Ice On The Land

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  • Created by: Georgie'
  • Created on: 25-03-16 16:26
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  • Ice On The Land
    • Landforms resulting from erosion
      • Ribbon Lake
        • Long, thin lakes that form after a glacier retreats.
          • They form in hollows where the softer rock was eroded more that the surrounding her rock
    • Landforms resulting from transportation
      • Drumlin
        • Elongated hills of glacial deposits- the largest ones can be over 1000m long, 500m wide and 50m high
        • They are round, blunt and steep at the upstream end and tapered,pointed and gently sloping at the downstream end
        • Found in Ribbon Valley, Lancashire
      • Moraine
        • Lateral
          • long mound of material deposited where the side of the glacier was
        • Medial
          • ound of material deposited in the centre of a valley where two glaciers  meet (two lateral moraine join together)
        • Terminal
          • build up at snout of glacier and deposited as semicircular mounds
        • Ground
          • thin layer of material deposited over  a large surface area as a glacier melts
    • Processes of erosion
      • Abrasion
        • weight of the ice scores the valley floor an d sides using the angular material rock trapped beneath the ice
        • results in a smoothand often shiny rock surface
        • scratches caused by large rocks beneath the ice can often be seen -striations
      • Plucking
        • when meltwater beneath the glacier freezes bonds the glacier base to the rocky surface below.
        • The process leaves behind a jagged rocky surface
    • Freeze-Thaw weathering
      • 1) water gets into cracks rocks
      • 2)     The water freezer and expands, putting pressure on the rock
      • 3)         The ice then thaws, releasing the pressure
      • 5)          it produces angular rock fragments
      • 4) Process repeats and bits of rock break off
    • Processes of movement transportation
      • Rotational slip
        • slippage of ice along a curved surface
      • Bulldozing
        • The pushing of deposited sediment at the snout by the glacier as it advances
      • Deposition
        • when the ice carrying the material (such as rocks and earth) melts the material is dropped on the valley floor
        • occurs when the ice is overloaded with material
    • Pleistocene
      • last ice age
      • it was a thick ice sheet that acted as a mirror and reflected heat this means the cooling effect was more visible
      • ice covered 30% of the earths surfaced spread south
        • Birmingham was a mile and a half under ice
      • During ice ages there are cooler periods called glacial periods
        • when the ice advances to cover more of earths surface. each one lasts 100,000 years
      • in between the glacial periods are warmer periods called interglacial periods
        • when the ice retreatscover less of earths surface. lasts around 10,000 years
      • evidence of changing temperature
        • chemical
          • chemical composition of ice and marine sediments changes temperatures changes
            • can be used to work out how  GLOBAL TEMPERATURES has changed in the past
          • ice and sediment build up over thousands of years
            • samples taken at different depths show show temps over thousands of years
          • the records show a pattern of increasing and decreasing temps, which caused ice to advance and retreat
        • Geological
          • same landforms created by glaciersin the past
            • This shows that some areas that aren't covered in ice today were covered in ice in the past this means temps were lower
      • present extent of ice coverage
        • about 10% of earths surfaces covered by ice
        • the only ice sheets are the ones in Greenland and Antartica
    • Impacts of glacial retreat
      • Environmental
        • increase in natural hazards- flooding, rockslide and avalanches- destroy habitats/ disrupt food chains
        • meltwater contributes to rising sea level- destroy costal habitats by causing flooding
        • Harmful pollutants can be trapped in glacier ice - rapid melting releases them back into environment polluting rivers and lakes
      • Social
        • water supply to some settlements reduced
        • Disruption toe power supplies from HEP leave some people with unreliable power supply
        • if businesses shut down local people will have to more away to find work
        • ice no longer available for recreational use for locals e.g. ice climbing
      • unreliable snowfall means that there might not be enough snow for winter sports
  • Case Study for a retreating glacier: Rhône
    • Background
      • in swiss alps
      • 7.8kn long
      • been retreating since 19th century
    • Evidence of retreating
      • Pictures
        • two pictures taken of the glacier in 1900 and 2008 show the different size and position of the glacier
      • Monitoring Data
        • The length of the glacier has been measured since 1879 and since then there has been a decrease in length
      • Amount of meltwater
        • As glacier retreats it produces more meltwater. Meltwater has formed a new lake infront of the glacier which has been increasing in size- glacier has been melting more rapidly
    • Cause
      • Global Warming
        • melts the snout of the glacier which causes it to retreat

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