Ice on the Land

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  • Created by: Carolyn
  • Created on: 01-04-13 22:52
Pleistocene
The last ice age. It began around 2.6 million years ago and ended about 12,000 years ago when the Holocene began.
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Glacial
Cooler periods during ice ages when ice advances. Each one lasts for about 100,000 years. The last glacial period began around 100,000 years ago and ended about 10,000 years ago. Ice covered over 30% of the Earth's land surface - nearly al of the UK.
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Interglacial
Warmer periods between glacial periods when ice retreats. Each one lasts for around 10,000 years. We are currently in an interglacial period that begun 10,000 years ago, and today ice covers 10% of the Earth's land surface.
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Chemical evidence of changing temperature
The chemical compostion of ice and marine sediments change as temperature changes, so can be used work out how global temperature has changed. Ice and sediments build up so samples taken at different depths show the temperature overthousands of years
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Geological evidence of changing temperature
Some landforms were created by glaciers in the past. This shows that some areas were covered by ice in the past, which means temperatures were lower.
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Fossil evidence of changing temperature
The remains of some organisms are preserved. Fossils show the distribution of plants and animals that are adapted to warm or cold climates at different times. From this we know which areas were warmer or colder in the past.
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Glacier
Masses of ice that fill valleys and hollows, that move downhill under the force of gravity. Often extend from an ice cap or ice sheet like long tongues of ice.
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Accumulation
The input of snow and ice into the glacier. You get more of this than ablation in the upper part of a glacier so its called the zone of ...
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Ablation
The output of water from a glacier as the ice melts. You get more of this than accumulation in the lower part of the glacier so its called the zone of ...
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Glacial budget
The difference between total accumulation and total ablation for a year. Positive = larger glacier and snout advances down the valley, accumulation exceeds ablation.
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Plucking
Meltwater at the base, back or sides of a glacier freezes onto the rock. As the glacier moves forward it pulls pieces of rock with it.
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Abrasion
Bits of rock stuck in the ice grind against the rock below the glacier, wearing it away, like sandpaper.
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Rotational slip
At the top end of the glacier the ice moves in a circular motion. This can erode hollows in the landscape and deepen them into bowl shapes, like corries.
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Freeze-thaw weathering
Water gets into cracks in rocks then freezes and expands, putting pressure on the rock. The ice then thaws, releasing the pressure. If this process repeats it can make bits of rock fall off.
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Arete
A steep-sided ridge formed when two glaciers flow in parallel valleys. The glaciers erode the sides of the valleys, which sharpens the ridge between them. E.g. Striding Edge, Lake District.
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Pyramidal peak
A pointed mountain peak with at least three sides. It's formed when three or more back-to-back glaciers erode a mountain. E.g. Snowdon, Wales.
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Corrie
Begins as a hollow containing a small glacier. As the ice moves by rotational slip, it erodes the hollow into a steep-sided, armchair shape with a lip and steep back wall. When the ice melts a tarn is sometimes left. E.g. Red Tarn.
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Tarn
A small circular lake found in the bottom of a corrie. E.g. Red Tarn, Lake District.
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Truncated spurs
Cliff-like edges on the valley side formed when ridges of land (spurs) that stick out into the main valley are cut off as the glacier moves past.
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Hanging valleys
Valleys formed by smaller glaciers (called tributary glaciers) that flow into the main glacier. The glacial trough is eroded much more deeply by the larger glacier. so when the glaciers melt the valleys are left at a higher level.
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Ribbon lake
Long, thin lakes that form after a glacier retreats. They form in hollows where softer rock was eroded more than the surrounded hard rock. E.g. Windermere, Lake District.
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Glacial troughs
Steep-sided valleys with flat bottoms.They start off as a V-shaped river valley but change to a U-shape as the glacier erodes the sides and bottom, making it deeper and wider. E.g. Nant Ffrancon, Snowdonia.
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Holocene
The epoch we are in now.
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Ice sheet
An area of land covered by a minimum of 50,000km^2 of ice.
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Ice cap
A body of ice on land which is less than 50,000km^2.
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Weathering
The breaking down of rocks, soils and minerals through direct contact with the atmosphere.
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Erosion
The removal of weathered material via agents such as water, wind, or in this case ice.
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Other cards in this set

Card 2

Front

Cooler periods during ice ages when ice advances. Each one lasts for about 100,000 years. The last glacial period began around 100,000 years ago and ended about 10,000 years ago. Ice covered over 30% of the Earth's land surface - nearly al of the UK.

Back

Glacial

Card 3

Front

Warmer periods between glacial periods when ice retreats. Each one lasts for around 10,000 years. We are currently in an interglacial period that begun 10,000 years ago, and today ice covers 10% of the Earth's land surface.

Back

Preview of the back of card 3

Card 4

Front

The chemical compostion of ice and marine sediments change as temperature changes, so can be used work out how global temperature has changed. Ice and sediments build up so samples taken at different depths show the temperature overthousands of years

Back

Preview of the back of card 4

Card 5

Front

Some landforms were created by glaciers in the past. This shows that some areas were covered by ice in the past, which means temperatures were lower.

Back

Preview of the back of card 5
View more cards

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