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Plate Tectonics. Spectra of Science Amole 2013. Continental Drift. Proposed by Alfred Wegener in 1915. Supercontinent Pangaea started to break up about 200 million years ago. Continents "drifted" to their present positions. Evidence. Some continents coastlines seem to “fit” together

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Plate tectonics

Plate Tectonics

Spectra of Science

Amole

2013


Continental drift
Continental Drift

  • Proposed by Alfred Wegener in 1915.

  • Supercontinent Pangaea started to break up

    about 200 million

    years ago.

  • Continents "drifted" to their present positions.


Evidence
Evidence

  • Some continents coastlines seem to “fit” together

  • Fossils match across oceans

  • Rock types and structures match across oceans

  • Ancient glacial features




Plate tectonics1
Plate Tectonics

  • In 1965, J. Wilson

  • Earth’s lithosphere is broken into sections called plates.

  • Plates are always shifting and moving.

  • Movement is driven by convection currents in the mantle.




Types of plate boundaries
Types of Plate Boundaries

  • Convergent

    • Push together

  • Divergent

    • Pull apart

  • Transform

    • Slide past one

      another


Convergent boundaries
Convergent Boundaries

  • Oceanic- Continental

    • Oceanic is denser and sinks below continental

    • Creates a subduction zone

    • Creates trenches, volcanic mountain arc



Convergent boundaries1
Convergent Boundaries

  • Oceanic- Oceanic

    • Oceanic being of equal densities both “sink”

    • Creates a subduction zone

    • Creates trenches, island arc



Convergent boundaries2
Convergent Boundaries

  • Continental- Continental

    • Continentals being of equal densities both “push up”

    • Creates folded mountains



Divergent boundaries
Divergent Boundaries

  • Plates move away from each other

  • Create gaps that new magma rises through making new crust

  • Cause of sea-floor spreading

  • Creates rift valleys and the Mid-Oceanic Ridge


Transform boundaries
Transform Boundaries

  • Plates slide past each other

  • Creates earthquakes



Animations
Animations

  • http://www.seed.slb.com/flash/science/features/earth/livingplanet/plate_boundaries/en/index.html?width=570&height=475&popup=true