Plate margins

• Constructive - plates that move away from each other

  • Magma pushes to the crust from the mantle
  • As it breaks through the overlying crust it causes earthquakes
  • When the lava breaks through the volcano erupts
  • When the lava has cooled down it forms new land (construction)
• Destructive - plates that move towards each other

  • When 2 plates move towards each other meet the more dense one is subducted beneath the less dense
  • Friction causes earth quakes
  • As the plate moves downwards it melts
  • The molten rock breaks through to the surface to form composite volcanoes
• Conservative - plates that move past each other

  • As two plates move past each other friction between the plates causes earthquakes.
  • One moves past the other quicker than the other one
  • Stress gradually builds up over years
  • The more build up the higher the intensity of an earthquake when it is released.
• Convection currents

  1. The mantle is made of magma
  2. When the magma is near the outer core it heats up and therefore rises
  3. Whereas the magma that is near the crust it cools down and sinks
  4. This creates a convection current that are circular movements that cause tectonic plates to move in the crust
• Slab pull

  1. As two plates meet, the crust of one is subducted underneath the other
  2. This causes the crust to direct underground
  3. As the crust is subducted gravity pulls it down. When the mass is greater the speed increases the pull
  4. Then , the crust underground breaks off and creates suction which increases the speed of the other to fall.
• Ridge push

  1. Where the plates are pulling apart magma rises to the surface.
  2. The magma cools and forms a ridge between the two plates
  3. This ridge then pushes the plates apart