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Describe the theory of continental drift. Did the Earth always look like this?

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Presentation on theme: "Describe the theory of continental drift. Did the Earth always look like this?"— Presentation transcript:

1 Describe the theory of continental drift. Did the Earth always look like this?

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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  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  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 Describe the theory of continental drift. 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? A. Deep-sea currents B. Earthquake formation C. Spreading of the sea floor D. Sedimentary rocks


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