GCSE Geography

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Author:
ghoran
ID:
137170
Filename:
GCSE Geography
Updated:
2012-02-25 08:31:09
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glaciation
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Description:
revision - Mr Parkes clues
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  1. what is a glacier
    a body of or mass of ice that moves
  2. abrasion
    rocks and rock fragments frozen into the bottom and sides of a glacier erode/wear away the rocks of the valley/land over which it moves
  3. plucking
    the tearing away of blocks/chunks of rock from the surface of the valley sides as the glacier moves over them
  4. how are plucking and abrasion interlinked
    plucking and abrasion are interlinked because plucking must occur before abrasion as plucking provides rocks for the glacier , and this allows glacial abrasion to occur as rocks in the valley scrape and scour the valley sides and floor
  5. what is a corrie
    a circular hollow , high on the a mountianside , surrounded by steep rocky walls except for a rck lip on the open side
  6. how is a corrie formed
    A corrie collects in a hillside hollow , as more snow accumulates , it is compressed and the air is squeezed out forming a névé . other time this becomes glacial ice due to the added pressure of accumulation of snow . Erosional processes such as plucking and abrasion deepen the hollow along side with freeze-thaw weathering . even though the ice is trapped in the hollow and unable to move downhill , gravity encourages the ice to move . this is known as rotational slip , it causes material to be plucked off the steep back wall forming crevasses this material is then used for abrasion to futher deepen the hollow . this means that the front of the corrie is less eroded so a lip forms , when enebales the ice to leave the corrie forming a glacier
  7. A named example of a corrie is :
    red tarn corrie in helvellyn in the lake district
  8. what is a drumlin
    a low rounded hill made of boulder clay . It has a blunt steeper end and a sharp/pointy/tapered end . they tend to form together in groups or swarms .
  9. we think drumlins form when :
    • a glacier carrying lots of glacial till advances across a lowland area
    • the higher lowland temperatures cause the glacier to melt but not fully
    • it deposits some of the glacial till on the ground be manages to keep carrying some of it forwards
    • however , due to melting the glacier is now so weak so it does not need much to encourage more deposition
    • any obstacle in the glaciers path (e.g. rock outcrop) is sufficient enough to slow it down and weaken it even more
    • as the glacier pushes against the obstacle , the pressure causes the ice to melt even more and lots of deposition occurs
    • this creates the steep stoss slope of the drumlin
    • the few bits of remaining ice manages to flow around the obstacle , but it is now so weak that it deposits any remaining glacial till
    • this creates the long , narrow tail (the lee slope)
    • hence drumlins are egg-shaped , i.e.thier upvalley ends are blunt and thier downvalley ends are tapered (leats deposition)
    • drumlin swarms show the direction the ice was flowing in (the direction of the drumlins long axes)
  10. a named example of a drumlin swarm is
    clew bay in Ireland
  11. draw and label a sketch of a drumlin
  12. what is calving and when is it likely to happen
    glacier calving is the breaking off chunks of ice into the sea . As glaciers flow towards the sea they often push over uneaven ground which creates cracks and forms crevasses (large , deep cracks) . when the glcaier reaches the sea , the ice breaks off at these crevasses as there is no land to support the weight of the ice . This is how icebergs are created .
  13. defien glacial budget/ mass balance
    the overall gain or loss of snow and ice by a glacier each year i.e. the difference between accumulation and ablation
  14. define zone of ablation
    an area towards the top of the mountianside , where the amount of snow that falls during the year is greter than the amount that melts . this is where glaciers form and then start to advance down the mountianside
  15. zone of ablation
    an area much further down the mountianside where the amount of snow that melts during that year is greater than the amount that falls . this is where glaciers melt and so start retreat back up the mountianside
  16. name the features a , b ,c , d ,e , f and h on the diagram
    • a = corrie
    • b = hanging valley
    • c = pyramidal peak
    • d = arrete
    • e = truncated spurs
    • f = u shaped valley
    • h = drumlins
  17. On the diagram below showing an alpine glaciated region, identify the arete, cirque, fiord, hanging valley, horn, truncated spurs, and U-Shaped glacial trough.
    2 = fiord

    what other features does a glacial trough often have
    • 1= u shaped glacial trough
    • 3=arrete
    • 4= pyramidal peak
    • 5= corrie
    • 6 = truncated spurs
    • 7= hanging valley
    • tarn
    • misfit stream
    • ribbon lake
    • a glacial trough also has steep sides and a wide flat floor
  18. what makes a glacier advance
    the accumulation of snow
  19. what is a ribbon lake and how does it form
    A ribbon lake is a large, narrow lake occupying a u-shaped valley. They form after a glacier retreats . they form in hollows where abrasion and plucking was more able to erode the rock as the rock was less resitant softer rock than the surrounding hard rock
  20. a named example of a ribbon lake is
    Windemere in the lake district
  21. when the ice melts inside a .... it can leave a small .... lake called a .... a named example is ..... ....in the lake district
    • corrie
    • circular
    • tarn
    • red tarn
  22. an example of a glacial trough is
    Nant Ffrancon , Snowdonia
  23. how are hanging valleys formed
    Along its journey down the valley a glacier would be joined by tributary glaciers.These smaller tributary glaciers contained much less ice and so were less powerful. They could not erode their valleys as deeply as the main glacier so, where they met, the tributary valley was left “hanging” above the main valley.
  24. an example of a hanging valley is
    Oesmite falls in Yosemite valley in Calafornia
  25. what is a pyramidal peak and how do they form
    a pyramidal peak is a 3 or more sided slab of rock making a pointy shaped mountian . they are formed by the erosion of corries , the erosional processes forming pyramidal peaks include : abrasion , plucking and rotational slip . At least 3 corries containing glaciers form back to back and erode deeper and deeper in the landscape until just the central bit of the rock is remaining , which sticks up around the remaing land forming a pyramidal peak
  26. a named example of a pyramidal peak is
    Helvellyn in the lake district
  27. what are truncates spurs and how are they formed
    these are cliff like edges on the valley side . they are formed when rodges of land (spurs) that stick out into the main valley are cut off as the glacier moves past
  28. what is an erratic an how are they formed
    they are rocks and boulders carried by the ice and deposited in a totally different area of rock .
  29. an example of an erratic is
    Big Rock in Okotoks Alberta
  30. the largest drumlins can be over
    • 1000 metres long
    • 500 metres wide
    • and 50 metres high
  31. glacial troughs are .... ... valleys with .... ... they start off as a .... river valley but change to a ..... as the galcier erodes the .... and .... by ..... and ..... making it .... and ....
    • steep sided
    • flat bottoms
    • v shaped
    • u shaped
    • sides
    • bottom
    • plucking
    • abrasion
    • wider
    • deeper
  32. what are striations
    deep groves in surface rocks , made by the sharp edges of rock fragments carried in the bottom/sides of glaciers

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