Edexcel B Restless Earth

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Tectonic Plates

The Earths Structure and tectonic movement

  • The earth’s core is 5000°c – these high temperatures are caused by radioactive decay
  • The heat given off by the earth’s core causes convection currents in the mantle and these convection currents drive plate motion
  • Inner and Outer core made up of iron and nickel
  • Mantle is semi-molten rock – more solid near the top
  • Crust is made up of tectonic plates – oceanic and continental  


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Magnetic Field

Magnetic Field

  • Protects us from harmful radiation and particles in the solar winds – they would destroy all living things and burn us
  • It also helps us navigate
  • The solar winds get destroyed by the magnetic field around the earth – it blocks the solar winds from reaching the earth
  • A reason for the magnetic field is because of the convection currents in the outer core – which is made by iron and nickel – these convection currents create electrical and magnetic fields
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Plate Boundaries

Constructive plate boundary

  • Plates get pulled away from each other – caused by convection currents moving in the opposite direction
  • When the plates move apart the magma spills out from underneath (lava is runny and not explosive)
  • When the lava cools it creates new land e.g. the Atlantic mid-ocean ridge
  • Causes shield volcanos 

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Plate Boundaries

Destructive plate boundary

  •  Ocean and ocean or Ocean and continental
  • One of the plates gets forced under – and the carbon in the crust gets heated and CO2 gets formed
  • The pressure, because the CO2 gas needs to escape builds up and causes an earthquake and composite volcano
  • The subduction zone is the area where the one plate gets forced underneath the other plate
  • Where the oceanic plate goes under there are ocean trenches 

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Plate Margins

Conservative Plate Margin

  • Two plates moving in different directions or the same direction but at different speeds passed each other
  • The plates get jammed as they move pass each other building up extreme tension
  • When they move pass each other it causes big earthquakes (San Andreas fault line)

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