Glaciers Geography GSCE

notes on glaciers for GCSE

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  • Created on: 04-06-11 17:40
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A large mass of ice which persists throughout the year, and moves slowly down slope in a liquid
manor by its own weight. Glaciers are formed in areas where the winter snow doesn't have a chance
to melt, and consecutive snowfalls accumulate and compress into ice.
The accumulation of ice
When snow falls it accumulates very quickly, but much of the thickness (90%) is due to the pockets of
air trapped between the snowflakes, rather than the snow itself. If temperatures remain cold
enough, more snow will cause the lower layers to be compressed and much of the air will be
removed. After one winter the snow will have formed a more compacted structure called firn or
neve. More snowfall weighs the neve down squeezing more air out. This process repeated over 20
to 30 years will firm glacial ice which is almost impermeable. Glacier ice forms in upland areas above
the snowline. This is because the input (accumulation of snow) exceeds the output (rate at which it
melts). This created a permanent cover of snow and ice.
Glaciers as systems
The glacier system operates as a system with inputs, processes and outputs.

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The main inputs are snowfall and sediments falling from the valley sides due to frost shattering and
other forms of weathering. The main outputs are evaporation and water from melted snow. Glacial
ice is stored in the system as well as transferred down the valley.
How do glaciers move?
Despite being solid and hard, glacial ice does flow. This happens in two ways:
1. When individual ice crystals slip across each other.
2.…read more

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Freeze thaw
Freeze thaw occurs in cold climates, freeze thaw happens when water expands and freezes, so when
it expands it gets bigger so the space that it is in puts pressure on the surrounding rock and the crack
widens. More often the temperature flocculates above and below freezing point the more effective
the frost shattering is at breaking off pieces of rock. When the crack widens this often makes the
rock fall down. Loose rocks are called scree.…read more

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Glacial troughs (Lauterbrunnen valley, Switzerland)
These are recognisable by their steep sides and a wide, flat valley floor.
The original valley was developed by a river
and any spurs that projected from the valley sides
have been cut back to become truncated spurs.
As the glacier develops in a river valley the
accumulation of ice results in a vast erosive
The glacier therefore deepens, straightens and widens the valley.
The upper slopes of the valley, lying above the glacier, are left intact.…read more

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After the glacier melts they form benches or Alps.
At the valley sides there can often be a large amount of scree as a result of weathering (frost
shattering) and mass movement on the upper slopes.
Corries/ cirques/ cwm (Glaslyn, Snowdonia)
These are semi-circular, steep side of a mountain or head of a valley.
The shape of the corrie is often compared to an armchair because of its steep back wall and
side walls and open front.…read more

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Rock fragments stick into the ice and scraped and eroded the sides of the mountain- a
processes known as abrasion.
The Glaslyn glacier also eroded into its base by plucking.
This occurred as melt water at the base of the glacier froze into the rocks.
As the glacier moves forward it dragged or "quarried" loose blocks from the corrie floor.
Eventually a deep crevasse, a bergshrund developed between the back wall of the cirque
and cirque glacier.…read more

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Pyramidal peaks/horns (the Matterhorn and the Eiger, Switzerland)
This is a jagged peak created by several corries/cirques eroding backwards. The
peaks become sharpened by frost action.
Hanging valleys
This is a tributary valley of a U shaped valley (glaciated valley), which ends abruptly high
above the floor of the U shaped valley and separated from it by an almost vertical slope-hence
locations of waterfalls.
They were formed because tributary glaciers were composed of a smaller depth of ice than
main glaciers.…read more

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An Frost shattering, Red tarn
amphitheatre-shaped abrasion, plucking and
depression in a rotational ice
mountain side, with a movement.
steep back wall and a
rock lip.
Arête Narrow, knife-edged Two cirques cut back Striding edge
ridge towards each other
Pyramidal peak Pointed peak with Three or more cirques The Matterhorn
radiating arêtes cut backwards.…read more

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Glaciers and ice sheets carry a huge amount of debris, ranging from boulders as big as houses to
the finest of rock particles. The rock waste is called moraine.
The debris comes from:
Glacial erosion
Rock falls- freeze thaw feeds the glacier with a continuous supply of rock fragments.
Rock avalanches occur, though less frequently, as a result of the undercutting of valley
Till/boulder clay
Eventually glaciers and ice sheets dump all the rock debris they carry.…read more

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