- Created by: hannah
- Created on: 03-04-12 12:04
MOUNTAINS! High Altitude + Remoteness
- High altitude makes air thinner, meaning there is less oxygen to breathe in.
- Less oxygen can lead to difficulties with breathing and aititude sickness (feeling really sick, dizzy and disorientated)
- High altitude makes the temperature really cold, this can lead to frost bite, hypothermia and forms of immobility.
- remotness in mountains can make travel difficult difficult because of the rugged terrain, this makes it hard to get to anyone that needs medical attention or resources.
What makes an environment extreme?
HOT LACKING OXYGEN
How are mountains formed?
- Mountains are formed by slow but gigantic movments of the earth crust. The earth's crust is make up of 6 huge slabs called plates, which fit together like a puzzle.
- When 2 slabs of the earths crust smash into each other the land can be pushed upwards forming mountains.
- These are mainly collision or distructive boundries.
What is mountain climate like?
- The higher the altitude the cold it gets, the temperature falls roughly 0.6'C every 100 metres
- Mountains fource air to rise and cool forming clouds with increase the chances of pecipitation.
- A mountain acts like are barrier to the wind. Weather on one side can be very different to the other.
- The aspect (the direction in which the mountain faces) is different on either side of a mountain and can affect how much sun it gets, for example east facing slopes get sun in the morning but not in the afternoon
Animals and wildlife in mountains
- At the bottom of the mountain you will find a weath of vegetation and animals species, the higher up you go the more specialised these plants and animals have to become.
- Animals and plants have to adapt if they want to survive the harsh climate condtions higher up the mountian. Some plants have to grow close tot he ground so they don't get blown over or freeze, some animals adapt by hibernating or insulating their bodies with fat or wool.
- Some animals develop larger lungs to deal with the low oxygen levels ar high altitude.
Weathering- Freeze Thaw
- Water seeps into cracks in rocks.
- When the temperature falls below 0'C the water turns to ice and expands.
- As it expands it forces the rock apart and widens the crack. Eventually the ice will melt and the rock will break apart.
Weathering- Onion skill/Exfoliation
- During the day the temperature can heat up the minerals in the rock
- Surface layers of rock are heated and expand in the day
- At night temperatures can reach below freezing point so the surface layers cool and contract, along with the rock minerals. This causes the rock to weaken.
- The surface layers will spilt or peel away like an onion.
- Plant roots can get into tiny cracks and can physically open them up further. In addiction, decaying plant roots also produce acid which can chemically eat away rock
- Burrowing creatures also help to break up softer rocks.
A glacier is a mass of ice that moves slowly downhill under the force of gravity. Ice forms when snow accumulates in mountain hollows and valleys and is compressed due to weight.
There are 3 main types of glacial erosion
- Freeze thaw
1. Plucking- Plucking is when water from a glacier freezes around lumps of cracked and broken rock. When the ice moves downhill, rock is plucked from the back wall.
2. Abrasion- Abrasion is when rock frozen to the base and the back of the glacier scrapes the rock bed.
3. Freeze Thaw- Freeze Thaw is when water gets into the cracks in the bed rock, usually the back wall. At night the water will freeze and expand causing the crack to to get larger. Eventually the rock will break away.
In an exam you might be asked to describe particular landforms or features found on mountains and explain how they are formed through some of the physical precesses above. Here are some landforms:
- Pyramidal Peak- A pyramidal Peak is a mountain top, carved and steepened by weathering and erosion forming cirques around it.
- Arête- An arête is a ridge formed where two cirques cut back into a mountain.
- Cirque or Corrie- A cirque or corrie are a steep-sided hollow deepened by the action of ice.
How a Cirque/ Corrie is formed
This is how a Cirque/Corrie is formed (this is a good example to use in an exam as it uses a number of physical processes including freeze thaw, erosion, abrasion and plucking).
- Freeze thaw, plucking and abrasion may occur at the same time. Corries are often the stating point of a glacier.
- Snowflakes collect or accumulate in a hollow. Gradually as more snow falls the snow is compressed and the air is squeezed out to become firn ( rounded and dense).
- With the pressure of more snow the firn will eventually over years become glacier ice.
- Erosion and weathering by abrasion, plucking and freeze thaw will make the hallow bigger
Who lives in mountain environments?
Case study- The Himalayas
The Himalayas passes through five nations: India, Pakistan, china, Bhutan and Nepal. The Himalayas are the worlds largest mountain range. Its peak is of 8,000 meters, which is approximately 26,000 feet. There are 14 such peaks of The Himalayas and hundreds of summits, which are around 23,000 feet high. The mountain range stretches 1,700 miles across an area between Assam and Kashmir.
Nearly 40 million people inhabit The Himalayas. Generally, Hunduis of Indian heritage live in the Sub-Himalayas and the Middle Himalayas valleys.
To the north Tibetan Buddhist inhabit the Great Himalayas. In central Nepal, in an area between about 1,830 and 2,440 the Indian and Tibetan cultures have intermingled, producing a combination of Indian and Tibetan traits.
The best known of the high mountains people are the Sherpas who inhabit the central and eastern regions of Nepal. The Sherpas are now employed as guides for mountaineering expeditions.
How people in the Himalayas live and survive- Econ
The major industries include:
- processing food grains,
- making vegetable oil,
- refining sugar,
- brewing beer
Fruit processing is also important. A wide variety of fruits are grown in each of the major zones of the Himalayas, and making fruit juices is a major industry in Nepal, Bhutan and in the Indian Himalayas.
Many of the Sherpa's (mostly men) are now employed as guides for mountianeering expeditions. Trade played an important role in the lives of the frontier in Ladakh, Himachal, Kumaon and Garhwal.
Since 1950 tourism has emerged as a major growth industry in the Himalayas. Nearly 1 million visitors come to the Himalayas each year for mountain trekking, wildlife viewing and pilgrimages to major Hindu and Buddhist sacred places.
How people in the Himalayas live and survive- Tran
Historically, all transport in the Himalayas has been porters and pack animals. Porters and pack animals are still important, bu the construction of major roads and development of air routes have changed the transitional transportation patterns.
There are no railroads though.
How people in the Himalayas live and survive- Food
MAIN CROP= RICE
Other major crops include-
Food production in the Himalayas has not kept up with population growth. Most communities face malnutrition.
Clothes are made out of animal fur and skin to keep them warm in the extreme cold.
How people in the Himalayas live and survive- Serv
Literacy rates are low because of lack of school and skilled teachers.
Healthcare is very basic and many communities still rely on herbal remedies. Hospitals and emergency care is normally quite far away.
Most communities face a shortage of safe drinking water.
Who else visits the Himalayas and what challenges
- Extreme sports events (The Tenzing Hillary Marathon runners)
You will probably be asked in the exam to give examples of how mountain environmental can be challenging to different sets of people and how people cope with challenges. You might also be asked to list and justify some equipment you could take on an expedition. This list should help:
- Spiked boots- to help keep grip on difficult icy terrain
- Wind proof jackets- to protect against extreme weather and wind chill
- Lightweight Oxygen cylinder- to help breathe at high altitudes where oxygen levels are thin.
Others include an ice axe, a compass/GPS device, shovel, rope, helmet, multi layered clothing, insulated gloves
Tourism and its impacts
- Tourism provides jobs are locals and extra income (money)
- Remote areas gain better infrastructure and development (due to increased money and numbers)
- Ares will become more well known and companies will pour money into them to help them survive and become more sustainable (more basic services and facilities put in and provide more environmentally friendly methods of farming and living.
- Tourist compete with local people for services and facilities.
- Tourist walk particular mountain trails are wear away vegetation
- Loss of trees and vegetation increases erosion by rain which leads to landslides
- Tourism is an unreliable employer. People are laid off in the low season or when tourist numbers fall
- Tourist drop litter and make areas look unsightly and dangerous
- Tourist disrupt local cultures and traditional way of life.
TOP TIP- It's always a good idea to give a range of advantages/disadvantages including economic, environmental and social/cultural impacts
Ecotourism in Nepal- a solution to the problem
The fragile Himalayan ecosystem is in a threat due to environmental degradation. The region is losing its precious forest which have resulted in soil erosion and other related problems. Tourism is the major cause of deforestation in the Himalayas as firewood is the main fuel used for cooking and heating in the mountains. Plastic bottles, plastic packs, glass bottles and other garbage from trekkers is having adverse effects on the region. Awareness about ecotourism is low on the mountain villages. Due to the effort of many organisations working for eco friendly travel practices, people are getting more aware of ecotourism but the efforts are not in the proportion of the problem.
Nepal is also a culturally rich country with dozens of ethnic groups (mostly living in the mountains where the tourist go of trekking) having there own cultures. As the people are poor and not very conscious of the values of their culture, they are quite vulnerable to tourist cultures
How do people react to mountain environments?
This film Touching The Void is an example of the sort of challenges mountaineers face in the mountain environments. It also shows us people's reactions to extreme environments and the feeling provoked include, anxiety, fear, upset, exhaustion, delusion, excitement, relief.
In the exam you might be asked to give an example of a source that you have found useful in class and why. This is a good example to give as long as you give reasons for this. Others might include Bear Gryll's extreme survival series, or particular paintings, poems or pictures you have found insightful.
DESERTS! What are hot deserts?
Deserts are vert dry and hot. They are defined as areas with an average annual precipation of less than 250 millimetres (10 inches) per year. However this is an average figure and it may not rain for several years. The largest hot desert in the world is the Sahara, in north Africa. Other deserts around the world include the Kalahari (southern Africa), the Atacama (South America), the Gobi (Asia) and the Australian Desert.
Case Study: Sahara Desert
Location: North Africa, covering large parts of Algeria, Chad, Egypt, Libya, Mali, Mauritania, Mororcco, Niger, Western Sahara, Sudan and Tunisia
The Sahara divides the continent of Africa into North and Sub-Saharan Africa. The southern border of the Sahara is marked by a band of semiarid savanna called the Sahal
Where are hot deserts found?
Location: They are found close to the Tropic of Capricorn and the Tropic of Cancer- lines that run parallel to the equator at about 30' latitude.
Deserts form at 30' latitude due to areas of high pressure where air is sinking. The air stays very close to the ground and water vapour doesn't have much chance to rise and cool. We need rising and cooling (found with low pressure) to create clouds and rain, so without it we get a very dry arid environment.
What are hot deserts like?
Climate: During the day the average temperatures are over 30'C but sometimes temperature of over 50'C have been recorded. During the night time temperatures drop sharply to below freezing.
These are known as diurnal temperatures- that vary from highs of the day to the cool of the night.
Question point- Why do temperatures drop so dramatically at night in the desert?
This is because hot deserts rarely have any clouds and without clouds to act as a blanket all the heat given off in the day can escape when the sun goes down, meaning temperatures plummet near to freezing.
Hot desert climate graph
Always describe at least 3 points on a graph!!
- Temperature is at its peak (highest) during July, approximately 37'C
- From August to December the temperature falls from 37'C to 15'C
- June, July and August are months that have no rainfall at all.
TOP TIP: Always remember to use figures to back up your points and make sure you refer to both temperature and rainfall!!
The main challenge for living things in the desert is the lack of water. Plants adapt to arid conditions by devising ways to find and store water.
Xerophytes- have physical characteristics that help them to survive. best known as cacti.
- Spikes rather than leaves
- Thick waxy skin
- Large fleshy stems
- Extensive root system
- White upper surface
Ephemerals- plants that change their behaviour to suit the desert climate
- They can lie dormant for months, even years until it rains and then grow quickly.
- Some plants can grow, flower and produce seeds within just a few weeks.
Animals adapt to arid conditions by devising ways to find and store water.
- Some avoid heat by burrowing into the sand soil
- Some are nocturnal (only active when its cooler and at night) e.g. small rodents
- Animals that can't escape the heat by burrowing. Are designed to stay cool, conserve water and cope with the harsh environment. e.g. a camel
- A camel has long, powerful legs, tough leathery knee pads (to prevent scolding when kneeling), broad and flat hooves, two rows of long eyelashes (to prevent from sand, wind and heat), nostrils that can close, fat it can store in humps, thick woolly fur, capacity to drink up to 50 litres of water in a few minutes.
Messa (spanish for table because these Salt Pans
features have flat tops like a table)
Desert pavement Sand dune
Is the decay and disintegration of rocks, soil and minerals through direct contact with the earth's atmosphere.
Examples in the desert include: Insolation weathering and Freeze-thaw weathering
Insolation weathering is caused by heat from the sun (insolation). Minerals in the rock heat up and cool down at different rates. This puts the strain on the rock and leads to block disintegration (when the rock splits along joints) or exfoliation (when layers of rock peel off, like onion skin)
Freeze thaw weathering happens when moisture collects in cracks in the rock. When temperatures drop below freezing at night this causes the moisture to freeze and expand which widens the crack until eventually the rock splits.
A similar process happens when when moisture draws salt out of the rock and then evaporates. The salt expands as it crystallises and the rock splits. This is called salt weathering.
Landforms created by weathering and erosion: Mesas
Mesas are formed by weathering and erosion of horizontally layered rocks that have been uplifted by tectonic activity. Variations in the ability of different types of rock to resist weathering and erosion cause the weaker types of rock to be eroded away, leaving the more resistant types of rocks sticking out higher than their surrounding. As water and wind continue to erode the mesa, it becomes smaller in size until it is no longer wider than it is tall. At this point it is known as a butte.
~Is the wearing away of rocks due to transport wind, water or ice.
The biggest force that influences erosion in the desert is the wind, it does this in two ways:
- Deflation- The gradual removal of sand and dust to leave a flat surface or hollow in the rock
- Abrasion- The sandblasting effect of sand particles carried in the wind, which can erode the rock into unusual shapes.
Most rivers in the desert flow intermittently(not consistently) , usually after heavy rain. This leads to flash flooding. Run-off from the land rapidly fills the river and the fast flowing water erodes rock to form steep sided valleys and gullies.
Landforms created by wind erosion: Desert Pavement
Desert pavements are surfaces of stone, tightly packed together, that rest on finer material such as sand. The wind picks up and removes finer materials such as sand and sometimes if the wind is strong enough small pebbles. The larger, coarser particles that are too big for the wind to pick up are left behind. Eventually the surface will almost entirely be formed of coarse, heavier materials that is costly packed together on the surface which then acts as protection for the finer particles of sand underneath it again erosion. This forms an appearance like pavements.
Landforms created by water erosion: Wadis, Canyons
Wadis are dry river beds the form temporary channels following periods of high seasonal rainfall and flash floods. Wadis usually have steep sides and a wide channel floor. High discharge (high volume water) and steep channels mean that rivers often have a lot of energy for erosion. Sediment (material) picked up and transported by water can further scour the river channel (sand paper effect) widening and deepening it.
~ The laying down of material (by wind, water or ice) that has been eroded.
In the desert wind and water are the main agents.
- Wind carries fine particles of sand and deposits them as sand dunes. If the wind continuous to blow it moves the sand and changes the shape of the dunes.
- During flash floods, rivers remove large amounts of materials and deposits it further along the valley, or across the flood plane.
Landforms created by deposition: Sand Dune
Sand dunes resulted from the build up of sand blown into moulds and ridges by the wind. They usually form around an obstacle on the ground such as a rock, a bush, or even an abandoned vehicle. The wind transports sand (in the direction of the prevailing wind) and other fine grained material but when it hits the obstacle it loses energy and drops the sand it is carrying. Soon the obstacle becomes covered in sand on the windward side and continues to grow. These sand particles blow up the windward slope and falls down the leeward slope where it is deposited.
How do people use the hot desert?
High temperatures throughout the year, plenty of sunshine and little rainfall make arid areas ideal holiday environments. Tourism in these areas covers a range of different activities.
- Many arid and semi-arid coastline have been developed as resort areas for beach tourism for example resorts along coastlines of the Persian Gulf.
- Much of the desert tourism in South West USA is focused on viewing dramatic desert landscapes and scenery such as the Grand Canyon. People often use Las Vegas (a city in the desert) as a stop off point to reach national parks and desert environments.
- Culture tourism in Egypt is based on ancient Egyptian civilisation and the pyramids attracts millions of visitors a year.
- Extreme sports such as sand boarding, 4x4 Jeeps and cycle races across the Sahara desert are popular too.
Benefits and Problems
- Tourism brings in money and employment
- Money helps to development infrastructure such as roads, railways, airports, gas and electricity
- Areas develop and modernise
- Environment damage to natural landscapes (e.g. Foot erosion in Grand Canyon national parks)
- Overcrowding and unsustainable use of resources (e.g. Las Vegas which already has a water shortage has further pressures placed on it by increased water use associated with tourism and recreational pursuits)
- Off road vehicles and adrenaline sports activities destroys the terrain and natural environments.
- Indigenous tribes (nomads) become commercialised and lose their own cultures.
When winds blow across a mountain range the air loses its moisture. The mountains act like a barrier and this creates a rain-shadow effects of the leeward side (away from the wind) Deserts are therefore formed due to lack of moisture and precipitation.
Winds that sweep in from the ocean are full of moisture. As these wet winds move over land they rise, cool, and release the moisture as rain. But some places are simply too far from a coast to reap the benefits of those moisture laden winds. By the time they've swept across hundreds and hundreds of miles and reach the middle of a large land mass, nearly all the moisture has already fallen. An example of this is the Gobi desert in Mongolia.
Coastal desert are formed when cold waters move from the Arctic and Antarctic regions regions towards the equator and come into contact with the edges of continents. As the air current cools as they move across cold water, they carry fog and mist, but little rain. The air doesn't rise and high pressure is created. An example of a coastal desert is the Namib desert.
High pressure/Trade wind deserts
Hot air rises at the equator (low pressure) and sinks in the subtropical areas around 30' in both hemispheres. Here the air begins to descend towards the surface in the subtropical high pressure belt. The sinking air is relatively dry because its moisture has already been released near the equator.
How do people use the hot desert?
Lots of people use hot deserts in different ways. Different groups that use them include:
- Nomads and other residents
- Travel companies
- Large companies extracting resources
There are many tribes that live in deserts around the world. The Bedouin are examples of nomads that live in deserts across North Africa. They are pastoralist that herd sheep, goats and cattle. They are known as nomads because they move (migrate) throughout the year to find fresh pasture for their animals to graze. In winter when there is some rain, they travel deeper into the desert. In summer when the water is scares they try to stay close to a reliable water supply.
TOP TIP- Always try and include the name of a tribe in your answer like The Bedouin tribe!!
How nomads mange to survive: Water and Transport
Tribes such as the Bedouin plan their journeys across the desert between water sources such as Oases and they have a range of tactics to find water such as looking for lines of plants growing in the desert so they can mark the routes of a river flowing underground. They also look out for pigeons or doves as they only live near water.
Nomads need to be able to move on at any time and carry all their belongings with them, so they use camels. These animals are able to carry heavy loads and walk long distances in the desert without need to stop and refuel.
How nomads mange to survive: Clothing and Shelter
The Bedouin traditionally make their cloths from wool of their animals (they provide insulation from the heat during the day and from the cold at night.
Both men and woman wear long, loose fitting clothes to allow air to circulate around the body and prevent sweat form evaporating too quickly, to stop dehydration.
A tent makes the idea home for most tribes. Low tents made of goat hair cloth usually provide waterproof and warm bases that can shelter against the wind.
What challenges do they face?
- Exploitation of natural resources such as oil and gas
UN issues desertification warning:
Desertification could displace up to 50m people over the next decade. Tens of millions of people could be driven from their homes by encroaching deserts, particularly in sub-Saharan Africa and Central Asia.
Desertification is the extreme deterioration of land in arid areas due to loss of vegetation and soil moisture. Desertification results from man-made activities and is influenced by climate change. It is mainly caused by overgrazing and exploitation of groundwater (using too much for irrigation or to support a population). All of these processes are mainly a result of overpopulation (not enough resources to support the number of people living there).
Most of the causes act like a flowchart (one factor influences another that influences another and so on...)
- Drought: lower rainfall than usual...
- Soils become dry and there is no water left in wells...
- Trees die, grass withers and its replaced by poor desert scrubs...
- Crops fail and cattle feed on poor pasture...
- Less roots to protect the topsoil, less humus; soil becomes more sandy and dry...
- Wind erosion removes the soil causing dust storms, leaving bare rock.
- Population is high and increasing fast...
- To increase food supplies more crops are grown and more cattle graze the land, leading to over-cultivation and over-grazing...
- Yields decline as the soil has less nutrients and cattle are undernourished and can die...
- Demand increases for fuel supplies...
- Less vegetation; more dry, bare soil; more wind erosion so new plants can not grow and bind the soil together.
Case study: Desertification in the Sahel
Location: The Sahel is shown by the belt in dark orange in the picture below. It stretches 3860km across Africa and countries including Mauritania, Mali, Niger, Chad, Sudan and Eritrea.
The Sahel is home to more than 50 million people but it is still one of the poorest and severely degraded places on Earth. Since the mid twentieth century the Sahara Desert has expanded southwards into the Sahel at a rate of 2-5km per year. It suffers from severe drought and average rainfall is between 200mm to 6mm. In June 2000, drought in the Sahel caught media attention. Six African countries faced devastation, with crops and livestock wiped out. Ethiopia was the hardest hit with no rain for three years. 300 deaths were recorded in Ethiopia in March 2000mainly from famine and diseases caused by a lack of food and water.
Human causes of desertification in the Sahel:
A natural green belt of bushes and trees extends across much of the Sahel and protects the region from the Sahara desert to the north. However this zone could easily be destroyed by cutting trees for firewood.
As population has increased, traditional lifestyle are no longer carried out (the involves moving around and growing vegetation in different areas). Population growth, over grazing, deforestation and exploitation of water resources have all resulted in desertification.
'Slash and burn' has particularly caused desertification! This is where farmers cat and burn natural woodland to clear areas for farming. This exposes fields to winds that blow the topsoil away and erode the soil making it poor and unstable to grow crops to feed the population.
Oil and Gas exploration in the desert
People use the desert to get to the valuable natural resources such as oil and natural gas which can be found in them, particularly in the middle east. These resources have created a lot of money for the countries involved so naturally huge companies and businesses are attracted to desert regions.
Beneath the sand are layers of sedimentary rock. Trapped within them are oil and gas from the remains of microscopic animals that died millions of years ago. Slowly the oil and gas rose through the porous (permeable) rock until they reach a layer of impermeable rock and could not rise any more.
Large companies such as Shell and BP therefore have to drill down to reach these valuable resources.