Causes of Plate Motions

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Causes of Plate Motions
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Convection Current

• Only in fluids
• Results from density changes

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Convection Currents in your Home
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Convection Currents in the Mantle
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Unanswered Questions

• Are mantle convections currents permanent
  features?
• Do they shift positions over geologic time?
• How does a convection current start?
• What causes it to stop?
• Is convection taking place only in the upper
  mantle?
• Cause/Effect Does downward convection cause a
  subduction zone, or does subduction cause a
  downward current?
• What causes an upward current to develop under a
  continent?