Ice on the land GCSE AQA Geography

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  • Created on: 04-05-14 18:59
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Ice on the Land
Ice levels over time
The Earth has Glacial Periods and Interglacial Periods
1) The earth goes through cold periods which last for millions of years called ice ages. During
ice ages, large masses of ice cover parts of the earth's surface.
2) The last ice age was the Pleistocene that began around 2.6 million years ago.
3) During ice ages there are colder periods called glacial periods when the ice advances to
cover more of the earth's surface. Each one lasts for about 10000 years.
4) In between the glacial periods are warmer periods called interglacial periods when the ice
retreats to cover less of the earth's surface. Each one lasts around 10000 years.
5) The last glacial period began around 100000 years ago and ended around 10000 years
Ice covered much more of the earth's surface 20,000 years ago
1) Since the beginning of the Pleistocene there have been permanent ice sheets on
Greenland and Antarctica. Ice has also covered other parts of the world during the colder
glacial periods.
2) Ice covered a lot more of the land around 20,000 years ago (during the last glacial
periods) ­ over 30% of the earth's land surface was covered by ice including nearly all of
the UK.
3) At the moment we are in an interglacial period that began around 10,000 years ago.
Today about 10% of the earth's surface is covered by ice- the only ice sheets are the ones
on Greenland and Antarctica.
Evidence of changing temperature comes from three main sources
Chemical evidence- the chemical composition of ice and marine sediments change as
temperature changes, so they can be used to work out how global temperatures have changed in
the past
-Ice and sediments build up over thousands of years so samples taken at different depths show the
temperatures over thousands of years.
- The records show a pattern of increasing and decreasing temperatures, which caused the ice to
advance and retreat.

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Geological evidence- some landforms we see today were created by glaciers in the past. This
shows that some areas that aren't covered in ice today were covered in the past, which means
temperatures were lower.
Fossil evidence- the remains of some organisms are persevered when they die, creating fossils.
Fossils show the distribution of plants and animals that are adapted to warm or cold climates at
different times in the past. From this we can tell which areas were warmer or colder in the past.…read more

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Temperature changes throughout each year and over the years. Both of these things affect the
glacial budget:
1) Glaciers advance and retreat seasonally:
In the summer there's more Ablation than accumulation because more ice melts
when it's warm. This means there is more negative glacial budget so more glaciers
In the winter there is more accumulation than ablation as it is colder and the
snow and ice doesn't melt.…read more

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Corries begin as hollows containing a small glacier. As the ice moves by rotational slip, it
erodes the hollow into a steep-sided, armchair shape with a lip at the bottom end. When
the ice melts it can leave a small circular lake called a tarn or corrie lake.
A pyramidal peak is a pointed mountain peak with at least three sides. It's formed when
three or more back to back glaciers erode a mountain.…read more

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Lateral moraine is a long mound of material deposited where the sides of the glacier was.
2) Medial moraine is a long mound of material deposited in the centre of a valley where two
glaciers met (the two lateral moraines join together).
3) Terminal moraine builds up at the snout of the glacier when it remains stationary. It's
deposited as semicircular mounds.
4) Ground moraine is a thin layer of material deposited over a large area as a glacier melts.…read more

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There's only a short growing season (when there's enough light and warmth for plants to
grow) ­ so plants don't have much time to recover if they're damaged.
2) Decay is slow because it's so cold. This means any pollution or litter remains in the
environment for a long time.
Tourism has economic, social and environmental impacts
Economic impacts
1) Lots of new businesses are set up for the tourists, e.g. restaurants, hotels and guiding
companies for the sports activities. This boosts the local economy.…read more

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