The restless Earth summary

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Restless Earth

  • Crust: outer layer of the earth
  • Plate: a section of the earth's crust
  • Plate Margin: the boundary where two plates meet 
  • Mantle: dense mostly solid layer between outer core and crust 
  • Convection Currents: the circular currents of heat in the mantle

Oceanic Crust:

  • Newer- most less than 200 million years old
  • Denser
  • Can sink
  • Can be renewed and destroyed

Continental Crust:

  • Older- most over 1500 million years old
  • Less dense
  • Cannot sink
  • Cannot be renewed or destroyed

Destructive plate margins: 

  • Convection currents in mantle cause plates move together
  • Denser oceanic crust sinks under continental crust (subduction)
  • Great pressure exerted and oceanic crust is destroyed to form magma
  • Two continental plates meet each other, collide rather than sinking beneath each other. The collision boundary is a different type of destructive margin. 
  • Severe earthquakes and violent volcanic eruptions

Constructive plate margins:

  • When plates move apart constructive plate boundary results 
  • Occurs under oceans; as plates move apart cracks form between plates and magma forces way into cracks and makes its way to


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