New Zealand’S Natural Landscapes

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PPT of NZ's natural landscapes

PPT of NZ's natural landscapes

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  • 1. New Zealand’s Natural Landscapes How we got what we have
  • 2. Outline
    • Relief and landforming processes
    • Plate Tectonics
    • Processes to produce landforms
      • Faulting
      • Folding
      • Volcanism
    • Landmodifying processes
      • Erosion
  • 3. Relief and landform processes
  • 4. Plate Tectonics
  • 5. Theory of Plate Tectonics
    • The surface of the earth is covered by crustal plates which collide or are pulled apart from one another (fig 1)
    • They are driven by convection currents (fig 2)
    Figure 1: Plate tectonics theory says the earth is made up of interlocking crustal plates Figure 2: Beneath the earth’s crust
  • 6. Plate margins – Where the action is!
    • Plate margins are where plates collide, move past, slide past or spread apart
    • There are three types of plate margin
      • Destructive plate margin
        • Fig 1
      • Constructive plate margin
        • Fig 2
      • Passive plate margin
        • Fig 3
    Figure 1: Destructive plate margin Figure 2: Constructive plate margin (sea floor spreading) Figure 3: Passive plate margin
  • 7. Destructive plate margins
    • Where plates move towards each other one is forced under the other, called subduction
    • The thinner oceanic plate is forced under the thicker continental plate
  • 8. Constructive plate margins
    • Where plates are moving apart sea-floor spreading occurs
    • The magma rises into the cracks between the plates, this causes mid-oceanic ridges
  • 9. Passive plate margin
    • Where the plates are moving past one another it is known as a conservative boundary
    • Crustal rock is neither destroyed nor created
  • 10. Tectonics of NZ
  • 11. Processes to produce landforms
  • 12. Faulting
    • Faulting is the movement of the crust along zones of weakness
      • Generally plate margins
    • As pressure builds old, brittle rocks break and move in blocks
    • The land shifts upwards, downwards or sideways
    • The southern Alps of NZ have been uplifted by faulting
  • 13. Folding
    • Folding is the process where sedimentary rock is pushed and squeezed as surrounding hard rock is moved by plate tectonics
    • The soft rock bends and twists
    • This creates more gentle landscapes
    • The North
    • Island hill
    • country has
    • been formed
    • by folding
  • 14. Volcanism
    • Subducting oceanic rock melts and then escapes to the surface through a weakness
    • Typical volcanic landforms are
      • lava or ash erupted from volcanoes
      • Calderas, lake Taupo
      • Thick deposits of ash, the Volcanic Plateau
      • Old lava cones, Auckland volcanic field
  • 15. Land modifying processes
  • 16. Erosion
    • Once land is formed other processes occur to change or modify the landform
    • This wearing down and transportation of the earth’s surface is known as erosion
    • This occurs by
      • Weathering
      • Transportation
      • Deposition
  • 17. Weathering
    • The breaking down and wearing away of the land by chemical processes
    • Some of the these processes are
      • Fluvial erosion
        • Erosion by running water
      • Glacial erosion
      • Periglacial erosion
        • Freeze thaw
      • Aeolian erosion
      • Coastal erosion
  • 18. Transportation
    • Once the material has been broken down by one of the chemical processes it is moved from that place
    • Some of the forms of transportation are
      • Fluvial
        • Running water
      • Glacial
      • Aeolian
      • Coastal
  • 19. Deposition
    • Once the material has been transported it is put somewhere else
    • This is known as deposition
      • It is deposited somewhere
    • Example
      • A river transports material downstream
      • Where the river is flowing fast it picks up a lot of material in its flow
      • As the speed of the river slows it can’t transport all the material anymore, its not moving fast enough to hold it
      • It then deposits that material