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Intro
Objective 5 October 2012
Describe the theory of continental drift.
Did the Earth always look like this?
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.
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
Restless Continents
Pangaea All continents were once joined as a single, giant super-continent
Greek for “all Earth”
Existed 245 MYA
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)
Restless Continents
Magnetic Reversals
Proof of Sea-floor Spreading
Magnetic North and South poles switch positions
Recorded when molten rock solidifies
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.
Objective: 5 October 2012
Outro
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!