Geography GCSE - Glaciers

What was the extent of ice cover across the UK during the last ice age?

What are the Glacial processes?

• Freeze-thaw weathering

• Erosion - plucking & abrasion

• Movement & Transportation - rotational slip & bulldozing

• Deposition - why glaciers deposit sediment (till and out wash)

Freeze-thaw weathering

Plucking

1. Blocks of rock are pulled away by ice as it moves downhill

2. Melt water gets into crevices, freezes and pulls pieces of rock away

Abrasion

1. Sharp angular rocks are embedded in the ice (from plucking)

2. As ice moves rocks scratch & scrape against the surface of the valley

3. Larger boulders - serious damage to landscape (striations)

Relationship between plucking and abrasion

• Plucking first then abrasion

  —> The plucked rocks are the ones used in abrasion

• More plucking = more rocks & boulders embedded in ice so increased rate of abrasion

Bulldozing

Bulldozing is when the glacier destroys everything in its path when it is moving

How does the glacier move (basal sliding)

1. Weight of ice increases pressure at the base of the glacier

2. This increases warmth at the base of the glacier

3. This in turn increases melting meaning melt water is present

4. This melt water provides lubrication allowing the glacier to slide over the surface

5. Gravity causes the movement to be downhill

6. This is known as basal sliding

Rotational slip

1. Snowflakes collect in a hollow in the valley

2. More snow falls —> more snow is compressed

3. Air is squeezed out of the hollow so the snow becomes firn

4. With pressure of more layers of snow (over a thousand years) firn will become glacier ice

5. The glacier ice is trapped in hollow - unable to move but gravity encourages it to move

6. It moves out of the hollow in a circular motion called rotational slip

How can glaciers carry material?

1. Above glacier/on surface - F.T.W. causes block of rock to become detached/fall onto the ice from surrounding mountains

2. Inside - Rocks might fall into the glacier from F.T.W or buried in snowfall overtime

3. Beneath glacier - plucking has torn away rock from the base of the glacier

Glacial Outwash

Out wash is material (sand/gravel) that has been deposited by melt water streams in front & underneath a glacier

• Large material is deposited first as it is heavier and takes more energy to carry

• Fine material is deposited furthest from the glacier

• Sediment has been rounded & reduced in size by attrition because it is carried in water

• Sorted material

Glacial Till

Sediment is carried by ice and deposited in front of the glacier

• No attrition/abrasion has occurred because it was carried by ice

• So sediment is jagged and angular

• Sediment is not sorted (different sizes and shapes)

What is a corrie

A deep depression on a hillside with a steep back wall often containing a lake (‘armchair’ shape)

Names:

England & Scotland - Corries

Wales - Cwns

France - Cirques

Formation of a corrie

A. Beginning of glacial period

• Snow accumulates in a hollow, compressed into firn

B. During glacial period

• Rotational slip gouges out the hollow

  —> Plucking steepens the back wall

  —> Abrasion deepens the hollow

• F.T.W happens above the glacier

C.After glacial period

• Steep back wall (still F.T.W during winter)

• Corrie lake (tarn) - melted glacier

• Deep rock basin

• Scree

• Jagged summit (due to F.T.W)

• Rock lip

What are Aretes and how are they formed?

Arete is a sharp ridge of rock found between to corries

Formed when two corries are formed back to back

What is a Pyramidal Peak and how are they formed

A pyramidal peak is formed when three or more corries grow in hollows on all sides of a mountain.

As the corries erode the mountain behind them, the remaining rock is weathered into a sharp point.

What is a glacial trough (u-shaped valley)

A glacial trough is a valley with steep sides and a flat base, once occupied with a glacier

Formation of glacial trough (& truncated spurs & ribbon lakes)

Before glaciation:

• There is a v-shaped valley with a river through it

• The river meanders around interlocking spurs

During glaciation:

• Glacier forms in the v-shaped valley

• The glacier widens, deepens, steepens & straightens the valley by plucking and abrasion

After glaciation:

• After the glacier melts an over-deepened glacial trough/u-shaped valley remains

• It may be occupied by a ribbon lake/misfit stream

• It has a flat valley floor, steep valley sides and shoulders

• The interlocked spurs have become truncated spurs through erosion

What is a hanging valley

High-level tributary valleys from which there is a sharp fall to the level of the lower, main valley

Formation of a hanging valley (& ribbon lake)

Before glaciation:

• There is a v-shaped valley

• The main river in the v-shaped valley meanders around interlocking spurs

• There is a tributary valley in the side of the v-shaped valley

• A tributary river flows in the v-shaped valley which creates a confluence of main and tributary rivers

During glaciation:

• Ice occupies the valleys, widening, steepening, deepening & straightening them by plucking and abrasion

• There is a larger glacier in the main valley

• There is a smaller glacier in the tributary valley so less erosion occurs compared to the large valley

After glaciation:

• There is a main glacial trough/ u-shaped valley

  —> Steep valley sides with truncated spurs

  —> May be occupied by a misfit stream/ribbon lake

• Due to difference in erosion, tributary valley is left hanging above the main valley - hanging valley

  —>normally has a waterfall in it which connects to the misfit stream/ribbon lake

What are ribbon lakes

Long, narrow lakes on the floor of a glacial valley

What are misfit streams

Small streams in a large glaciated valley - are not in proportion with the size of the valley

Characteristics of drumlins

• Smooth hills

• 30-40 m high & 300-400 m long

• Blunt at one end tapered at another (egg-shaped)

Formation of Drumlins

1. Ice is pushing across a lowland area nut it’s overloaded and melting

2. The ice does not need much to encourage deposition; any small obstacle such as a rock outcrop or mound is sufficient

3. Most deposition occurs around the upstream end of the obstacle which forms the blunt end of the drumlin

4. The rest of the moraine that is deposited is then moulded into shape around the obstacle by the moving ice to form the tapered end downstream

What are erratics?

An erratic is a rock or boulder that differs from the surrounding rock and has been transported by ice over a long distance and deposited by a melting glacier.

What are the 4 types of morraine

Lateral, Medial, Ground, Terminal

What is lateral moraine

Lateral means towards the sides.

A lateral moraine is a ridge of material found along a U-shaped valley’s edge.

This material comes from freeze-thaw weathering along the sides of the valley causing shattered blocks of rock to fall onto the glacier below

The material is deposited on the valley floor as the glacier melts.

What is medial moraine

Medial means in the middle.

When two glaciers meet side-by-side, the lateral moraines join to form a ridge of rock.

When the ice melts, the material is deposited in the centre of a U-shaped valley.

What is ground moraine

Ground moraine is the material that is frozen to the glacier’s base

and gets stuck and deposited underneath the glacier on the valley floor

What is terminal moraine

Terminal means end.

This material is found at the glacier’s end or snout.

It is material that the glacier has bulldozed.

It is usually a large ridge of material (indicating the distance a glacier has travelled).

An example of an upland area in the UK affected by glaciation to identify its major landforms of erosion and deposition

The Lake District

Location:

North-west of England

Near the border between Scotland & England

What are some economic activities in upland glaciated areas

Forestry, Farming, Tourism & Quarrying

Forestry in upland glaciated areas

Benefits:

• Conifer trees are adapted to cope with the acidic soils (of U.G.A.)

• They utilise steep slopes

• Left to grow for 20-30 years before being felled

• Produce ‘soft’ wood for timber in construction industry/Making paper

Negatives:

• Has impacts on the environments

• Increases CO2 emissions

• Impacts animal habitats

Farming (Extensive agriculture) in upland glaciated areas

Benefits:

• Ideal for extensive agriculture e.g animal grazing

Negatives:

• Not ideal for farming

  —> Glaciers stripped away soil and vegetation

  —> Soils in these areas are thin and acidic

Tourism in upland glaciated areas

Benefits:

• Provide employment for thousands of people

• Can use area for outdoor activities - attracts tourists

• Increases economic activity - profits

Negatives:

• Can cause overcrowding leading to traffic congestion, litter etc.

  —> bad for environment

Quarrying in upland glaciated areas

Benefits:

• U.G.A.s made of hard resistant rock

  —> can be quarried to provide stone for construction industry & building roads

• Limestone in U.G.A - valuable resource used in chemical industry, conditioning soils, making cement

Negatives:

• Destroys natural landscape

• Noise pollution for locals & air pollution

• Destroys animals habitats

Conflict between land uses e.g. Conflict between locals and tourists

Problems:

1. Increased litter

2. Traffic congestion - roads busy

3. Footpath erosion - visual pollution

4. Noise & air pollution - visitor traffic

5. Services may close as second home owners are not permanent residents

   Solutions:

   1. Put more bins

   2. One-way systems, improved public transport

   3. Stone paths, signs to direct walkers to alternative routes

   4. Improve rail & bus services

   5. Advertisement of housing in the area

Conflict between development & conservation

Arguments for development & against conservation:

• More tourists will come

• Provides more jobs for locals

• Increases economic development

Arguments for conservation & against development:

• Development likely to drove away visitors who come for peace and tranquility

• Already huge range of activities

• Development ruins the valleu

• Need to conserve the natural beauty and heritage

• Conserve plants and animals

  —> Can also bring in tourists and retains the locals identity & culture

Attractions for tourists in the Lake District

Physical attractions:

• Lakes (Windermere/Ullswater) - water sports, cruises, fishing

• Mountain landscapes with peaks (Helvellyn, Scafell Pike) - walking mountain biking

• Adventure activities - abseiling, rock climbing etc.

Cultural/Historical:

• Landscape - inspired writes & poets (William Wordsworth)

• Beatrix Potter - lived close to lake Windermere, her home now a national trust attraction

• Scenic towns/villages (Ambleside/Grasmere)

• Monuments (Muncaster castle)

Social impacts of tourism in the Lake District

Good

• Lots of tourist - benefits local’s income so improves their quality of life

Bad

• Over 89% visitors arrive by car

  —> roads narrow & winding

  —> major issue of congestion

• House prices high

  —> 20% of property either in holiday rental/ second homes

• Jobs in tourism mostly seasonal

  —> poorly paid & unreliable

Economic impacts of tourism in the Lake District

Good

• Tourists spend a lot of money

  —> in 2014 spent £1000 million

  —> supports hotels, shops & restaurants

• Thousands of local people have work opportunities

  —> in shops, hotels & other services

  —> provides them income

• New businesses

  —> e.g adventure tourism

  —> provide jobs for local people

Bad

• Traffic congestion

  —> slows down business communications

Environmental impacts of tourism in the Lake District

Only Bad

• Main tourist (‘honeypot’) sites & footpaths show signs of overcrowding

  —> footpath erosion, litter, damage to verges by cars

• Pollution from vehicles & boats

  —> damage ecosystems

• Walkers can damage farmland by trampling crops/leaving litter

  —> Dogs can disturb sheep & cattle

What are the strategies used to manage the impact of tourism in the Lake District

Managing Traffic congestion:

• Several dual-carriageways built - improve access

• Transport hubs e.g. at Ambleside - help create an interchange between parking, buses, ferries walking & cycling

  —> helps to relieve congestion elsewhere

• Park and ride bus schemes e.g. ‘Honister Rambier’ have been expanded

• Traffic calming measures e.g speed bumps introduced in villages

Managing footpath erosion:

• The Upland Path Landscape Restoration Project

  —> successfully repaired & re-surfaced paths & created steps with local stone and re-planted native plants