Geography - Glaciers Revision AQA

The Earth over time goes through cold periods which last for millions of years called ice ages.

During ice ages there are cooler periods called glacial periods when ice advances

In between these periods are warmer periods called interglacial periods when ice retreats

The last ice age was the Pleistocene around 2.6 million years ago which ended about 10,000 years ago

From this point to present day is called the Holocene

Therefore, there must have been a temperature change and there is evidence for this. Chemical evidence; Geological evidence; and Fossil evidence

Ice sheets are huge masses of ice that cover whole continents. Glaciers are masses of ice which fill valleys and hollows

Accumulation is the input of snow and ice into the glacier

Ablation is the output of water from the glacier as ice melts

You get more accumulation at the upper part of a glacier so its called the zone of accumulation

You get more ablation at the lower part of a glacier so its called the zone of ablation

Glacial Budget is the difference between the total accumulation and the total ablation

A positive budget means the accumulation is bigger than the ablation so the glacier advances

A negative budget means the ablation is bigger than the accumulation so the glacier retreats

Temperature affects the budget. In Summer, the budget will be negative as there will be a lot of ablation because of the melting water

In Winter, the budget will be positive as there will be more accumulation because of the increase in snowfall

The Rhone Glacier is in the Swiss Alps and has been retreating since the ice age

There is evidence of this. The evidence can be shown in Pictures; Monitoring Data; and the amount of melt water

Global Warming is thought to be the main cause of the glacial retreat

Plucking occurs when melt water of a glacier freezes onto the rock below it and when the glacier moves forwards, it pulls out fragments of the rock leaving the landscape jaggered

Abrasion occurs when bits of rock in the glacier scrape along the rock below it, acting like sandpaper, making it smooth

At the top end of a glacier, the ice does not move in a straight line and instead, moves in a circular motion called rotational slip. This can make and erode hollows deeper and deepen them into bowl shapes

Freeze-thaw weathering occurs when water gets into cracks of the rock above the glacier. The water freezes and expands, putting pressure on the rock. The ice then thaws, releasing the pressure. If repeated, bits of rock could fall off

Arete: A knife edged ridge formed between two side-by-side valleys. When the glacier erodes the sides of the valleys it sharpens the ridge

Corrie: Begin as hollows containing a small glacier. The ice moves by rotational slip and erodes the hollow into an armchair shape with a lip at the bottom. When the ice melts it can leave a tarn

Ribbon Lake: A long narrow lake that forms after a glacier retreat

Hanging Valley: Are formed by tributary glaciers that flow into the main glacier. The trough is eroded  by the larger glacier so when it melts the valleys are  left at a higher level. They are often marked with a waterfall

Pyramidal Peak: A sharp pointed mountain peak with at least three sides. Its formed when three or more back-to-back glaciers erode the mountain

Glacial Trough: A V-shaped valley eroded by a glacier to form a U-shaped valley which is more wide and steep sided

Truncated spurs: Are formed when ridges of land stick out and are cut off as the glacier moves past them forming a cliff-like edge on the valley side

Glaciers can move material over long distances. This is called transportation

The material is frozen in the glacier, carried on its surface or pushed in front of it. Bulldozing is when the material is pushed in front of the glacier

When the ice carrying the material melts, the material is dropped on the valley floor. This is called deposition

The dropped material makes landforms such as moraines and drumlins

Moraines:

• Lateral moraine - A path of deposited material running along the edge of the glacier
• Medial moraine - A path of deposited material running down the centre of a valley where two glaciers met
• Terminal moraine - Deposited material at the snout representing the maximum advance of the glacier

Drumlins: Are egg-shaped hills formed from glacial deposition

Areas covered in snow and ice attract lots of tourists but the environments are very fragile - there easily damaged and difficult to manage:

• There's a short growing season so plants don't have to much time to recover if damaged
• Decay is slow because it is cold. This means pollution or litter in the area will stay there for a long period of time

Economic:

• New business for tourists boosts the local economy

Social:

• Tourists can trigger avalanches on slopes which can cause injury or death

Environmental:

• Increase pollution and littler

 Management Strategies:

• Tourists kept informed on avalanche risks so they know were to avoid

The Chamonix valley is in the eastern France at the foot of Mont Blanc and contains many glaciers, however, tourism is a problem for the environment

Economic: 

• Companies make a lot of money from tourism e.g. a ski lift companie has a turnover of $50 million

Social:

• Tourist developments have increased the chances of avalanches which can lead to injury and death

Environmental:

• Masses of tourists can cause a lot of traffic which increases pollution levels e.g. a study from 2002-04 showed pollution was higher in Chamonix than it was in central Paris

Management Strategies:

• Traffic is managed by providing free transport which lowers pollution levels

Many areas are being affected by glacial retreat and unreliable snowfall:

• Retreat and unreliable snowfall means no ice and snow available for winter sports like ice climbing and skiing which will reduce the amount of tourists in the area
• Fewer Tourists means businesses will struggle and will loose money and could go out of business
• This would lead to an increased unemployment rate in the area

Economic:

• Melt water will decrease meaning industries that rely on it like Hydro electric power will make less money and could shut down

Social:

The ice will no longer be available for recreational use for tourists and locals

Environmental:

• Can cause flooding and avalanches which could damage some habitats and disrupt food chains

An avalanche is a sudden downhill movement of snow. It is a significant hazard to people living in, or visiting, glacial areas. A slab avalanche is the most dangerous form of movement. It can be caused by:

• Heavy snowfall
• Deforestation (for example because of new ski runs) making the slope less stable
• Steep slopes, as this helps to increase the speed of movement
• Vibrations (for example from an earthquake)
• Layering of snow - for instance where snow is already on the mountain and has turned into ice, and then fresh snow falls on top which can easily slide down
• The wind direction piling snow which can overhang a mountain