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The Theory of Plate Tectonics: Continental Drift, Sea Floor Spreading, and Plate Boundaries

Explore the fascinating theories of continental drift, sea floor spreading, and plate tectonics. Learn about Alfred Wegener's hypothesis of continental drift, evidence supporting these theories, and the different types of plate boundaries.

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The Theory of Plate Tectonics: Continental Drift, Sea Floor Spreading, and Plate Boundaries

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  1. Chapter 7 Section 1: Continental Drift Section 2 : Sea Floor Spreading Section 3: Plate Tectonics

  2. Section 1 Continental Drift • Alfred Wegener • (1880-1930) • Proposed hypothesis of continental drift • Pangaea

  3. Evidence to support C.D. • Continents appear to fit together like a puzzle • Similar fossils have been found on different continents • Remains of warm climate plants in arctic zones and Arctic clues in tropical zones • Similar rock structures found on different continents

  4. Section 2: Seafloor Spreading • Magma below Oceanic crust pushes upward and outward forcing the crust into large underwater mountain ranges. • Mid Ocean Ridges

  5. new old Evidence for S.F.S • A theory • Has been proven to occur • Rocks increase in age as one moves away from the mid-ocean ridges. • Continents are measure farther apart by 1 or 2 inches per year

  6. Section 3: Theory of Plate Tectonics • Combines the hypothesis of continental drift with the theory of sea floor spreading. • Earth’s crust and upper mantle broken into plates. • Shift on layer of molten rock.

  7. Earth’s plates • Lithosphere • Earth’s crust and upper mantle • Layer that shifts • Asthenosphere • -like layer of mantle.

  8. Earth’s crust • Continental crust • Thick • Less dense • Older • Forms land • Oceanic crust • Thin • Dense • Younger • Forms ocean bottom

  9. Plate Boundaries • Divergent • Where 2 plates move apart • Sea floor spreading! • Mid-Atlantic ridge • Rift Valley

  10. Plate Boundaries contd. • Convergent Boundary • Where 2 plates move together. • Oceanic / Continental plate collision • Subduction zone. • Volcanic Mtns. • Trench

  11. Convergent Boundaries contd. • Continental / Continental crust collision • Forms mountains • India plate moving north / Eurasian plate moving south. • Himalayan Mountains

  12. Himalayan Mountains

  13. Oceanic/Oceanic convergent collision. • Creates a trench • Both subducted, but one more than the other

  14. Transform Boundaries • 2 plates sliding past each other • Strike-slip faults • Can move in different directions or the same direction at different rates. • San Andreas Fault in California. • Earthquake zone

  15. Transform Boundary

  16. Causes of Plate movement. • Convection Currents • The heating, rising, cooling, and falling cycle of molten rock in the earth’s mantle.

  17. Earth’s Plates and movement.

  18. Tectonic Plates and Land Forms.

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