ICE ON THE LAND
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- Created by: Sam
- Created on: 29-05-13 20:12
GLACIAL BUDGET
ZONE OF ACCUMULATION AND ZONE OF ABLATION
- Accumulation: input of snow and ice into the glacier
- Ablation: output of water as the ice melts
- More accumulation than ablation in the upper part - zone of accumulation
- More ablation than accumulation in the lower part - zone of ablation
GLACIAL BUDGET
- Difference between total accumulation and total ablation for one year
- Amount of ice in a glacier and whether it's advancing or retreating depends on it:
- Positive glacial budget - when accumulation exceeds ablation. Glacier gets larger and its snout advances down the valley
- Negative glacial budget - when ablation exceeds accumulation. Glacier gets smaller and its snout retreats up the valley
- When these are equal the glacier stays the same size and the position of the snout doesn't change
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GLACIAL BUDGET (2)
CHANGE IN THE GLACIAL BUDGET
- Glaciers advance and retreat seasonally
- More ablation in the summer - ice melts when it's warm, meaning a negative glacial budget and retreat
- More accumulation in the winter - more snowfall and less melting, meaning a positive glacial budget and advance
- Most glaciers have had a negative glacial budget since 1950 - earth's temperature has been increasing due to global warming
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GLACIAL EROSION
GLACIERS ERODE THE LANDSCAPE AS THEY MOVE
- Weight of ice in a glacier makes it move downhill, eroding the landscape in two ways:
- Plucking: when meltwater at the base, back or sides of a glacier freezes onto the rock - as the glacier moves forward it pulls pieces of rock out
- Abrasion: where bits of rock stuck in the ice grind against rock below the glacier,wearing it away
- At the top end ice moves in a circular motion called rotational slip - can erode hollows in the landscape and deepen them into bowl shapes
- Rock above glaciers is also weathered by conditions around glaciers - freeze-thaw weathering
GLACIAL EROSION PRODUCES SEVEN DIFFERENT LANDFORMS
- Arête: steep-sided ridge formed from two glaciers in parallel valleys - erode the sides of the valleys, sharpening the ridge between them
- Corries: begin as hollows containing a small glacier, eroded into a steep-sided armchair shape with a lip at the bottom end by rotational slip. Can leave a tarn
- Ribbon lakes: long, think lakes formed after glacier retreats - form in hollows where softer rock was eroded more than surroung harder rock
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GLACIAL EROSION (2)
- Pyramidal peak: pointed mountain peak with at least three sides, formed when three or more back-to-back glaciers erode a mountain
- Truncated spurs: cliff-like edges on the valley side formed when ridges of land that stick out are cut off as the glacier moves past
- Glacial trough: steep-sided valleys with flat bottoms - start off V-shaped river valleys but change to a U-shape as the glacier erodes sides and bottom, making it deeper and wider
- Hanging valleys: valleys formed by tributary glaciers that flow into the main glacier. Glacial trough is eroded much more deeply by the larger glacier so these valleys are left at a higher level
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GLACIAL TRANSPORT AND DEPOSITION
GLACIERS TRANSPORT AND DEPOSIT MATERIAL
- Can move material over very large distances - transportation
- Material's frozen in the glacier, carried on its surface or pushed in front of it - bulldozing when loose material is pushed in front
- When the ice carrying the material melts or the ice is overloaded it's dropped - deposition
- Rocks of all shapes and sizes are mixed up together
MORAINE
- Landforms made out of material dropped by a glacier as it melts
- Four different types depending on position:
- Lateral: long mound of material deposited where the side was
- Medial: long mound of material deposited in the centre of a valley where two glaciers meet
- Terminal: builds up at the snout when it remains stationary - deposited in semicircular mounds
- Ground: thin layer material deposited over a large area as a glacier melts
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GLACIAL TRANSPORT AND DEPOSITION (2)
DRUMLINS
- Elongated hills of glacial deposits - largest over 1000m long, 500m wide and 50m high
- Round, blunt and steep at the upstream end and tapered, pointed and gently sloping at the downstream end
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TOURISM ON ICE - CHAMONIX
WINTER SPORTS AND SIGHTSEEING
- Chamonix Valley is in eastern France at the foot of Mont Blanc, close to the border with Italy and Switzerland
- One of the most popular tourist destinations in the world - 5 million visitors a year
- Region has lots of glaciers including the Mer de Glace - longest glacier in France, 7km long, 200m deep
- Many other tourist attractions: 6 ski areas, 350km of hiking trails, 40km of mountain bike tracks, an Alpine museum and an exhibition centre
MANAGEMENT
- System of avalanche barriers maintained around the resorts, e.g. at Taconnaz
- Also avalanche awareness courses and daily bulletins to keep tourists aware of risks - less likely to be hurt or killed
- Amount of traffic managed by providing free public transport for tourists - amount of pollution reduced by using low emission buses
- Some hotels reducing energy use, e.g. by installing solar panels to heat water and systems to automatically turn lights off - reduced CO2 emissions
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FRAGILE ENVIRONMENTS
- Fragile environments are easily damaged and difficult to manage:
- Short growing season - not much time for damaged plants to recover
- Decay is slow because of cold - any pollution or litter remains in the environment for a long time
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