AQA A Revision Guide – Ice on the Land

1. What does the term ‘Ice Age’ mean?

A period of time when ice sheets are found

on continents. We still have glaciers on land

today, so strictly speaking we are still in an

Ice Age.

2. How long has the recent Ice Age

lasted?

Scientists believe that the climate has been

similar for the last 2 millions years or so. This

is called the Pleistocene Era. During that

time, the glaciers have advanced and retreated and in doing so has created many impressive landscapes. In fact,

Britain would have looked like Greenland in the past. The maximum extent of the ice is shown on the map above.

3. Are special names given for the periods for when

glaciers advance and retreat?

Yes. Warmer periods are called interglacial periods and colder

periods are called glacial periods. During the most extreme

glacial periods during the Pleistocene, Britain was almost

completely covered by a huge ice sheet. The map on the left

shows this.

4. How do we know the climate has done this?

Glacial landforms found in places like Scotland and the Lake

District = ice must have been there (glacial period).

Similarly, fossil evidence of animals/ plants found in warmer

climates proves that there have been warmer periods

(interglacial period). For example, dig down in Trafalgar Square in London and you found skeletons of Rhino and

Lion. These sediments are dated at just 100,000 years before present (BP).

Another way is to analyse ice core evidence in places such as Greenland. Have you seen the ‘Day After Tomorrow’

film? At the start they were drilling for ice cores. Each year, a new layer of ice is created (a bit like the rings on a

tree), which means that you can drill down and look back in time. Crucially, air bubbles are trapped in the ice and if

you can get to them you can analyse the chemical composition and infer what the climate was like.

5. How is a glacier created?

When snow accumulates, the weight of the snow compresses the air out of the

snow below and this causes snow to turn into a firn. After about 20 years this air

is completely eradicated and the firn turns into a glacial ice. Think of what

happens when you make a snow ball! When you compact the snow together it

becomes denser and becomes more ice-like. Ice that is resting on slopes will

move due to gravity - when the ice begins to move it is called a glacier.

6. Are there different types of glacier?

Yes. A valley glacier is like a river of ice. It flows from high areas and follows the easiest route down – often in pre-

existing river valleys. An ice sheet is a huge mass of ice that covers a vast area - e.g. Greenland or Antarctica. These

account for 96% of ice on Earth.

7. Glaciers move: how does this happen?

Glaciers move due to gravity. However the

rate of movement is due to the GLACIAL

BUDGET. This is the difference between

the accumulation and ablation of ice each

year. The diagram (left) explains it:

Glaciers have an accumulation (adding

more) zone at the top, where it is coldest.

However, as the glacier moves downhill the

temperature increases and the ice will

melt. This is called ablation (melting).

The balance of the accumulation and the

ablation will determine whether a glacier

moves forward (advance) or move

backwards (retreat) – i.e. as suggested by

the glacial budget.

8. What example should you use for a glacier that is

changing?

The Mer de Glace (Sea of Ice) in the French Alps- the largest

glacier in France; 7km long and 200 metres deep.

It flows from Mont Blanc towards Chamonix.

It has been getting shorter and thinner since 1850. Advance in

the 1970s and 1980s by about 150 metres has given way to

retreat. It is retreating by about 30 metres a year (500 metres

shorter than in 1994).

Examine the pictures below; 1893 and 2008.

We know the Mer de Glace is retreating through photographic evidence, but also through 19th Century paintings.

Aerial imagery, old maps and debris left by the glacier all provide evidence of previous positions. The Mer de Glace is

retreating due to climate change. Temperatures are 1⁰C higher than 100 years ago, and 3⁰C higher above 1,800

metres. Combined with drier winters (i.e. less snowfall) the glaciers are melting away.

9. What about other changes to glaciers?

Glaciers change on a seasonal basis too; they tend to

advance in the winter and retreat in the summer.

Therefore, when trying to assess whether a glacier is

in a state of advance or retreat, you really should

compare position from Winter to Winter or Summer

to Summer!

10. How does a glacier shape the land?

There are three main erosion processes; Bulldozing,

Abrasion and Plucking.

Plucking is where a glacier moves over an area of

rock. Due to friction, the glacier melts and water

seeps into crack around the rocks below. The water refreezes and the rock

effectively becomes part of the glacier and is ripped out when the glacier

continues to move forward.

Abrasion is where rocks at the bottom of the glacier act like sandpaper –

grinding over the bedrock. This can polish the rocks or create sharp grooves

called striations.

Bulldozing is where rocks that are in front of the glacier are physically

removed by the advancing glacier.

11. Where does weathering fit into this?

Weathering is the break down of rock in situ (i.e. no movement) by the process

of the weather. The glaciers do not have anything to do with this process! The

diagram on the right shows this process.

However, the rocks that are shattered from the rock faces in this way can then be used for abrasion or bulldozed

away by the glacier.

12. Landform created by erosion 1: Corries (called Cirques in France and Cwms in Wales)

Often found in North facing slopes. Snow doesn’t melt in the

summer and a glacier forms.

Plucking and freeze-thaw weathering remove rocks from the

backwall making them very steep.

Abrasion occurs at the base when the glacier starts to move

(rotational slip due to the weight) – rocks fed by freeze-thaw

weathering helps this (Bergschrund crevasse allows rocks to fall

through the glacier).

Less erosion takes place at the front of the corrie (less weight), so

a rock lip is formed (moraine can also build up here). When the

ice has gone this feature acts as a dam for a tarn to form.

13. Landform created by erosion 2: Arête

An arête is a sharp ridge cut when two corries either side of a mountain cut back to back.

The back/ side wall of each corries is attacked by freeze-thaw weathering and plucking

leaving a sharp ridge between them.

The picture on the left is Striding Edge in the Lake District.

14. Landform created by erosion 3: Pyramidal Peak

When you have three or more corries surrounding a mountainside, they cut back and

produce this feature. The diagrams below summarise arête and pyramidal peak formation.

15. Landforms created by erosion 4: Glacial Trough, Truncated Spurs and Hanging Valleys

Glacial Trough: due to abrasion, plucking and

bulldozing, the glacier will erode the landscape as

it moves downhill. Glaciers tend to occupy a

former river valley and the erosion turn s the

V=shaped cross section into a U-shaped one.

Truncated Spurs: River valleys have ‘Interlocking spurs’

(pictured right) like the teeth in a zip that overlap. However, a

glacier removes them and makes the valley straight. You can

see the pictured in the diagram above.

Hanging Valleys: If you understand how a glacial trough is formed, then these are quite easy to understand. The

main glacier is the most powerful at eroding the landscape and cuts down quicker than the smaller valley

glaciers that feed into it. Therefore, once the ice has melted away, you are left with a main trough with small

troughs feeding into the main valley. However, the smaller troughs are

way above the main valley as a result of their weaker erosive force.

Waterfalls are often found cascading from the hanging valley into the main

valley (see picture on the left).

16. Landform created by erosion 5: Ribbon Lake

Ribbon Lakes are formed when a glacier moves down a valley and moves

over an area of softer rock. This rock is eroded (abrasion/plucking) far

more easily than the surrounded rock and the valley is over-deepened at

this point. When the glacier retreats the hollow left becomes filled with

water and a ribbon lake is formed. These are long and narrow and occupy the U-shaped valleys – e.g. Lake

Windermere in the Lake District. Ribbon lakes can also be formed by deposition too. When a terminal/

recessional moraine is left by a glacier, this can act like a

dam and trap the water behind to form a lake.

17. How do Glaciers transport material?

Freeze-thaw supplies rock that fall onto the glacier.

Glaciers can also bulldoze rocks in front of it.

18. Why does a glacier deposit material?

When a glacier melts it can lose energy. Any material that is carried can therefore become deposited. Material

that is carried/ deposited by a glacier is called moraine. Depending on the amount of weathering/ erosion that

has taken place on the material this will determine its size. Small, fine sediment is called rock flour, slightly larger

sediment is called boulder clay or till. Large boulders dumped away from their source are called erratics.

19. What depositional landforms are created by glaciers?

Moraines are left by a glacier.

Ground moraine is the layer

left under the glacier. Lateral

moraine is found along both

edges of the glacier; it is the

weathered rock that has fallen

from the valley sides. When

these melt, ridges are left at the

side of the valley. Medial

moraine is where two glaciers

have joined together to form a

larger glacier. The lateral

moraine of the two glaciers will

be in the middle as a result.

When the glacier melts a ridge

will be found along the middle

of the valley. Terminal moraine

is dropped at the end of the

glacier at its snout. This can be

used to show the maximum

extent that the glacier reached.

Moraines are shown on the diagram above, but also drumlins are too – these are discussed on the next page.

Drumlins are formed when glaciers shape the

moraine on the valley floor into small hills. They have

a blunt end and a tapered end. They are found in

swarms and the landscape is described as having a

‘basket of eggs topography’ (see Hellifield in the

Yorkshire Dales on the left).

20. How can you identify glacial features on maps?

The contours give it away. Look back at your exercise books for more information on this.

Corrie with

tarn

Pyramidal

Peak

Arête

Ribbon Lake in

Glacial Trough

Truncated

Spur (it

would have

gone to

other side of

the valley)

Practice your map references and

direction/ distances too!

21. How can glaciated regions be used by people?

The first thing to draw your attention to is that in the revision guide

section about human uses of Fold Mountains (Restless Earth section) is

exactly the same as here. The Alps is your case study for both.

However, we will focus on specific named places and tourism in this

section.

22. What case study can be used for Winter Sports in Glacial

regions?

La Plagne. 120 million visitors go to the Alps each year for winter sports

such as bobsleigh, skiing, snowboarding, rock/ice climbing etc. La Plagne has tapped into this market.

When: Built in 1960s

Where: French Alps, 2000 metres up

Why: To make money from tourism! It was a good location as the height guarantees snow from December to

April (i.e. long season) and a glacier (Bellecote) which can guarantee skiing, even in the summer.

What other positives does La Plagne possess?: Large selection of bars, restaurant and nightclubs. Variety of

slopes for all abilities. Ski to doorstep. Not just skiing – other winter sports available.

Recent developments: Great access (train, 4 airports nearby and access to motorway network) made it very

popular. It now has six villages all interlinked by a quality lift system. It has even been linked up to Les Arcs to

produce a huge ski area. Expansion was done ‘in-keeping’ with the environment: buildings built in a traditional

style, rather than just building ugly tower blocks.

23. What case study for all year round tourism? Mer de

Glace, Chamonix

Chamonix has Europe’s highest mountain – Mont Blanc. It has a

permanent population of 10,000, but this can swell to 100,000 in

winter (snow sports) and 130,000 in summer.

The reason people go in the summer is the beautiful countryside,

hiking, walking, mountain biking, shops, restaurants and the Mer

de Glace. The Montenvers train takes people to the edge of the

glacier (pictured right). It was built in 1908. Once at the glacier, tourists can experience the ‘Ice Cave’ which has been

carved in the glacier.

24. What are the issues related to tourism in the Alps?

Economic Impacts Social Impacts Environmental Impacts

Thriving economy as a result of tourist spending

Tourism is all- year round. Demand for services is maintained throughout the year, creating jobs

Young people stay when they leave education – many job opportunities

Traditional way of life changed – decline in local crafts and skills

Large amounts of water needed for the resorts for drinking/ snow making

Noise from machinery scares wildlife

Forest cleared for slopes- soil erosion and water cycle?

Skiing damages vegetation underneath

An increase in vehicles has led to air pollution – this is often trapped in the Alpine valleys. This damages trees

This has created conflict. Many welcome tourism, whereas others do not. Tourists may be in conflict with each other

if one group wants peace and quiet and the other wants the lively nightlife and sport activities. Conservationists do

not like the damage being done to the environment. Many local people want further development as they can make

more money.

25. How is tourism being managed? (CONTINUATION OF YOUR CASE STUDIES FROM EARLIER)

LA PLAGNE CHAMONIX – RESPONSIBLE TOURISM

New building built in traditional style (wood)

Underground parking – ski to hotel and limits pollution in the resort

Some of the villages are above the tree line, so tree cutting not an issue

Avalanche fences built for protection

Part of the Vanoise National Park- conservation a key focus

The council has developed a policy of ‘integrated tourism’, which educates and involves visitors and local people in the protection of the Alpine environment. It:

Free public transport (reduce car usage)

Encourage local farming

Education about the Mer de Glace

26. What are Avalanches?

An avalanche is a rapid flow of snow down a slope. It can be a natural event of caused by human activities.

27. How are avalanches created?

Heavy snowfall

Rise in temperature – weakens the upper layers of snow

Wind direction – can build up snow on one side of the mountain. This overhangs on

one side and can become loose

Slope angle. Most avalanches occur on slopes between 30⁰ and 50⁰.

Type of slope – convex slopes are more prone to avalanches than concave slopes

However, humans can also cause them:

Off-piste skiing disturbs the slopes, as does walking and climbing

Removal of tress from slopes prevents the snow from being kept in one place too,

thus increasing the risk of avalanches

28. What are the effects of avalanches?

Loss of life – people buried and die of hypothermia if not found within minutes.

Injuries – broken bones and other serious injuries

Buildings buried/ destroyed

Roads blocked, which slows rescue efforts

29. What can the longer term effects of an avalanche be?

Small avalanches often cause little disruption. However, a major

avalanche can cause serious problems. Fear of a repeat incident can keep

the tourists away. The lack of facilities (destroyed) can also keep tourists

away. A loss of tourists can lead to the failure of businesses and

therefore loss of jobs can occur.

The avalanche at Montroc, near Chamonix, killed 12 in 1999 and

destroyed 20 houses.

30. What is happening to Europe’s glaciers? The Rhone Glacier in 1920 and 2005

They are retreating. As has been mentioned previously, temperatures have risen by 1⁰C

over the last century and has risen by 3⁰C over 1,800 metres in the last 40 years. The Mer

de Glace is 500 metres shroter than it was in 1994. Winter snowfall is unreliable and the

lower Alps is receiving less total snowfall overall. These will cause real problems for

glaciers.

31. What impact will the retreat of the glaciers have?

Economic Impacts Social Impacts Environmental Impacts

Some resorts will no longer be viable as Winter resorts- this is a real problem in the southern Alps. Fewer siightseers and ice climbers will be a problem in all resorts.

Less tourism will result in less income for the area

However, the big, high-altitude resorts, should prosper as people are forced to go to them. They have the facilities and amenities already and the ability to make artificial snow.

Agriculture could benefit from a higher snowline and warmer summers – a longer growing season.

Jobs could be lost if tourist numbers fall – higher unemployment

With no jobs, young people will leave to find work – change in the population structure

Services could decline, but the elderly that remain will demand more

The Alps is a ‘fragile environment’, whic h means it is easily damaged. A delicate balance exists, so the increase in temperatures/ loss of snow could mean that it is unihabitable for some species.

Less water, so river levels will drop that have their source in the Alps.

More avalanches

Flooding from melting glaciers

Rock falls as the ground thaws.

END OF SECTION