Presentation on theme: "Restless Continents continental drift: the hypothesis by Alfred Wegener that states that the continents once formed a single landmass, broke up, and drifted."— Presentation transcript:
1 Restless Continentscontinental drift: the hypothesis by Alfred Wegener that states that the continents once formed a single landmass, broke up, and drifted to their present locations.- many fossils & rocksare found only on certain parts of certain continents.
2 Restless Continents- the continents slowly drifted away from Pangaea, which was the super-continent that existed 245 million years ago. (same time as dinosaurs)
3 Restless Continentssea-floor spreading: the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies.
4 Restless Continents- the best evidence of sea-floor spreading comes from magnetic reversals recorded in the ocean floor.- iron in the newly formed rock at the mid-ocean ridges has a magnetic field that is slowly spreading across the sea floor & reversing the polarity.- this occurs once every 200,000 years
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