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Plate Tectonics. Earth back then…. Earth Now. Pangea. World used to be a “super continent’ PANGEA. Proof of Pangea. Fossil Evidence – only a few places in the world Fossils – Remains of skeletons preserved in rock seen in multiple continents; walk or swim?. Proof of Pangea.

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Plate Tectonics


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pangea
Pangea
  • World used to be a “super continent’
    • PANGEA
proof of pangea
Proof of Pangea
  • Fossil Evidence – only a few places in the world
    • Fossils – Remains of skeletons preserved in rock seen in multiple continents; walk or swim?
proof of pangea6
Proof of Pangea
  • Glacier Evidence (from ice age)
    • Large valleys, scratches on rocks seen in multiple places
proof of pangea7
Proof of Pangea
  • Glacier Evidence – scratches on rocks
proof of pangea8
Proof of Pangea
  • Glacier Evidence – scratches in warm places….

Any better explanation?

theory of continental drift
Theory of Continental Drift
  • Alfred Wegner
    • Earths plates floated
    • Drifted apart over millions of years
recall the layers
Recall the layers….

Upper mantle + crust = ????

Lithosphere

  • Asthenosphere
    • - Fluid layer
theory of plate tectonics
Theory of Plate Tectonics
  • Land masses existed as plates that MOVE
theory of plate tectonics14
Theory of Plate Tectonics
  • How movement occurs
  • Convection currents
    • Heating
    • Some places hotter than others
      • Different materials heat differently
    • Difference causes pushing
thoery of plate tectonics
Thoery of Plate Tectonics
  • Plate boundaries & their interactions
evidence for plate tectonics
Evidence for Plate Tectonics
  • Pieces of earth move & some will collide
    • Earthquakes & volcanoes provide evidence
    • Earthquakes & volcanic eruptions occur at plate boundaries
plate boundaries interactions
Plate boundaries & interactions
  • 3 possibilities exist
    • Divergent Plate Boundaries
    • Convergent plate boundaries
    • Transform plate boundaries
plate boundaries interactions19
Plate boundaries & interactions
  • Divergent Plates
    • Plates move apart
  • Rising magma pushes crust
  • Old rock pushed farther away
  • New rock at spreading - Ridge (ocean) / Rift (land)
techniques to learn about earth volcanology
Techniques to learn about earth -Volcanology

Things to look for: Volcano types: Rift eruptions

  • Occurs at spreading ridges of mantle
    • Ocean or land
  • Easy flowing eruptions
  • Large amount of lava
slide23
http://www.seed.slb.com/en/scictr/watch/living_planet/mountains.htmhttp://www.seed.slb.com/en/scictr/watch/living_planet/mountains.htm
plate boundaries interactions24
Plate boundaries & interactions
  • 3 types of collisions:
    • Oceanic – continental
    • Oceanic – oceanic
    • Continental – continental
  • Convergent Plates
    • Plates move closer together
  • 2 types of rock
    • Oceanic - under water
    • Continental - above water
  • Possible combinations???
plate boundaries interactions25
Plate boundaries & interactions

Oceanic - Continental

  • Denser plate SUBDUCTS (slides under)
    • Oceanic (basalt) is denser = ALWAYS subducts below continental (granite)
  • Less dense plate rises
  • Subducted plate melts & magma is pushed up
  • Mountains & volcanoes created

Pushes up from subducted plate

plate boundaries interactions26
Plate boundaries & interactions
  • Denser plate SUBDUCTS (slides under)
    • Older = denser = subducts
  • NO uplift
  • Subducted plate melts
  • Chain of volcanoes form @ subduction site (island arc)

Plates are level

plate boundaries interactions28
Plate boundaries & interactions

Continental - Continental

  • NO subduction because of similar density
  • Crushing & crumbling of rocks
  • Mountain formation
plate boundaries interactions30
Plate boundaries & interactions
  • Transform plate boundaries
  • Sliding past each other
  • NO new land forms
  • Produce earthquakes