Ice on the Land

Ice on the Land

Ice Levels Over Time
1. Earth goes through cold periods - ice ages.
2. Last ice age was the Pleistocene, began 2.6 million years ago.
3. Glacial periods - when ice advances to cover more of Earths surface.
4. Pleistocene has left permanent ice sheets on Greenland & Antarctica.
5. Last ice age 30% of world was covered in ice.
6. We currently in a interglacial period.
7. Chemical Evidence - chemical composition of ice & marine sediments, used to work put how global temperature has changed.
8. Geological Evidence - Some landforms we see today are created from past glaciers , showing that some areas were covered in ice.
9. Fossil Evidence - remains of some preserved organisms, showing how the plants & animals adapted to the climate
Glacial Budget
1. Accumulation - input of snow & ice into glacier.
2. Ablation - output of water from glacier as ice melts.
3. More accumulation than ablation in upper part - so its called: zone of accumulation.
4. More ablation than accumulation in lower part - so its called: zone ablation.
5. Difference between accumulation & ablation is the Glacial Budget.
  1. Positive Glacial Budget - accumulation exceeds ablation. Glacier gets larger snout (the bottom of glacier) advances down valley.
  2. Negative Glacial Budget - ablation exceeds accumulation, Glacier gets smaller, snout retreats up the valley.
  3. If there is the same accumulation & ablation over a year, glacier stays the same size & snout doesn't move.
6. Glaciers advance & retreat seasonally - summer; will retreat - winter; it will advance.
7. CASE STUDY: The Langgletscher Glacier
  1. In SW Switzerland
  2. Current length just under 7km
  3. Area is just over 10 sq km
  4. Since 1885 glacier has retreated around 675m
  5. advanced 3 times since monitoring:
    1. 1890s about 20m
    2. 1920-1930, 250m
    3. 1980s, 140m
Glacial Erosion
1. The weight of the ice & gravity - eroding landscape as it goes.
  1. Plucking - when meltwater freezes ono rocks and then freezes plucks the rocks out when glacier moves.
  2. Abrasion - bits of rock stuck in the ice grind against the rock below the glacier, grinding it away.
2. At the top of glacier, moves in circular motion (rotational slip) creating hollows and deepen bowls in the landscape.
3. Freeze-thaw weathering
  1. Water gets into cracks of rock
  2. Water freezes and expands cracking the rock
  3. Process repeated & rock can be broken off
4. Arete - steep sided ridge, two glaciers flow in parallel valleys, leaving a sharpened ridge in the middle.
5. Corries - created by the top of the glacier eroding a arm chair shaped hollow cause by rotational slip
6. Ribbon lakes - long thin lakes form after a glacier retreats - forms where the softer rock has eroded more.
7. Glacial Troughs - steep sided valleys with flat bottoms - start off as V-Shaped but change to U-Shaped from glacier erosion.
8. Hanging Valleys - formed by small glaciers (tributary glaciers) that flow into the main glacier.
9. Truncated Spurs - Ridges that would of originally gone over the mountainous area have been cut off and eroded by the glacier.
Glacial Transport & Deposition
1. Glaciers can move material over very large distance - transportation
2. Bulldozing - when the ice pushed loose material to the front of the glacier.
3. Deposition - when the ice carrying the material melts and the material is the dropped.
4. Moraines
  1. landforms made out of the material dropped by the glacier.
  2. Lateral Moraine- is a long mound of material deposited to the side of glacier.
  3. Medial Moraine - is a long mound of material deposited in the centre of the glacier (where 2 glaciers meet)
  4. Terminal Moraine - builds up at the snout of glacier deposited in semicircular mounds.
  5. Ground Moraine - thin layer of material from where the glacier has melted.
5. Drumlins
  1. are elongated hills of glacial deposits - can be over 1000 m long & 500m wide & 50m high.
  2. They're round, blunt & steep. gently sloping.
Impacts & Management of Tourism on Ice
1. Economic Impacts
  1. Lots of new business, e.g. restaurants.
  2. New business leads to new jobs.
2. Social Impacts
  1. Increased numbers of people & business mean the infrastructure, becomes congested.
  2. More jo opportunities for jobs so people don't have to leave to the city for jobs.
  3. Tourists could cause avalanches by skiing.
3. Environmental Impacts
  1. Fragile environment damaged people trampling on the snow & soil.
  2. Increased noise & pollution & litter from all the people & litter.
4. CASE STUDY: Chamonix,France
  1. In France
  2. Residence population is 10,000
  3. 100,000 visitors a day in summer
  4. 60,000 visitors a day in winter
  5. Over 350km of marked hiking trails,
  6. 40km of mountain biking tracks
  7. Numerous of cable cars,
  8. Economic Impacts
    1. Employment has risen for locals
    2. Increased tax revenue from local services.
    3. Money has to be spent maintaining footpaths
  9. Social Impacts
    1. Chamonix maintained as a safe & clean town
    2. Conflict between locals & tourists.
  10. Chamonix promotes responsible tourism.
  11. Tomorrow's Valley Initiative.
  12. Free public transport.
  13. Initiative called Escape Mont-Blanc (transport issues)
Impacts of Glacial Retreat
1. Economic Impacts
  1. Once glacier completely melted , amount of metlwater decreases.
    1. Means industries who supple meltwater will make less money & shut down.
2. Social Impacts
  1. Water supply to some settlements reduced.
  2. Disruption to power supplies (hydroelectric power)
3. Environmental Impacts
  1. Glacial retreat linked to increase in natural hazards
  2. Meltwater from retreating glaciers links to rising sea level.

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	Criado por zakbarwell mais de 12 anos atrás