GCSE Geography

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Author:
ghoran
ID:
137569
Filename:
GCSE Geography
Updated:
2012-02-25 06:52:35
Tags:
glaciation
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Description:
revision
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  1. what is freeze thaw weathering
    water gets into cracks/joinst in rocks the freezes (at night or during the winter) it then thaws and expands by 9% . this puts pressure on the rest of the rock surrounding the cracks/joints and gradually weakens them appart
  2. define snow line
    the line on a mountian above which snow and ice remain all year without melting , even in the summer
  3. névé
    an area of snow (snowfield) which starts to build up in hollows just below the top of mountians and leads to the formation of ice as the snow gets compacted layer upon layer
  4. glacier snout
    the end or nose of a glacier , the bit of the glacier that reaches furthest down the mountian side
  5. what is a glacier
    a body or mass of ice that moves
  6. what is a valley glacier
    a moving body or mass of ice within a valley between mountians
  7. what is an ice sheet
    a moving body or mass of ice that covers the whole of the land surafce over a wide area , not just within a mountian valley
  8. an ice sheet in the sea is known as an :
    ice shelf
  9. when parts of the ice shelf break off they form :
    icebergs
  10. which type of glacier is considered to be more effective at erosion and why
    • valley glacier because
    • 1) they are confined in a valley , therfore it is forced to touch the floor and each side of the valley meaning there is more contact (so more erosion) between the ice and the rock
    • 2) valley glaciers move quicker and they have more power
    • 3) they tend to carry more fragments of broken-off rock in them which can be used to scrape away the valley floor and sides by abrasion
  11. which type of glacier erodes the biggest area and why
    ice sheets because they are much bigger than they spread out more than valley glaciers meaning they cover wider areas
  12. would a glacier find limestone or granite easier to erode and why
    limestone beacsue it is softer than granite and has lots of joints in it which are lines of weaknessses that can be more easily attacked by weathering and erosion
  13. what is the name of the earths most recent ice age and how much of the surface did it cover
    pleistocene ice age , covered 30% of the earths surface at its peak
  14. when did the pleistocene ice age begin and end
    • began 2 million years ago
    • ended 10,000 years ago
  15. how does freeze-thaw weathering help increase the amount of glacial erosion
    it weakens rocks and shatters pieces off to be used for abrasion
  16. what is a rock basin and why does it form
    it is a bowl shaped hollow in the ground where a glacier has moved ahead and eroded the land away . thr rock basin forms beacsue it used to have a relitavely soft rock in it so the glacier finds it easier to remove this (via plucking and abrasion) than the surrounding harder rocks . when the ice age finishes the basin fills up to form a ribbon lake
  17. what is a rock bar
    it is the harder rock on each side of a rock basin , sticking up as a barrier (or a bar) and helping keep the meltwater trapped inside the ribbon lake
  18. define boulder clay/ glacial till
    the name given to all materials deposited by a glacier
  19. moraine
    all materials transported by glaciers , either on top of the glacier or inside the glacier . this material is deposited on the valley floor when the glacier melts , leaving features made of moraine all over the floor
  20. lateral moriane
    a long line or pile or moraine along the sides of the valley glacier where it touches the valley
  21. medial moraine
    a long line or pile of moraine in the middle of a glacier , formed after 2 seperate valley glaciers join together to make one massive glacier
  22. terminal moraine
    a line or pile of moraine runbning across the valley floor from one side to another , running parallel to where the glaciers snout is/would have been . terminal moraine shows the furthest point a mountian managed to get before it began to retreat
  23. ground moraine
    as a glacier melts it leaves a trail of glacial till behind it which forms a hummocky surface of ground moraine
  24. the general name given to all materials deposited by a glacier is glacial till consists of
    boulders of different sizes . it is an unsorted mix of angular rocks . this means there are bothe large and small rocks with shgarp edges

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