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