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Cause of Plate Motions

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17.4 Cause of Plate Motions Mantle Earth s interior between the crust and the core Large-scale motion is believed to be the mechanism that drives the movement of ... – PowerPoint PPT presentation

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Title: Cause of Plate Motions


1
17.4
  • Cause of Plate Motions

2
Mantle
  • Earths interior between the crust and the core
  • Large-scale motion is believed to be the
    mechanism that drives the movement of tectonic
    plates

3
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4
Convection
  • Transfer of thermal energy by the movement of
    heated material from one place to another
  • Ex. Boiling water
  • Heat comes from radioactivity within the mantle

5
Convection Currents
  • Cycle of warm water rising and cool water sinking
  • The cooling of matter causes it to contract
    slightly and increase in density
  • then it sinks due to gravity
  • Warmed matter is then displaced and forced to rise

6
Convection Currents
  • Develop in the mantle
  • Move the crust and outermost part of the mantle
  • Transfer thermal energy from Earths interior to
    its exterior

7
  • Rising material spreads out, lifts and splits
    lithosphere at divergent boundaries
  • Downward movement pulls convergent boundaries

8
Ridge push
  • Tectonic process associated with convection
    currents
  • Occurs when the weight of an elevated ridge
    pushes an oceanic plate toward a subduction zone

9
Slab pull
  • Tectonic process associated with convection
    currents in Earths mantle
  • Occurs as the weight of the subducting plate
    pulls the trailing lithosphere into a subduction
    zone.

10
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