piece number two… • Wegener found similar animal fossils on separate continents. • He knew that the land reptile Lystrosaurus could not swim across the present-day Atlantic Ocean • He also knew that the Mesosaurus was a fresh-water crocodile-like creature that would not have swam across an ocean

  8. The “Evidence” • Piece number three… • Wegener found similar plant fossils on separate continents. • It was more logical to assume the areas were once connected that it was to assume the seeds were carried across the ocean by the wind.

  9. The “Evidence” • Piece number four… • Wegener found ancient climate evidence to support his idea. • Tropical plant fossils were found in areas that are now cold. • Evidence of water was found in deserts • Etc…

  10. The “Evidence” • Piece number five… • Rocks of similar age and type were found on either side of the Atlantic Ocean

  11. The “Evidence” • Piece number six… • Evidence From Glaciers (both glacial deposits and glacial scaring) was found in places too warm for glaciers today

  12. Disappointment for A. Wegener • Although there was strong evidence to support the theory of Continental Drift, there were a few unanswered questions. • 1. Wegener could not satisfactorily explain “WHAT” was causing the continents to move. • 2. No one could provide a good theory of “HOW” the continents were moving. “I know I am right about this drifting continents thing”

  13. The Verdict • Wegeners theory of Continental Drift was not accepted by the scientific community • He died in 1930, before further evidence could provide the “mechanism” that was moving the continents was found. • The Alfred Wegener Institute for Polar and Marine Research was founded in 1980 (at least he got that)

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