Landscapes in the UK: Glaciation 1. Extent of ice cover across the UK during the last ice age.

Transcription

1 Landscapes in the UK: Glaciation 1. Extent of ice cover across the UK during the last ice age. Key idea: Ice was a powerful force in shaping the landscape of the UK. In the past the climate has got colder and warmer. During cold times ice has covered the UK which did lots of things to our landscape. What is a glacial? A colder period in the Earth s history What is a glacial? A warmer period in the Earth s history. Today, are we in a glacial or interglacial? An interglacial. Which is why there is no ice covering the UK today. What is a glacier? A mass of ice moving slowly downhill due to gravity.

2 Landscapes in the UK: Glaciation 2. Processes: Weathering A) Weathering processes. What is weathering? The wearing way of rock in situ (in its original place). It is mostly caused by weather factors such as rainfall and changes in temperature. What is freeze thaw weathering? When water gets into cracks in the rock, if the temperature falls below zero, the water will freeze, expand by 9% and make the cracks bigger. In the day the water thaws again and the process repeats itself. Freeze thaw weathering in glaciated areas leads to bits of rock being broken off the valley side and being added to a glacier. Remember glaciers are not just made of ice, there are bits of rock in them as well.

3 Landscapes in the UK: Glaciation 2. Processes: Erosion B) Erosion. What is this? The wearing away and removal of rock, in this case by a glacier. 1. Abrasion: Rocks at the bottom of the glacier, scraping against the rock below, wearing it away. 2. Plucking: Glaciers freeze onto the rock below and then pull chunks of it off as they move downhill.

4 Landscapes in the UK: Glaciation 2. Processes: Transportation and movement: rotational slip and bulldozing C) Transportation: What is this? The carrying of material, in this case by a glacier. Two types of glacial movement: Rotational slip: This occurs when the ice moves in a circular motion. This process can help to erode hollows in the landscape, and deepen hollows into bowl shapes (corries) Bulldozing: Ice pushes material of all shapes and sizes as it moves slowly forward.

5 Landscapes in the UK: Glaciation 2. Processes: Deposition D) Deposition what is this? Occurs when material being carried by a glacier is dropped due to the glacier melting.

6 Landscapes in the UK: Glaciation 3. Characteristics and formation of landforms caused by glacial erosion: You need to be able to describe the characteristics of and explain the formation of the following glacial landforms: 1. Corries, aretes and pyramidal peaks 2. Glacial troughs, truncated spurs, ribbon lakes and hanging valleys. In order to explain the formation of a landform you need to do two things: 1. Give a full sequence what was needed for the landform to start to be created, then what happened, then what happened, then always say that this repeated over time leaving the landform in the landscape. 2. Name and explain the processes involved. You should also make sure you can draw a sequence of diagrams showing their formation and recognise photographs of the landforms and what they look like on an OS map.

7 What is a corrie? (Armchair shaped hollow in a mountain which may have a lake in it called a tarn. Explain the formation of a corrie. (4marks) As the climate gets colder, snow collects in small hollows on the side of a mountain. Layers of snow build up over time and eventually form a glacier. Freeze thaw weathering above the glacier adds pieces of rock to it. These pieces of rock then scrape along the mountain below the glacier by abrasion carving out a hollow. The glacier moves in a circular motion called rotational slip which widens and deepens the hollow into a corrie. When the climate warms again, the glacier melts leaving a hollow in the mountainside which may fill with water to form a lake called a tarn.

8 Armchair shaped hollow in the mountainside Steep back wall Tarn Rock lip at the front (When labelling with arrows. Make sure the arrow touches the feature you are labelling!)

9 What do corries look like on an OS map? Small circular lake indicates a corrie. This lake is called a tarn. Circular rock formation. Contours close together around the tarn shows steep back wall and sides.

10 Explain the formation of an arete/pyramidal peak. (4marks). First you would describe how a corrie is formed. Then finish the sequence either with What is an arete?. A sharp, knife-like ridge formed when 2 corries erode back to back. What is a pyramidal peak? Where several corries cut back to meet at a central point, the mountain takes the form of a steep pyramid. When two corries erode back to back, this creates a knife edge ridge in the landscape called an arete. When three or more corries erode back to back, this creates a sharp point at the top of a mountain called a pyramidal peak. To identify these on an OS map, just look for corries either back to back or 3 or more in a cluster back to back.

11 Glacial trough (U shaped valley) U shaped valley carved out by a glacier Ribbon lake: A long, narrow lake found in a glacial trough. Explain the formation of a glacial trough/ribbon lake. (4marks) Before glaciation, a river runs through the landscape through a V shaped valley. As the climate gets colder, a glacier forms in the valley by layers of snow building up then becoming compressed into ice. Pieces of rock are added to the glacier through freeze thaw weathering and plucking as the glacier pulls off pieces of rock as it advances. It then scrapes the pieces of rock along the valley bottom and sides, wearing them away into a U shaped valley. This is called abrasion. If part of the valley is made up of softer rock it will erode more deeply. After glaciation this may fill with water creating a long, thin lake.

12 Glacial trough Steep sides. Flat valley bottom. There may be a misfit stream running through the valley

13 (No contours on the valley floor as it is flat.) Stacks

14 Hanging Valley: A smaller valley perched high up on the side of the main valley. This may contain a waterfall. Explain the formation of a Hanging valley (4marks) This forms where a tributary valley flows into a main valley. It is too small to erode very much through abrasion so doesn t erode as deeply as the main glacial valley. When the climate warms up, both glaciers melt leaving the smaller tributary valley perched above the main one. There is often a waterfall where the two valleys join.

15

16 Truncated spurs: A former river valley spur which has been sliced off by a valley glacier, forming clifflike edges. Explain the formation of truncated spurs (4marks). Before glaciation when the climate was warmer, a river followed a winding path down a V shaped valley going around areas of harder rock, called interlocking spurs. As the climate got colder, a glacier filled the old river valley and eroded its way straight through the areas of rock that the river couldn t erode. The glacier cut off the interlocking spurs leaving cliff like edges called truncated spurs.

17

18 Landscapes in the UK: Glaciation 4. Characteristics and formation of landforms caused by deposition: You need to be able to describe the characteristics of and explain the formation of the following glacial landforms: 1. Erratics 2. Drumlins 3. Moraine In order to explain the formation of a landform you need to do two things: 1. Give a full sequence what was needed for the landform to start to be created, then what happened, then what happened, then always say that this repeated over time leaving the landform in the landscape. 2. Name and explain the processes involved. You should also make sure you can draw a sequence of diagrams showing their formation and recognise photographs of the landforms and what they look like on an OS map.

19 Erratics: What is an erratic? Rocks which have been transported and deposited by a glacier some distance from where they came from. Explain the formation of an erratic. (4marks) During glaciation, large chunks of rock can fall on to the glacier broken off by freeze thaw weathering (where water gets into crack in the rock, freezes and expands). These large rocks are then carried down the valley by the glacier. When the climate warms up the ice melts and can no longer carry the rock so it drops It in an areas with a different rock type. This is an erratic.

20 Drumlins: What are they? An oval hill made of glacial till. (material deposited by a glacier) Explain the formation of a drumlin. (4marks)

21

22 Drumlins on OS maps are lots of tiny rings of contours indicating small hills.

23 Moraine: Material carried aong and then deposited (dropped) by the glacier. Explain the formation of moraine. (4marks) Material is added to a glacier through freeze thaw and plucking. (where the glacier freezes onto rocks on the valley side and the pulls them off as it moves. ) This material is then carried along by the glacier as Lateral moraine (material at the side of the glacier) Medial moraine (material in the centre of the glacier formed when two glaciers and lateral moraines meet.) Terminal moraine (a pile of material at the furthest point of advance of the glacier.) When the climate warms, the glacier melts and can no longer carry the material so it drops it in ridges on the valley floor.

24 Landscapes in the UK: Glaciation 5. An example of a glaciated area in the UK to identify its major landforms of erosion and deposition: The Lake District. The Lake District is an area with many mountains and lakes in northern England. It was once covered by ice which created its landscape. Major landforms of erosion in the Lake District are found in the upland (high up) areas. There is a large corrie at Hellvellyn with a tarn called Red Tarn in it with aretes either side of the corrie where other corries have eroded back to back. These aretes are called Striding Edge and Swirral Edge. There are many glacial troughs throughout the Lake District with beautiful ribbon lakes (hence the name, the Lake District) Lake Coniston is a famous example of a ribbon lake in the Lake District. Landforms of deposition can be found in lower parts of the Lake District although many of them are hard to spot because they have been eroded by rivers or vegetation has grown over them. In Borrowdale, terminal moraines as used as boundaries to fields. Drumlin swarms can be seen at Swindale. Erratics can be found all over lower parts of the Lake District. Some may have been carried all the way from Scotland!!

25 Red Tarn with the arete Striding Edge on its side.

26 Coniston Water, an example of a ribbon lake in the Lake District

27 Erratics can be found all over the Lake District

28 A terminal moraine which now forms the boundary of a field at Borrowdale.

29 Landscapes in the UK: Glaciation Economic activities in glaciated upland areas Key idea: Glaciated upland areas provide opportunities for different economic activities, and management strategies can be used to reduce land use conflicts. What are the main economic activities in upland areas? Tourism Farming Forestry Quarrying It can be difficult to earn a living in upland glaciated areas because of the steep slopes, thin soils and problems with accessibility so these activities are extremely important to these areas.

30 Landscapes in the UK: Glaciation Economic activities in glaciated upland areas Tourism: Often the main source of income in the area as people want to see the mountains and lakes. Provides jobs. Example: Lake District see later notes. Farming: Poor soils in upland areas so mainly used for grazing sheep who tolerate the cold, wet and wind and poor vegetation. In valley bottoms, soils are thicker and machinery can be used on the flat land. Crops include cereals and potatoes.

31 Landscapes in the UK: Glaciation Economic activities in glaciated upland areas Forestry: Forestry is growing trees to then use for timber. Large areas of trees have been planted throughout Scotland and northern England. Conifer trees are well adapted to cope with the bad soils and steep slopes so this is a good way to use land that cannot be used for anything else. The timber is use in constructions and making paper. Quarrying: Quarrying is the digging out of rock from the ground. Upland areas are made of hard, resistant rock which is good for construction and road building. Example: Limestone taken from the Pennines is important in making cement. In lowland areas, sand and gravel which have been deposited by glaciers are also used to make concrete and cement.

32 Landscapes in the UK: Glaciation Conflicts between land uses A conflict is when two or more different groups of people have opposing views as to how the land should be used. Examples of land use conflicts in the Lake District: 1. Tourism and farming often come into conflict. Tourists may trample farmers fields and their dogs may scare the sheep. Often dry stone walls are damaged by tourists climbing over them which will upset farmers. Farmers may stop tourists going on to their land by putting up fences which tourists will be unhappy about. 2. Upland areas are a great place to put dams for HEP. This is good for local businesses and the government who require cheap, green energy sources, however, local people and farmers may have to be relocated to make space for the reservoir behind the dam.

33 Landscapes in the UK: Glaciation Conflicts between development and conservation Development is A country or area making progress in terms of wealth and improving quality of life. Conservation is Managing the environment in order to preserve, protect or restore it. Often these two aims come into conflict as activities that create jobs and opportunities often damage the environment. Examples: 2014 proposal for the Glenridding Zip Wire this would have been an important tourist attraction and brought tourists, money and jobs to the area. However, environmentalists and local people successfully argued that tourists would bring litter, footpath erosion and traffic congestion to the area. The scheme did not go ahead because of the possible impact on the environment.

34 Landscapes in the UK: Glaciation An example of a glaciated upland area used for tourism: The Lake District Attractions of the Lake District to tourism: Physical Attractions: (natural features that make people want to go there) Lakes such as Coniston water provide a location for water sports, cruises and fishing. Mountain landscapes such as the area around Hellvelyn attracts walkers and mountain bikers. Human attractions: Water sports and outdoor activities.. There is lots of culture. Beatrix Potters home called Hill Top now houses a museum. Scenic towns and villages such as Ambleside are enjoyed by tourists.

35 Landscapes in the UK: Glaciation An example of a glaciated upland area used for tourism: The Lake District Impacts of tourism in the Lake District: Economic impacts: 2014 tourists spent 1billion which supports hotels, shops and businesses. Thousands of jobs are available in these businesses. Traffic congestion on the small roads slows down business communication. Social Impacts: Negative impact on local people as tourists disturb local villages. Traffic congestion. 89% of tourists come by car. High house prices because of the demand for property as second homes. This makes housing unaffordable for local people. Jobs in tourism are mostly seasonal, poorly paid and unreliable which has an impact on people s quality of life.

36 Landscapes in the UK: Glaciation An example of a glaciated upland area used for tourism: The Lake District Impacts of tourism in the Lake District: Environmental impacts of tourism: Honeypot sites such as Cat Bells (a small hill that people like to climb) and Beatrix Potters House, Hill Top are showing signs of overcrowding with footpath erosion, litter and damage to grass verges by cars.. Air pollution and oil from vehicles and oil from boats can damage ecosystems. Walkers can damage farmland by trampling crops or leaving litter. Dogs can disturb sheep or cattle. Remember, if asked to discuss the impacts you can: Give positive and negative impacts. Give economic, social and environmental impacts.

37 Landscapes in the UK: Glaciation An example of a glaciated upland area used for tourism: The Lake District Managing tourism in the Lake District: How can traffic congestion be managed? There are many successful strategies in the Lake District. Several dual carriageways have been built around the Lake District to imprave access. Park and ride bus schemes such as the Hositer Rambler have been introduced to take people to honeypot sites in buses rather than all going separately in their cars. Speed bumps have been introduced in villages. Overall the use of public transport has been very successful however roads will be put under increasing pressure with increased visitor numbers into the future. How can footpath erosion be managed? The Upland Path Landscape Restoration project has successfully repaired paths, created steps, resurfaced paths with local stone and replanted native plants. Fix the Fells repair and maintain mountain paths supported by well funded organizations such as the national trust. The schemes have been very successful however, there are still hundreds of km in need of constant attention and their ongoing maintenance provides a huge challenge.

38 Landscapes in the UK: Glaciation An example of a glaciated upland area used for tourism: The Lake District As we have seen, managing environmental problems is fairly straightforward and has been successful, The problem of second homes in the Lake District forcing up house prices is much more difficult to address and is likely to remain an issue into the future.