Landforms

• Ocean Ridge

  Found at constructive margins

  formed when diverging plates are underwater (Mid-Atlantic Ridge)

  Underwater volcanoes erupt along mid-ocean ridges and can build up above sea level (Iceland formed by build up of underwater volcanoes)
• Rift Valley

  Found at constructive margins

  Plates diverge beneath the land , the rising magma causes the continental crust to fracture forming fault lines

  As the plates keep moving apart the crust between the faults drops down to form a rift valley

  Volcanoes found near them (Mt. Kenya in East African Rift System)
• Fault Lines

  Formed at conservative plate

  2 Plates get locked together and pressure builds up causing the plates to jerk past each other which leads to earthquakes ( San Andreas Fault)
• Island Arcs

  Formed at destructive oceanic-oceanic plate margins

  A cluster of islands that sit in a curved line which are formed when volcanic eruptions take place underwater ( Mariana Islands )
• Fold Mountains

  Formed at oceanic-continental plate margins

  Made up of sediments that have accumulated on the continental crust which are folded upwards along with the edge of the continental crust ( The Himalayas)
• Formation of Volcanoes away from plate margins

  1. Magma plumes are vertical columns of extra hot magma that rises from the mantle
  2. Volcanoes form above magma plumes
  3. the magma plume remains stationary over time but the crust moves above it
  4. Volcanic activity decreases as the crust moves away from the plume
  5. New Volcanoes form above plume as crust moves
  6. chain of volcanoes is formed ( Hawaii)
• How do volcanoes form at oceanic-oceanic destructive plate margins ?

  The denser oceanic crust is subducted forming a deep sea trench which triggers earthquakes and volcanic eruptions
• How are earthquakes formed at continental-continental destructive plate margins ?

  Two plates of continental crust move towards each other , neither one is subducted so there aren't any volcanoes but the build up of pressure causes earthquakes
• How are volcanoes formed at oceanic-continental destructive plate margins ?

  Magma is less dense than the continental crust above and will rise back to the surface to form volcanoes

  AS one plate moves under the other they can get stuck which leads to a build up of pressure. When pressure becomes too high the plates jerk past each other causing earthquakes
• How do volcanoes forma at constructive plate margins ?

  Magma is less dense so it rises and can erupt to form a volcano

  Plates don't move in a uniform way which causes pressure to build up. Too much pressure causes plates to crack causing earthquakes