New Zealand’S Natural Landscapes


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PPT of NZ's natural landscapes

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New Zealand’S Natural Landscapes

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