Plate tectonics
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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

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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

  • Fossils match across oceans

  • Rock types and structures match across oceans

  • Ancient glacial features


Evidence


Evidence


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.


Earth’s Layers


The Plates


Types of Plate Boundaries

  • Convergent

    • Push together

  • Divergent

    • Pull apart

  • Transform

    • Slide past one

      another


Convergent Boundaries

  • Oceanic- Continental

    • Oceanic is denser and sinks below continental

    • Creates a subduction zone

    • Creates trenches, volcanic mountain arc


Mt. St. Helens, Washington


Convergent Boundaries

  • Oceanic- Oceanic

    • Oceanic being of equal densities both “sink”

    • Creates a subduction zone

    • Creates trenches, island arc


Japanese Islands- Island Arc


Convergent Boundaries

  • Continental- Continental

    • Continentals being of equal densities both “push up”

    • Creates folded mountains


Himalayas, Asia


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

  • Plates slide past each other

  • Creates earthquakes


San Andres Fault, CA


Animations

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


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