The Restless Earth - Plate Boundaries

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  • Created by: Molly
  • Created on: 16-02-13 13:47
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  • The Restless Earth - Plate Boundaries
    • Types of Crust
      • Oceanic
        • newer - most less than 200 million years old
        • more dense - on av 3.0g/cm3
        • can sink
        • thinner - 5-9km
        • rock type = basalt
        • contains SiMa
        • can be renewed and destroyed
      • Continental
        • older - most over 1500 million years old
        • less dense - on av 2.7g/cm3
        • cannot sink
        • thicker - 30-70km
        • rock type = granite
        • contains SiAl
        • cannot be renewed or destroyed
    • Destructive Plate Boundaries
      • Continental-Oceanic
        • continental oceanic moving towards eachother
          • more dense oceanic plate subducts under continental
        • Landforms
          • ocean trenches
            • found at point of subduction
          • fold mountains
            • found on continental plate
            • continental plate buckles up
          • composite volcanoes
            • found in fold mountain range in linear patterns
            • steep slopes and narrow base
            • layers of thick, cool lava and ash
            • + secondary cones
            • eruptions are infrequent but violent
            • lava is acidic and thick
              • under pressure
        • Case Study
          • Nazca (O) >> << South-American (C)
            • fold mountain range  = Andes
            • ocean trench = Peru-Chilie Trench
        • lots of pressure - strong earthquakes
      • Collision
        • continental continental moving towards eachother
          • both buoyant and cannot be destroyed
            • crumple to form fold mountains
        • Landforms
          • crumple to form fold mountains
          • NO volcanoes
        • Case Study
          • Indian >> << Eurasian
            • fold mountain range = Himalayas
        • build up of pressure - strong earthquakes
    • Constructive Plate Boundary
      • oceanic oceanic moving away from eachother
        • creates fissure in Earth's surface
      • Landforms
        • transform faults
          • right angles to main plate boundary due to different speeds
        • shield volcanoes
          • gentle slopes and wide base
          • layers of runny, hot lava
          • lava is basic
            • limited pressure
          • eruptions are frequent and non-violent
      • Case Study
        • North American << >> Eurasian
          • Mid-Atlantic Ridge
      • lack of pressure - small earthquakes
    • Conservative / Transform Plate Boundary
      • two plates are either:
        • sliding past eachother is opposite directions
        • moving in the same (or slightly different) direction but at different speeds
      • nothing is destroyed or created so NO LANDFORMS
      • Case Study
        • Pacific Plate is moving faster than the North American plate (which is moving slightly towards the Pacific Plate)
          • transform fault = San Andreas Fault
      • lots of pressure and friction - strong earthquakes

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