plate tectonics

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  1. Continental drift theory
    -made by Alfred Wegener

    -continents drifted apart
  2. evidence for continental drift
    -fit of s. america to africa

    -fossil evidence

    -rock structures

    -ancient climates
  3. (continental drift) Fitting continents
    -S. america to africa

    -edges on the continents fit perfectly prior to all the erosion
  4. (continental drift) Fossils
    Mesosaurus limited to S. Africa and E. America
  5. (continental drift) Rock types
    • -similar rock type in S. America and Africa
    • igneous rocks similar

    -mountain ranges are similar rock types
  6. (continental drift) Ancient climates
    • -pangea was centered over south pole
    • accounts for ext. glaciation in S. Hemisphere
  7. Pangea
    • one great continent composed of all continents got together at one point
    • they eventually broke up
  8. Reason against Continental drift
    -Transoceanic land bridges: how animals got from Africa to S. America

    Siberia and Alaska
  9. Seafloor spreading theory
    • -mid oceanic ridges show that the older layers go into the mantle.
    • new land comes out
  10. Evidence on seafloor spreading
    -measured magnetism in lava rocks

    -pattern of alternating striped of HI and LOW magnetism

    • -SFS carries old magma away from the ridge
    • new magma magnetized
  11. HI intensity
    normal polarity
  12. LOW Intensity
    reversed polarity
  13. Convergent boundaries
    -destructive margins

    -come together, one beneath the other

    -large earthquakes by subduction zone

    -mtn ranges form from collisions
  14. Divergent Boundaries
    -contructive margins

    -plates move apart, new seafloor created

    • -continental rifting
    • spreads landmasses
  15. Transform fault boundary
    -conservative margins

    -plates grind past one another

    -no subduction

    -no new crust formed

    -earthquakes are prone to happen near faults

    -provides transportation for the new crust formed at the ridges to the subduction zone
  16. Drives plate motion
    -convective mantle flow drives plate movement

    -plate subduction drives downward movement of convection

    -unequal distribution inside of Earth
Card Set
plate tectonics
plate tectonics
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