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2014 Revision Guide - Mountain Environments 1. What do we know about mountains? 1.1 Physical characteristics Altitude and gradient Elevation, volume, steepness, and spacing have been used as criteria for defining a mountain. Mountains cover 24% of the Earth's land mass. 10% of people live in mountainous regions. Most of the world's rivers are fed from mountain sources, and more than half of humanity depends on mountains for water Weather and climate Tall mountains have different climatic conditions at the top than at the base. Different elevations have different ecosystems At the highest elevations, trees cannot grow, and whatever life may be present will be of the alpine type. Below the tree line, you may find subalpine forests of needle leaf trees, which can withstand cold, dry conditions 1.2 Human factors Population density Mountains are sparsely populated regions (not many people live there) because of: Harsh weather Steep land – hard to farm Less Oxygen Economic activity Many mountains and mountain ranges throughout the world have been left in their natural state. Used for : Recreation – Tourism Logging Mining Sheep grazing. Mountains have little economic activity. People who live and work in mountains Like deserts, mountains are used by similar groups of people. Multinational mineral companies, indigenous groups and also tourists. Mineral companies are keen exploit the rich mineral reserves in mountains to make profits. Indigenous groups like the Aymara in the Andes often live in small communities as subsistence farmers. Tourism in mountain environments can offer governments a large source of foreign income and also provide employment opportunities. Although, just like desert environments, mountains can many pose many challenges for humans to overcome. 1.3 Cultural representations Mountains are often used in a range of cultural resources including films, photography, expedition accounts and poetry. Each of these different cultural resources will use mountain environments for their own particular purposes but all will aim to use the characteristics of mountain environments such as their natural landscape, climatic extremes or hazardous conditions to create particular ideas in the mind of the viewer. For example, there are many great poems about mountains the sublime majesty of mountains has inspired history’s best minds, proving William Blake’s (a famous British poet) quote, “Great things are done when men and mountains meet.” 2. Where are mountains found? 2.1 Distribution and examples You will need to be able to locate the following mountain ranges on a world map Rockies, Andes, Alps, Himalayas, Great Dividing Range, Pyrenees and Atlas. 2.2What is the relationship between plate boundaries and mountain ranges? As you can see from the map opposite, most of the planets mountain ranges are found close to the Earth’s plate boundaries. Collision plate boundaries and destructive plate boundaries all form mountains but are created by slightly different processes. Collision plate boundaries Each year rivers wash tonnes of sediment into the sea. The sediments collect at the bottom of the ocean in depressions called geosynclines and are compressed into layers of sedimentary rock such as limestone and sandstone. At a collision plate boundary the plates move towards each other forcing the layers of rock up in a series of folds. This movement of plates can also cause earthquakes. Examples of a mountain range formed in this way is the Alps and the Himalaya Destructive plate boundaries At destructive plate boundaries, oceanic plates meet continental plates. The denser oceanic plate is pushed beneath the lighter continental crust, this movement is known as subduction. This causes the lighter continental crust to crumple upwards creating mountain ranges. The Andes are an example of a mountain range created in this way. The friction between the two plates can also cause earthquakes and as the oceanic crust is destroyed the molten rock forces its way through cracks in the crust to create volcanoes. 3. What are mountain climates like? There are three main factors which can affect mountain climates. These are altitude, relief, and aspect. 3.1 The altitude in a mountain environment can have a significant impact on temperature as temperatures will decrease with height. This is because the atmosphere is much better at trapping heat at sea level. 3.2 The relief, or the shape of the land can also impact on the amount of rainfall in mountain environments. Where there is one prevailing wind direction, on the windward side of mountain ranges air will be forced to rise. As it does so water vapour will condense bringing cloud and rain. On the leeward side of the mountain, the air will now contain less water vapour and so precipitation will be less likely. 3.3 The aspect can also impact on temperatures in a mountain environment. In the Northern hemisphere, south facing slopes will get the most sunshine during most of the day, however northern facing slopes will be more shaded. This means the daytime temperatures for southern facing slopes will be higher than the colder, northern facing slopes. 4. What are mountain landscapes like? Mountain landscapes are an excellent example of how the Earth’s major physical systems all work together over very long periods of time to create the mountain landscape features we can see today. To really understand what mountain landscapes are like, you will need to apply your knowledge of a number of physical processes such as tectonics, rivers and ice. 4.1 Freeze thaw weathering and scree slopes Scree slopes are a collection of broken up rock fragments usually found on the slopes of mountains. When water - e.g. from rainfall or melting snow and ice - becomes trapped in a crack or joint in the rock, it freezes and the ice expands by 9-10 per cent putting pressure on the rock. If this process happens repeatedly, the rock will weaken and eventually shatter into angular fragments creating a scree slope. 4.2 What impact does water have on mountain landscapes? As mountain chains are formed by tectonic process and the movements of the Earth’s crust. The uplifted crust is also attacked by water from the planet’s atmosphere as it flows over the crust as a river. What physical processes create V shaped valleys and interlocking spurs? In mountain environments you often find high levels of precipitation and as a result, the source, or start of many of the Earth’s river systems. As the river moves through its upper course it erodes downwards through the process of abrasion. Over long periods of time, this helps to create the typical V shape you can see in the image opposite. What are interlocking spurs? As the river erodes the landscape in the upper course, it creates a second landscape feature called interlocking spurs. This are formed as the water in the river winds and bends to avoid areas of hard rock. These interlocking spurs, often look a bit like the interlocking parts of a zip. 4.3 What impact does ice have on mountain landscapes? Depending on regional or global climate change, latitude or the amount of uplift taking place, ice may form to create a glacier. A glacier is a mass of ice that moves very slowly downhill. They are found at high altitude, mountains across the globe, even on high mountains close to the equator. Interestingly, glaciers can also be found at lower altitude in high latitudes close to the North and South Poles. The formation of glaciers and the process by which they shape the landscape around them is called glaciation. There are three processes by which glaciation affects the landscape – erosion, transportation and deposition. What are the processes of glacial erosion? Glaciers have a huge impact on landscapes. They exert colossal forces on the land and are responsible for dramatic changes caused by erosion. Plucking 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. Abrasion occurs when rocks and stones become embedded in the base and sides of the glacier. These are then rubbed against the bedrock (at the bottom of the glacier) and rock faces (at the sides of the glacier) as the glacier moves. This causes the wearing away of the landscape as the glacier behaves like sandpaper. It leaves behind smooth polished surfaces which may have scratches in them called striations. Striations are carved out by angular debris embedded in the base of the glacier. How are glaciers formed? - Corries / cirques Corries, also known cirques, are often the starting point of a glacier. The diagram below shows the formation of a corrie or cirque. A corrie is an armchair shaped hollow, high on a mountain with steep back and side walls. After glaciation, the hollow may be filled by a small lake or tarn. Snow gathers in mountain hollows, especially north facing hollows, where there is more shade. This snow builds up and compacts to ice (neve). The action of gravity means the ice moves down the hill. As it goes, it sticks to back walls and plucks rock from the surface. Rocks on the backwalls are loosened by freeze-thaw action. A gap between the wall and the ice develops, called a bergschrund. Ice moving with loose rock acts like sandpaper and deepens the hollow by abrasion. Most erosion is where the weight of the ice is the heaviest. Stones frozen in the base of the ice grind or abrade the corrie base, deepening it. Some of this debris is deposited at the edge of the corrie, building up the lip. These processes create a characteristic rounded, armchair shaped hollow with a steep back wall. When ice in a corrie melts, a circular lake is often formed at the bottom of the hollow. This is known as a tarn What are Arêtes and pyramidal peaks 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 A pyramidal peak is formed where three or more corries and arêtes meet. The glaciers have carved away at the top of a mountain, creating a sharply pointed summit, eg Mont Blanc, The Matterhorn and Mount Everest. U shaped valleys and Glacial troughs Once enough ice has formed, glaciers will move very slowly through the valley system created by water. However, once the ice retreats, it is revealed that the glacier created a distinctive U-shaped valley. These have which have a flat floor and very steep sides. The glacier widens, steepens, deepens and smoothes the existing V-shaped river valleys. The images below show the difference between a U-shaped valley and a V-shaped valley. Just like rivers, glaciers have tributaries. As the main glacier erodes deeper into the valley, the tributary is left higher up the steep sides of the glacier. U-shaped valleys ending with a waterfall at the cliff-face are called hanging valleys. As we saw previously, when a river erodes the landscape, ridges of harder more resistant rock form in its upper course which jut into the river called interlocking spurs. As a glacier makes its way through a valley it’s power is great enough to cut through these ridges leaving behind truncated spurs. Valley floor landforms As a glacier flows over the land, it flows over hard rock and softer rock. Softer rock is less resistant, so a glacier will carve a deeper trough. When the glacier has retreated, (melted) water will collect in the deeper area and create a long, thin lake called a ribbon lake. Many of the lakes in the English Lake District are ribbon lakes, eg lake Windermere. Following glacial retreat, former glacial valleys are often re established as river systems, but as they now have a much wider, flatter valley floor it leads to the formation of flood plains. These are areas of flat land which are exceptionally prone to flooding. However, persistent flooding over time leads to the development of very rich and fertile soil on which to grow crops. 4.4 What do glacial deposition landforms look like? Moraines When glacial ice melts, different types of rock are laid down that have been carried along by the glacier. Piles of these deposits are called moraines Terminal moraines are found at the terminus or the furthest (end) point reached by a glacier. Lateral moraines are found deposited along the sides of the glacier. Medial moraines are found at the junction between two glaciers. 5. How do people use mountain environments? 5.1 Just like hot desert environments, mountains are certainly challenging for humans to survive in and pose specific challenges relating to accessibility, transport, altitude, gradient, food and water supply. We have examined three named groups of people who use the Alps for different purposes. (i) Local inhabitants who use the Alps in a variety of ways, (ii) The positive and negative impact of tourism in the Alps. (iii) Climate scientists examining glacial retreat and the impact of climate change, 5.2 How do local inhabitants use the Alps? Farming Mostly on the valley floor where it is flatter, more sheltered, warmer, with deeper soils Traditionally dairying Main crops re hay and cereals with some vines and fruit in warmer areas Use upland pastures in summer. HEP and industry Industry needing large amounts of electricity, e.g. sawmills, smelters, locate near to HEP stations which generate cheap electricity from the fast flowing streams Traditional industries include clock making, paper and furniture. Forestry Conifers cover the slopes up to about 1800 metres. The wood is used for fuel, building chalets and for paper-making. 5.3 Climate scientists Increasing amounts of CO2 in the atmosphere as a result of burning fossil fuels like oil and gas are enhancing the greenhouse effect and trapping heat in the atmosphere and raising average global temperatures across the planet. The melting of Alpine glaciers and the speed at which they move is acting as an excellent indicator for climate scientists to use as a measure of how much the planet is warming. As the planet warms, glaciers in the Alps begin to melt which causes melt water on the surface of the glacier. Some of the water travels down large cracks in the ice called Moulins. The water flows to the base of the glacier, lubricating the ice and making it move faster down the mountain slopes. This means the glacier sits in lower altitudes, triggering more melting, more Moulins and faster moving Alpine glaciers. 5.4 Impact of tourism Ski tourism has many positive impacts on the Alps such as... Creation of employment opportunities Reduction of migration to larger Alpine urban areas Conservation and protection of the Alpine natural environment Improvements in infrastructure and services in Alpine mountain environment Local Alpine products and cultural identity maintained. However, Ski tourism in the Alps can bring several disadvantages including... Increased use of snow cannons putting massive pressure on water supply in some low lying resorts. Massive energy requirement to spread snow onto the slopes for skiing. It has been calculated that due to snow cannons, a family of four will consume ten times as much electricity on a two-week skiing holiday as they would if they stayed at home! The movement of water onto slopes can negatively impact plants and soil. The use of an additive to reduce the speed of melting from snow cannons has an unknown effect on plants and animals in the Alps. Ski installations do little for the visual attractiveness of the Alps and large ski runs displaces many plant and animal species. 6. What are the alternative futures for mountain environments? 6.1 Mountains as a resource Mountain environments although challenging are an essential resource for humans to use. Mountains are an important component of the hydrological cycle and as a result contribute to the production of resource our fresh water supply. This is because mountains have two important functions, they encourage precipitation and they also store water in the form of glaciers. In terms of storing water, nearly 69% of the planet’s fresh water is stored in glaciers and ice caps which are often found in mountain environments. Secondly, mountain environments force air to rise which means that water vapour in the atmosphere condenses and brings precipitation. This provides essential water for human survival either for drinking, income, energy or growing food. One in two people on the planet depend on mountain water in one way or another. In addition, the fast flowing rivers down mountain slopes can be used to generate hydroelectric power. With their location at some destructive plate boundaries, mountains can also be used for geothermal energy production. 6.2 Management of mountain environments Following your investigations you will have noticed that there are sustainable ways we can manage mountain environments for the future but also ways in which some human activities have led to several negative and unsustainable impacts. Sustainable management of mountain environments Sustainable management of mountain environments would involve using mountains for energy production. Hydroelectric and geothermal energy would could be considered a sustainable use of mountain environments as they would not release any further CO2 into the atmosphere hopefully reducing average global temperatures for the future. As mountain environments will almost certainly remain attractive to tourists, using the principles of ecotourism, similar to desert environments would also be a more sustainable way to use mountain environments in the future. Unsustainable management of mountain environments As you saw when you investigated the impacts of tourism, while it brings some advantages, tourism, if not managed sustainably can lead to several negative social, economic and environmental impacts. As climate change is causing the snowline to creep higher and higher up mountain environments, as it migrates, lower lying ski resorts are becoming less desirable to tourists and further higher altitude resorts are developed. With the snowlines pushed to higher altitudes, similar shifts are taking place in all the other ecosystems found at particular altitudes. Recently scientists have seen an explosion in the number of mosquitoes which can now survive in higher altitude areas increasing the risk of malaria and other diseases in mountain environments. The impact of climate change is also causing glaciers to melt causing problems with longer term sustainability of water supply from mountain environments. The future of mountain environments like the Alps are very much connected to the impacts of climate change a world with warmer average atmospheric temperatures. Mountain environments exam practice Justify why mountain environments can be described as extreme (2marks) Describe three characteristics mountain environments (3 marks) Suggest reasons why mountain environments are often represented in media such as paintings, music, literature and film (4 marks) Name and describe one landform or physical feature in a mountain environment. You may draw a labelled diagram to help you (4 marks) Name one physical process which shapes the landforms in a mountain environment. Describe this process and explain how it shapes the landforms. You many draw a labelled diagram. (6 marks) Describe three ways in which people use mountain environments (3 marks) Explain why mountain environments are challenging for different groups of people (6 marks) You have been asked to organise an expedition to a mountain environment. Identify and justify ONE essential survival item that you would take (2 marks) Identify ONE source of information that you found useful when studying a mountain environment. Explain how it helped your understanding of the extreme environment. (2 marks) Name an area of a mountain environment that you have studied. What would be your feelings about staying there? Explain your views, using specific information about the area. (6 marks) In what ways do you think mountain environments may change in the future? Describe and explain the impact of these changes. (8 marks) To what extent are you optimistic or pessimistic about the future of mountain environments? (8 marks) For a named mountain area you have studied: i) describe how it is used by people and explain why it is used that way (6 marks) ii) To what extent is the use of this area threatening to either indigenous cultures or the natural environment? Explain how climatic change may cause problems for people in mountain environments (4 marks) “Global warming blamed for loss of animal habitats” 27 February 2007 Outline sources of carbon dioxide in the atmosphere, and explain how the theory of global warming could be responsible for one of the headlines above. (9 marks)