Section 2 Restless Continents

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Section 2 Restless Continents

• By Mrs. Smith

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Magnetic Reversals

• Magnetic reversals of earths magnetic polarity
  are recorded in the newly formed rock at the
  sites of sea floor spreading
• When the new molten rock cooled, it was
  magnetically coded

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Wegeners Theory of Continental Drift

• Alfred Wegener wrote his theory in the 1900s
• Continental drift is the theory that continents
  can drift apart from one another and have done so
  in the past
• This explains why fossil findings matched up on
  various continents
• Explains glacial grooves

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Continental Drift

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Pangaea

• A giant landmass that joined all of todays
  continents into one giant landmass
• Pangaea Greek for all earth
• Happened 245 million years ago

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Sea-Floor Spreading

• Mid-ocean ridges are places where sea floor
  spreading takes place
• New lithosphere is created as older materials are
  pulled away
• -when the sea floor spreads, magma rises and
  fills the space, creating new lithosphere

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Review

• List three clues that continental drift helps to
  explain.
• Why wasnt Wegeners theory of continental drift
  accepted at first?
• What does sea floor spreading have to do with
  magnetic polarities?