Ice on the Land Revision Guide Q6

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Question 6 Ice on the Land
The last Ice age
Pleistocene
18,000 years ago ice covered about 30 per cent of the land in the world. In Britain,
ice covered land as far as the Bristol Channel. During the last ice age the temperature
remained below 0°C which allowed the ice to remain on the land all year.
The last ice age was between 10 000and 2,000,000 years ago.
The temperatures went up and down, a shift, fluctuated.
18,000 yers ago there was 4 ice sheets that existed in the northern hemisphere.
There alternate were periods of glacial - cooling ice expands
and I nterglacial - warming- ice retreats during the last ice age.
The current ice coverage
It has retreated to both poles, therefore the level of ice is less
Greenland is only the major Ice Sheet in the northern hemisphere
The other Ice Sheet is Antarctica
Largest ice sheet is in Antarctica, this covers an area of 14million km² and holds 90%
of all fresh water on the earth's surface.
In places it is 2-3 kilometres thick
Ice is also on the mountain tops-Himalayas, Rockies, Andes in glaciers.
The colder it gets the further the ice will go
A glacier
A mass of ice that moves very slowly downhill.
They are found at high altitude across the globe, in upland areas.
The formation of glaciers and the process by which they shape the landscape around
them is called glaciation.
Always on the move
How we can learn about the past
Core samples
The deeper down the ice you get- the older it is
That ice will store air bubbles-some of them air pockets could be at least 1000
years old
They can measure the amount of CO2 and other gases trapped in the pockets
The less CO2 the colder it is and vice versa
They also look for dust-more dust, less vegetation so therefore should've been
colder.
Landforms
Direct evidence of glacial/erosion-tells you how far south the ice has gone -e.g erratics,
moraine, drumlins, boulder clay.

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Fossils
Identify plants and animals that lived in colder/warmer climates to find out how
climate changed over time.
Glaciers
Glacial Budgets
Glacial budget
-the balance between the inputs (accumulation) and the outputs
(ablation) of a glacier.
Positive budget means it is advancing
Negative budget means that it is retreating.
Accumulation -inputs to the glacier budget, such as snowfall and avalanches that
cause it to advance.
Ablation -outputs from the glacier budget, such as melting - melt water and
evaporation. Usually during Spring and Summer.…read more

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Plucking
A process of glacial erosion where individual rocks are plucked from the valley floor or
sides as water freezes them to the glacier.
It occurs when rocks and stones become frozen to the base or sides of the glacier and
are plucked from the ground or rock face as the glacier moves.
It leaves behind a jagged landscape.
Deposition
Most deposition occurs at the snout where most of the ice has melted.…read more

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Key Features
Steep back wall
Raised lip
Over-deepened hollow
Once ice has gone it leaves a Corrie lakeor tarnif precipitation is higher than
evaporation.
Arete
An arête is a knife-edge ridge.
It is formed when two neighbouring corries run back to back.
As each glacier erodes either side of the ridge, the edge becomes steeper and the
ridge becomes narrower.…read more

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If three or more corries have formed on a mountain the steep back walls are
together.
Forms a sharp point
They are steep
The aretes radiate outwards
Glacial Trough, Truncated Spurs, Hanging Valleys and Ribbon Lakes
Glacial Trough
Glaciers cut distinctive U-shaped valleys with a flat floor and steep sides.
The glacier widens, steepens, deepens and smoothes V-shaped river valleys, eg Great Langdale Valley in
the Lake District.
The images below show the difference between a U-shaped valley and a V-shaped valley.…read more

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Key facts
7Km long and 200metres deep
Forms NNW from MT Blanc towards Switzerland
Close to Charmonix an important ski resort
Since 1850 it has almost constantly retreated due to global warming.
Advanced briefly 1970-80'sdue to a change in weather patterns and sudden drops in
temperature 150metres
Can be explored by tourists and provides a valuable income.
Before refrigeration the ice was carved up and transported across France for the rich.
Is now retreating 30 metres a year due to climate change.…read more

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On melting the medial moraine forms a ridge down the centre of the valley
A ridge of sediment running down the centre of a glacier formed when two lateral
moraines merge
Medial moraines are found at the junction between two glaciers.…read more

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Formation of a drumlin
The shape of the drumlin indicates the direction in which the glacier was moving.
The drumlin would have been deposited when the glacier became overloaded with
sediment after it hit an obstacle.
The steep blunt end was formed when glacial material was deposited.
The glacier then moved over the drumlin forming the smooth tapered end.
It is An egg-shaped hill found on the floor of a glacial trough
E.g.…read more

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Impacts of glacial retreat on tourism:
Unreliable snowfall & retreating glaciers are impacting on the economies of such areas.
= less tourists
Snow not thick enough for skiing and businesses such as hotels may have to close
down.
Unemployment will increase in the area and younger generation may move away looking
for work.
Economic ­ industry relying on meltwater will suffer (e.g farming to irrigate); HEP.…read more

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Cause serious injuries Restaurants and hotels could be
destroyed or forced to close.
Buildings in the path could be
flattened or buried. If tourism declines businesses will
suffer and tour guides and instructors
risk unemployment.
Roads are often blocked slowing
rescue efforts
Businesses could close and force the
migration of younger people.
Climate Change in the Alps
Changes
Temperatures above 1800m have risen by 3 degrees in 400 years.…read more

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