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Continental Drift Theory: How the Earth's Continents Changed Over Time

Explore Alfred Wegener's Theory of Continental Drift, which explains how the continents were once joined together in the super-continent Pangaea and then drifted to their current positions. Learn about the evidence for continental drift, including the presence of the same fossils and rock types on opposite continents. Discover the process of sea-floor spreading and magnetic reversals that support this theory. Imagine how the Earth might look in the future if sea-floor spreading continues.

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Continental Drift Theory: How the Earth's Continents Changed Over Time

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  1. Objective 5 October 2012 Describe the theory of continental drift. Intro Did the Earth always look like this?

  2. Continental Drift

  3. Who? What? Where? When? • Alfred Wegener • Theory of Continental Drift • German scientist who developed the Theory of Continental Drift in 1912 • The theory that states that the continents once formed a single landmass, broke up, and drifted to their present locations.

  4. Restless Continents

  5. Restless Continents • Evidence of Continental Drift • Same fossils found on opposite continents • Same rock types found on opposite continents • Warm climate plant fossils on cold climate continents

  6. Restless Continents • Pangaea • All continents were once joined as a single, giant super-continent • Greek for “all Earth” • Existed 245 MYA

  7. Restless Continents

  8. Restless Continents • Sea-Floor spreading • The process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies • Occurs at mid-ocean ridges (underwater mountain chains)

  9. Restless Continents • Magnetic Reversals • Proof of Sea-floor Spreading • Magnetic North and South poles switch positions • Recorded when molten rock solidifies

  10. Restless Continents • Summary: Alfred Wegener developed continental drift hypothesis explaining that continents once formed Pangaea and then moved to their current positions. This occurs due to sea-floor spreading and that is proved by records of magnetic reversals solidified in new ocean rock.

  11. Objective: 5 October 2012 Describe the theory of continental drift. Outro If Sea-Floor Spreading continues, what will the Earth look like in another 250 MY? Describe it or draw a picture!

  12. Restless Continents • When scientists proposed the Theory of Continental Drift, there were many skeptics. Which discovery confirmed that the continents move on plates? • Deep-sea currents • Earthquake formation • Spreading of the sea floor • Sedimentary rocks

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