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Why did America become involved in Vietnam?
- To support the French who were struggling to regain control
-They first gave France $3billion of financial aid from 1949-54
-The French had been driven out after it was one oftheir colonies by the Japanese
-Ho Chi Minh declared Vietnam an independant republic - 2nd Septemer 1945
March, 1945 the French army was destroyed by the VietMinh at Dien Bien Phu
-France wanted to reimpose the colonial rule from before WW2
-They gave France economic support until '54
- To halt the spread of communism which was their main aim, they were worried about the domino effect where all of the Asian countries would start to change.
- To support Diem who is the corrupt leader of south vietnam when in the Geneva Conference in 1954 they decided that Vietnam would split into two. They supported him because he was against communism. He called the National Liberation Front to unite the south against the Vietcong in the north. Diem was catholic compared to 80% of the Vietnamese being Buddhist. He started the Agroville programme where peasants weere moved to 'safe villages' which were effectively concentration camps. He was corrupt and gave key government roles to family. America disliked him but had little choice but to work with him. Diem would not allow land reform which was what the peasants wanted. They funded the Saigon Military Mission where 1000 military advisors trained the ARVN. Diem lost support due to the Buddhist demonsatrations and was assassinated by the CIA
Why did America become involved in Vietnam? ii
The Gulf of Tonkin incident:
2 August, 1964, in the Gulf of TOnkin, the USS Maddox fired on North Vietnamese torpedo boats that were too close
On the 3rd/4th of august the sailors panicked, fearing they were under attack
Lyndon Johnson, the President didn't believe them though still told Congress that there had been deliberate attacks against US vessels from the North Vietnamese
7th August, 1964, Congress authorised an escalation in US involvement
The event is thought to be an excuse
The Gulf of Tonkin resolution was passed to allow soldiers to allow soldiers to protect American Bases
Operation Rolling Thunder:
Fubruary 1965, the NLF destroyed a US helicopter, and 10 planes so the US launched a massive bombing campaign
Originally they aimed at targets such as bridges but then went on to fly over, attacking NVietnam
Napalm, cluster bombs and Agent Orange was dropped
NLF bought anti-aircraft guns, SAM guided missiles and MiG fighter planes
Developed in 1937 by a Chinese Communist Leader, Mao Zedong, the thory behind it was a smaller and weaker force could drive out a powerful invader
The first phase was to get support from the people
The second phase was to harass and weaken the enemy
The third and final phase was to drive them out by conventional means
Guerrilla tactics- winning support
Winning the support of the local people was a major tactic used by the Vietcong
Men and women were recruited from south vietnam
They lived and worked with the village communities, fully intergrating themselves
They followed a code of conduct to win support where they had to be polite, fair, return borrowed items, not damage crops or flirt with women
They targeted officials of south vietnam whom the villagers didn't like - tax collectors would be kidnapped and killed
The vietcong would work in the US camps, washing and cleaning
They wanted to give the peasants what they wanted, land reform
Due to their integration it made them difficult to locate
In return the peasants hid them and their supplies
Guerrilla tactics- Hit and Run
The Hit and Run tactic was also very effective against the Americans:
The Vietcong stayed close to the Americans so they wouldn't be bombed
They relied on ambush using small arm fire
they struck quickly at own personal risk, targeting 'point soldiers' who watched for the enemy, command officers and radio operators
American or SVietnamese patrols were ambushed and killed or captured
If an enemy was captured they were then tortured and killed
After an attack they would disappear into the countryside or the safety of the villages
Booby traps were used so often the Vietcong's identity was hidden
58,000 troops died in Vietnam
It resulted in very low morale
Guerrilla tactics- Remaining safe and supplies
Remaining Safe from US Attack:
They set booby traps and bombs along the patrol paths rather than fighting face to face
Networks and tunnels were builty below ground where they lived and hid- these catered for the need of the VCong where there were weapon stores, sleeping quarters, kitchens and hospitals
The tunnels were strongly protected and difficult to find with booby traps and trip wires at the entrances and throughout the tunnels
They showed organisation and determination
They wore no military uniforms and to the Americans were indistinguishable from the peasants
Ensure a constant supply of equipment and weapons:
The supplies came from Nvietnam via thousands of routes which were bombed by the USA
The Ho Chi Minh trails went through countries such as Laos and Cambodia
It was 600 miles in length
USA tactics - Hearts and Minds
They USA invested improvement in SVietnam
Peasants were helped with farming methods such as digging drainage ditches
They tried to improve communications by building roads, canals, bridges, schools and clinics
Refugees from NVietnam were provided with homes
Local democracy was encouraged
However most money went to the towns when rural areas should have been the focus
Towns and cities of SVietnam stayed loyal to the government even during the Tet Offensive
It was much less effective in rural areas where the VCong dominated
However more resources went to fighting than winning them over and most good was undone
USA tactics- Operation Rolling Thunder
A concentrated bombing campaign on ket strategic targets in NVietnam, such as bridges, roads and railways in order to bring them into submission
At first they attacked no major cities to avoid interference from the USSR
They hoped the VCong would back down when they saw the military power of the US
When there was no response they changed the 'surgical' strategy to 'blanket' bombing including on the cities. huge B-52 bombers each carrying 28 2-tonne bombs
It occured on the 13th February 1969 for 3 years
The NVietnamese did not back down, bombing was intensified but still did not force a surrender
It only gave the vietnamese something to fight for
It was very expensive
USA tactic- Search and Destroy
Helicopters from the US bases carried a small number of troops for surprise attacks on VCong controlled villages
Fast helicopters gave no time for them to escape or offer resistance
Every home in the village was searched and if there was any sign of a resistance the village was completely destroyed
VCong suspects were interrigated which was brutal and ended in death
American troops used extreme violence and would torture and murder cilvilians for revenge
A complete failure
Americans who were involved sometimes suffered from panic attacks and nightmares
VCong retaliated with 'find and kill' and American
USA tactics- Chemical Warfare
Agent Orange - 'a rainbow herbicide' developed in the US in the 1960s used from 1966 to destroy leaves and undergrowth from the rainforest leaving bare trees, polluted air, soil and rivers in order to locate the VCong
However when the chemical polluted the water supply it caused cancer and mutations in children
Napalm - first used in 1965 against enemy positions where the chemical would burn through skin. It burnt through to the bone and continued until 1970
it made little difference to any fighting and the human cost was half a million and vietnamese children have been born with defects
Human horrors became apparent around the world and was a major reason for the anti-war movement
Success of Guerrilla tactics
The VCong were successful because:
- the identity of the VCong was unknown to the Americans and they could not easily go after them
- the booby traps meant Americans could be killed wihtout having to face the enemy
- having support from the people meant they could be hidden and could be merged with the village people making it harder for the Americans
- the tunnels system hid the vietcong, again making it harder for them to be detected
- the supply routes through other countries with 'dummy routes', tropical cover meant they never closed and had a constant supply
The US were unsuccessful because
- It was unconventional war
- The environment was used against their advantage
- They had little dertimation and morale
- They were inexpeienced as they only had a 1 year call of duty and then more replaced them
The My Lai Massacre 1968 16 march
Why were the soldiers at My Lai?
- A search and destroy mission looking for the VCong, 9 US helicopters brought 3 platoons
- 1 platoon was led by Lt Calley who advanced into the village claiming that the village sheltered and supported the enemy and were assured that all were 'VC or VC symapthisers
What happened at My Lai? - wanted revenge
- Eye witness accounts suggest there were no men other than the elderly and children but that did not stop them from killing 500 innocent civilians that were unarmed (officially 137)
- Everyone seen was shot, some were first rounded up in ditches
- Women were gang *****, houses burnt and victims mutiliated with 'C Company' in the chest
- There was no resistance from the villagers
What happened to the US soldiers? - US heard 18 months later
3 US servicemen who tried to convince against the atrocity were criticised by Congress and recieved hate and death threats until 30 years later when they received recognition
Calley was sentenced to a life of hard labour but was released after 4 years
A soldier, Simpson, who had given a statement, commited suicide due to his guilt
Anti-War - TV and media
- Vietnam was the first war that had uncensored coverage that would appear on the TV and extensively in newspapers 'living room war'
- At first feedback was positive and in 1962 'Times' magazine praised it as a 'remarkable US military effort' and American soldiers, were singled out for praise. 'Green Berets'
- In 1965 CBS had shown American fighters on thatched roofs with Zippo lighters and 1968 was the year of the Tet Offensive so Americans had to face up
- February, 1968, Wheeler wrote an article about the fears and bitterness of the soldiers
- There was a growing feeling of defeatism which turned to horror when hearing about My Lai
- Soldiers' testimony and coloured pictures turned people against the war
- 79% of people dissapproved and they had lost the moral highground and were labelled 'baby killers'
Causing the movement:
- 1/4 of reports showed dead bodies,
- Before 1968 most reports were pro-American
- It may have been that it followed public opinion rather than causing it
- However it was substantially formed by Americans seeing pictures
Anti-War - protests
- Many men didn't want to fight and there was resentment to richer middle class Americans who dodged the draft by going to college, abroad or medical disability certificates. So men tore up or burnt conscription papers in public
- August 1968, 10,000 demonstrators in Chicago went to the Democratic Party Convention
- November 1968, 35,000 people protested outside the white house
- 1971, over 300,000 vietnam veterans took part in a protest march against the war
- Further protests occured over the invasion of Cambodia and Lt Calley's trial
- 1965, a student group called Vietnam Day Committee organised a 36 hour sit in attended by 30,000 students and dozens of leading pacifists gave talks at California Univeristy -burn
- Norman Morrison, 31, set himself on fire under the window of the secretary of defence
- October 1967, 100,000 marched to Lincoln Memorial (attacked by police with 647 arrests)
- The 'Great Society' Programme was cancelled due to the huge cost of the war ($20billion)
- The Muslim Group Nation of Islam questioned why black people should have to fight for a country where they had no equal rights
Impact on Anti-War
They attracted media attention and helped focus people's attention on that war- seeing the veterans against it made Americans realise the horrors
Anti-War - Kent State, 1970
2 May - Over 1,000 students attended a protest, causing damage to one of the buildings
4 May - More protests occured with even more students
- The National Guard was called and Tear Gas was used on the students but retreated when the students began to throw rocks and the tear gas began to run out
- 4 students were shot dead
- 9 students were injured
- Later evidence was found that the dead and injured students were no a part of the protest
Imapct on Anti-War
It shocked the USA as it was against the key rights of democracy and the right to protest
It caught the media's attention which led to further demonstrations and strikes
The government began to realise they may not be able to continue with so little support
Anti-War - The Fulbright Hearings, 1971
William Fulbright was chair of the Senate of Foreign Affairs Committee and was a powerful body in government
In 1971 the Committee considered proposals and advice to end the war in Vietnam
There was an investigation into the atrocities of the war
This was official with no hippy feel
Lead up to the end - Media, Cost and Draft
- First war to appear on TV the next day without cencorship
- Walter Cronkite, a TV presenter sad: 'We are mired in stalemate'
- 79% dissappreoved of Calley's court martial
- 1/4 of reports contained pictures of dead bodies
- $20 billion each year
- In 1964, President Johnson had to cancel his 'Great Society' programme of state welfare and good homes
- As MLK said - 'It costs half a million to kill a Vietcong soldier; but we are only spending $53 on every poor American back at home
- There was lots of resentment and were forced to fight, this would not have helped morale
- Morale was so low more soldiers were treated for drug use than actual fighting wounds
Lead up to the end - protests, morale and defeatis
- tactics used affected innocent civilians, search and destroy mission turned to atrocious acts
- chemical warfare destroyed the area and wildlife and caused cancer and also mutations for generations. Napalm was even used on children
- Operation thunder killed innocent people
- 58,000 Americans were dead and there was no progress
- Students- sit ins and protests focused attention
- Draft Cards were publicly burnt
- the war was dragged out to an unexpected length
- the death count of Americans was high
- America had lost the moral highground
Tet offensive, 1968
North Vietnam organised the Tet Offensive and the VCong carried it out:
- The Americans could have argued they were winning the war in 1967 as there were only 1/2million VCong and most cities were under the control of the ARVN. 100,000 VCong had been killed and NVietnam were under the stress of blanket bombing
- the Tet Offensive was launched for mysterious reasons, the north wanted a peasant rising and the North wanted to take over the war effort and quickly end the war
- It was a surprise move because the conventional warfare was unexpected and it was during the Tet holiday during a truce where 1/2 of the ARVN were away on leave
- Occured 31st January, 84,000 troops attacked a hundred towns and cities. A 15-man suicide squad held the embassy for 6 hours. The northern town of Hue was occupied and SVietnamese collaberators were executed. It took 25 days to recapture (3000 civilians died and 75% of the houses were wrecked)
- The 'credibilty gap' opened as what the public saw on the TV from real accounts and what they were told by their government was different
Who won the Tet Offensive?
- There were three major offensives, January, May and August
- The ARVN were taken by surprise
- The American Embassy was captured
- Hue was occupied and held for 25 days
- US public lost faith
- There was large scale destruction in SVietnam
- 45,000 losses to the NVA with the most experienced fighters killed
- The VC were destroyed in SV
- The NVA morale fell
- The ARVN didn't crumble
- There was no peasant uprising
No one won as no one gained anything
1968 - New American Government and US pressure
1969- Richard Nixon became president
- Nixon wanted to bring the troops home without abandoning Vietnam
- However Nixon had little intention of actually ending the war- but make their part less obvious
- The policy was known as Vietnamesation' where the ARVN would protect the south so less troops would be needed
- Johnson did not stand after the Tet Offensive
- He 'brought the boys home'
Continued US pressure on North Vietnam to force a negotiation
- Nixon continued to finance the ARVN with unlimited resources and bombed the north
- he was not afraid to escalate the war and used the 'madman' theory to scare the vietnamese they would not be afraid to use nuclear weapons on them
- They had been secretly bombing NVA bases in cambodia and laos in 1969 but the following year 100,000 US and ARVN forces invaded and captured huge numbers of supplies. It was all done to get the negotiations
Vietnamisation and effects of withdrawal
- From 1969, Nixon ordered gradual withdrawal of troops to be replaced by the ARVN
- They would be replaced by all men between 17-43 who would be trained and equipped by the US and by 1971 400,000 troops had left, leaving a force of 150,000
- However, commanders still believed the war could be won
- Nixon knew it would decerase US casualties
- it seemed to work until 1972 due to the set back of tet
- In 1972 the South was invaded by soviet tanks but held up dui to bombing attacks in the north which were to do with US intervention
- January 1973 a ceasefire and peace agreement was reached between the north and the USA
- Everyone realised there would be no victor
- The US army had to withdraw, prisoners of war to be released, there was to be a vote of independence and the north were allowed to keep the places they already had in the south
- April 1974, the ARVN asked for more aid as the economy collapsed but it was reduced
- March 1975, the NVA invaded the south and the ARVN collapsed
- Thieu resigned and the communist troops marched into Saigon
- 1/2 million left on boats or rafts and many drowned
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- In 1914, men from all over the country rushed to join the army.
- Some thought the war would be an adventure and that they would come home as heroes - inspired by the soldiers in their uniforms.
- This was encouraged by the idea of Pals' Battalions - soldiers could stay with their mates so it seemed like a holiday at first.
- Most people thought that the war would be over by Christmas.
- Many people joined up out of patriotism - they wanted to do their duty to their country.
- However, by 1915 recruitment rates began to drop, and eventually there weren't enough people enlisting to replace the soldiers that were injured or died at the front.
- This could be because people were beginning to realise that the war would last a lot longer than anticipated.
- Also, people were returning crippled and injured from the front and families were hearing about their dead relatives.
- There were also the first bombing raids in December 1915.
- Therefore conscription was introduced in 1916.
- All single men aged 18-40 had to join a military service.
- It was later extended to married men.
- Conscientious objectors - people who refused to enlist because they believed that war is wrong.
- Some e.g. Quakers objected for religious reasons.
- They had to convince a court that their feelings were genuine and not just cowardice. If they could not, they were treated as criminals.
- They were often sent to do non-combatant war work such as driving ambulances.
- They were disliked in Britain because many people felt that they were ignoring their duty to their country and were angry because their relatives had to fight.
DORA - The Defence of the Realm Act 1914
The government had to ensure that:
- there were enough resources to fight the war
- British people could fight and support the war
The act allowed the government to:
- take control of important industry e.g. coal mining
- take over 2.5 million acres of land/buildings (for farming)
- introduce British Summer Time to allow more daylight working hours
- control drinking hours/strength of alcohol
- introduce conscription
- censor newspapers and letters from soldiers
- enforce rationing
The Munitions Crisis 1915
- The Munitions Crisis of 1915 was a massive shortage of shells, bullets and armaments on the Western Front.
- Lloyd George was appointed munitions minister and tried to solve the problem by forcing skilled workers to stay where the government needed them.
- Trade unions protested by saying that bosses of the government's supplier firm were making a profit while workers could lose money if the government sent them somewhere with less pay.
- Lloyd George promised everyone that they could have their jobs back after the war.
- In 1914 Britain imported much of its food from the Empire.
- However, German U-boats began sinking boats that were shipping supplies to Britain.
- This meant that by 1917 there was a severe food shortage - only 6 weeks' supply of grain remained.
Lloyd George tried to solve the problem by:
- having navy convoys for merchant ships - this meant that the number sunk by the U-boats decreased from 25% to under 1%.
- encouraging farmers to grow more food. The Women's Land Army, a massive farming work force, was set up in 1917.
- introducing rationing.
- Optional rationing was introduced in 1917.
- Then in 1918 rationing became compulsory for beer, butter, sugar and meat.
- People were given coupons to hand over when they purchased food. If they had used up their coupons, that was it for the week.
- Some people hoarded food, worried about the rising prices.
- Some people used this food to sell on illegally later, creating a black market in food.
Women at War
- In 1914 the government saw women as supporters of men - they hoped that they would persuade them to join up.
- In 1915 they were beginning to see women as servers to fill the jobs of absent men.
- From 1916 the country was relying more and more on women, especially after conscription was introduced, to fill the roles of the missing men and get the country up and running again.
- Organisations such as the Women's Land Army and the Women's Auxiliary Corps made them more actively involved in the war effort.
Problems Faced by Women
- The food shortages posed a problem - prices were rising and queues were lengthening. They often sent servants and children to queue for long hours.
- Also, for the first time women were responsible for finance. Rents were rising and they needed to find the money to pay.
- They were helped by separation allowances - weekly sum paid to wives of servicemen. This was converted to a pension if the man was killed at the front.
- They often had to deal with the death of loved ones.
- Women had the opportunity to show men that they could be independent and could take on "men's jobs". This was a contributary factor towards them getting the vote in 1918. The 1918 Representation of the People Act gave women over 30 the right to vote.
The government thought that the way to keep the people supporting the war was to keep information from them that might turn them against it.
- Newspapers and letters from soldiers were censored - information that could reveal unwanted troops was cut out.
- Reporters were not allowed to see battles.
- There were no casualty figures available.
- There were no photos showing the dead.
Propaganda during the war aimed to:
- boost the morale of the people
- create hatred and suspicion of the enemy
- encourage civilians to get involved in the war effort
Examples of propaganda:
- Posters e.g. famous "Your Country Needs You" poster featuring Lord Kitchener
- The War Propaganda Bureau got leading writers to produce pamphlets.
- Propaganda films produced by Ministry of Information e.g. "The Battle of the Somme" (1917)
- Even toys and comics for young children promoted the idea of the brave British and the cowardly enemy.
How effective was propaganda?
- Half a million men joined the army in the first month of recruitment.
- The war was not publicly criticised until late 1916.
- Half of the population read daily newspapers and circulation went up e.g. from 1914 to 1918 the Daily Express sales went from 295,000 to 579,000.
- Patriotic organisations were set up e.g. the Victoria League
- The population was surrounded by the government's view - indoctrination.
How effective was propaganda?
- Soldiers knew the truth - the posed photographs were laughed at.
- More and more people began to oppose the war after the Battle of the Somme.
- There were no obvious successes on the Western Front until 1918.
- The government could not hide the crippled soldiers and bereaved families.
- Rationing was unpopular.
- Taxes increased.
- The end of the war was treated with relief rather than triumph.
Attitudes towards Germany
- By the end of the war, the British people had realised the financial and human cost of it.
- They blamed this on the Germans and wanted them to be treated harshly at the Paris Peace Conference.
- However, some people were worried about having to fight another war if the Germans wanted to seek revenge in the future.
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Processes and Factors influencing climate
Hot and semi-arid environments are characterised by having high temperatures , low precipitaion and sparse vegetation. An Arid environment has less than 250mm of annual rainfall, as a semi-arid environment has between 250-500mm of annual rainfall.(Aridity Index take into account evaporation and transpiration losses)
Temperature- during the day under cloudless skies intense solar radiation heats the ground , which warms the air by conduction (transfer of heat loss or gain through direct contact) or convection (transfer of heat through conective air moments). At night under clear skies terrestial radiation (radiation emitted from earth) rapidly escapes and the ground cools , which then chills the air by conduction. The reason why the areas have high temperatures is because they are located at low latitudes , as here radiation is more concentrated and second the solar beam has a shorter distance to travel through the atmosphere and therefore is less diluted by reflection , scattering & absorption (however hotter than at equator as at equator there is nore cloud cover). Different arid areas experience different temperatures due to their latitude , height above sea level , distance from sea & albedo (% of solar radiation reflected, as opposed to absorbed , by the earths surface). Deserts located in middle of continents heat up and cool down faster than those by the seas so therefore greater temp. range. Sakt-encrusted , dried out lake surfaces reflecy more solar radiation than areas of dark rock (absorbs more). Offshore currents depress temperatures. - Sun is more overhead tropic deserts so os warmer. Precipitation varies and can be in the form of coastal fog , flash floods (triggered by intense heating of ground and convectional activity)
Factors Causing Aridity
- Latiude= affected by subtropical high pressure cells which are found about 30 north and south of equator. Air in the cells are subsiding & becomes compressed and drier. Subsidence also prevents air from rising from the ground surface , cooling , condensing and forming cloud and rain. Occasionally sub-tropical air allows up-draughts to rise forming thunder clouds and flash floods (developed over sea - however influence extend to land)
- Offshore Winds= ARID AREAS LOCATED here prevailing winds blow from land to sea and carry little moisture
- Continentality= areas in centre of land masses are dry because they are remote from rain-bearing winds which collect moisture from the sea
- Relief= mountain ranges block passage of rain-bearing winds. Moist air is forced to rise on windward side of mountain which cools and condenses to produce cloud and rain. Leeward side is dry as most moisture has been lost, also the air when descending becomes compresses and becomes warmer and drier
- Cold Offshore Currents = depress coastal desert air temperatures, cold air holds less moisture than warm air so rainfall on land is limited. Instead air above the cold current is chilled and produces advection fog (created when warm air comes into contact with cold surface)- fog carried inland and eventually dissipiates . Fog is frequent as it is trapped under an inversion layer(where air temp rises rather than falls with height), by sinking air in a tropical high pressure cell- when fog condenses it adds to plant growth and weathering processes
Seasonal rain in semi-arid areas
Rainfall occurs when as at the equator intense heating causes air to rise , expand , cool and condense producing heavy rainfall. Area of high rainfall and winds is known as INTER-TROPICAL CONVERGANCE ZONE. At altidude the air spreads about , it then at 30 degrees N &S of equator it begins to sink and as it sinks other air compresses it making it warmer and drier , the sinking air creates a zone of subtropical high pressure , when the air reaches the ground moves towards the equator - HADLEY CELL
Polar front = about 50 -60 degrees S &N of equator where cool air from the poles meets warm air from sub-tropical high pressure cells producing rain
Winds - have an influence of landforms. In the centre of a sub-tropical high pressure cells or anticyclone is calm , but circulating around them are global winds. The winds shift seasonally with the migration of the sun , which means for part of the year an arid may be calm but at other times it is windy. Monsoon winds affect arid areas which are drawn towards continents in the summer. Mountains by obstructing wind flow create local winds on their leeward sides and can also funnel winds.
Climate and weathering
Insolation Weathering = high temps during the day heat up the surface layers of the rock which expand while at night they cool and contract- repeated cycles cause layers to peel and flake known as 'onion-skin weathering', heating and cooling of well jointed rock 'block disintergration' ('granular disintergration' dark minerals in granite) - repeated heating and cooling process called insolation weathering
Crystal Growth = weathering in porous sedimetary rocks such as sandstone. High temps draw saline groundwater to surface that then evaporates - salt crystals grow between the joints and lead to block and granular disintergration - causing flaking
Wetting & Drying = occurs when there are flash floods or seasonal rain encourages clay mineral in rocks to swell- repeated expansion & contraction causes rock disintergrate
Frost Shattering= freezing and thawing of water between joints causes shattering-scree
Solution = water dissolves minerals such as salt which is then removed in soloution
Oxidation = oxygen dissolved in water reacts with minerals such as iron to create oxides and hydroxides- red staining on rocks- minerals that are oxidises increase volume which weakens rock
Climate and weathering
ALVEOLES (small hollows 5-50cm , occuring in clusters with thin pairtrons) & TAFONI (hollows a few metres across developed along lines of weaknesses) , crystal growth , wetting and drying and hydration , wind scouring & case hardening (a hard layer of salt encrusted rock formed where salts have been brough to the surface by capillary action)
Pedestral Rock (isolated pillar of rock) formed by salt crystal rock , high evaporation rates draws water to the surface capillary action , the salts from case-hardening protects the top of pedestral rock , while rocks below are weathered- also form where a harder cap rock protects and is less weathered than less resisitant rocks below.
Pressure release - is the gradual removal of the surface layers of rock can cause those underneath to expand which produces lines of weaknesses where other weathering processes can take place . Pressure release can cause formation of inselbergs (upstanding masses of crystalline rock that project above the plains)
Uluru is an example of an inselberg on a central plain in Australia. 340m above ground, 2.5km long , and 0.5km wide and made out of sandstone . Flaking of rock surface due to insolation weathering and crystal growth. Rock layers etched with tafoni. Rock appears red as water has dissolved the iron. Pressure release cause for sheet fractures - 2km thick. Curved slopes formed at base of slope by chemical weathering e.g. hydrolysis when climate was warm and wetter.
Role of wind in shaping land forms
Deflation erosion - wind picks up and removes unconsolidated material creating deflation hollows (large , enclosed depressions) salt pans (flat areas encrusted with salt) desert pavements (surface of stones resting on a finer material such as silt/clay)
Corrasion erosion - sand carried in wind abrades rock surfaces producing sculptured rocks and ventifacts ( wind-polished stones)
Attrition erosion - sand grains collide with eachother and become smaller (amount of erosion depends on strength , duration of wind & struture of rocks)
Wind erosion creatures features such as yardangs , steep crested , linear ridges of rock parallel to the prevailing winds. They are found in groups and ridges are seperated by wind-scoured grooves. They develop in soft rocks which are easily eroded such as clay as well as resistant rock such as limestone. They have shape like upside down boat, end facing wind is highest and broadest, and vary in height. Abrasion smooth pits and grooves on the side of the yardang , while deflation helps form shape. e.g Kharga Egypt
Role of wind in shaping land forms
Wind Deposition- wind transports sand in different ways small particels are moved by suspension , sand-sized particles move in a series of hops on the ground by saltation (main way) , heavier particles rolled along the surface by surface creep. .
Winds pick up sand from near rivers and lakes and seas and it is carried huge distances into deserts where it is deposited. 60% of worlds sandy arid environments are covered by sand seas (contain variety types of dunes).Dunes develop around obstacles such as rocks, or where a rough surfacre such as sand causes friction and deposition (or where winds come from different directions). Shape and speed of movement of sand dune depends on by strength and direction of winds, volume & grain size of sand supply , shape of land and presence of vegetation. Sandy areas without dunes are called sand sheets dune type found here called 'zibars'. Sand dunes can be fixed anchor dunes formed around obstacles such as a rock or free tunes where no obstacles are present, further sub-divided into tranverse dunes where sand movement is normal to wind direction or linear dunes where sand movement is parallel to the wind
Namib is a desert which is compromised of gravel plains , isolated inselbergs and dune fields
Seasonal Rainfall is often heavy and therefore water runs across the surface rather than infiltrates. Little vegetation to intercept rainfall and high temps bake soil to crust
Wadis are a landform formed by water erosion are a dry river valley with steep sides and a wide floor covered with channel deposits. It forms when flash-floods creates an ephemeral river (temporary). High discharge and avalibilty of lose ,dry sediment in the channel bed encourages the transport of large amount of sediment. Amount of discharge downstream is reduced as storms are localised , some water evaporater or infiltrates river bed. As discharge declines stream loses its competence and BRAIDING (river split into smaller channels) occurs. They vary in size.
Canyons - a gorge with a deep , narrow channel bounded by resistant rocks. Valley occupied by exogenous river(a pernament river) , aridity limits weathering and erosion which preserves steepness of valley sides . Deep canyons form when area experiences tectonic uplift. Seasonal rainfall & flash-flooding causes the river discharge to vary and when low it cannot carry load so braiding occurs. USA has variety of 'canyon-land' type landforms , steep sided plateaus of rock called mesas and smalles 'buttes' are common
SALT PANS , PLAYAS , SABKHAS are feature of water deposition and are all flat and low-lying with little vegetation and parly occupied by saline lakes ( due to precipitation & surface run off fill the lake). When the lake dries out the clay floor cracks and curls up. Water evaporates leaving behin deposits of sodium chloride and calcium carbonate. Plants which are salt-torelant occupy the edges of the pan.
Playas and Pans vary in size. When the lake dries out , salt weathering loosens the material on the floor of the pan which is then eroded by the wind. The material is then deposited as a crescentic , lunette dune on the downward side of the pan. Other pans form when animals over-graze around waterholes or develop in depressions between linear dunes. Term playa and pan are can be used for the same purpose. Sabahka refers to a type of salt pan fringing .
- Ephemerals - plants remain as seeds until rain falls and then they germinate, flower and seed within a matter of weeks- they are small with shallow roots
- Succulents - e.g. cacti- cope with drought by storing water during in their fleshy leaves or stems during seasonal rainfall - reduce transpiration (loss of wtaer vapour to the atmosphere) by closing stomata during the day and open them at night when it is cooler. Many have thick or waxy leaves or cuticles which act as a waterproofing to reduce water loss. Many succulents have CAM which allows them to carry out photosynthesis when their stomata are closed during the day
- Phreatophytes- obtain water from long roots which extend to ground water below the table e.g. mesquite bush which grows beside streams and salt pans
- shrubs and trees have small leaves and spines to reduce transpiration losses - some plants lose their leaves in the dry season but their green stem continues to photosynthesise e.g. Palo Verde
- Plants grow in salt pans and are called halophytes - and grow in saline soils
- acacia tree have evolved spines and thorns to protect them from over grazing- sodum apple contain bitter poisonous latex which animals avoid - creotose bush give off toxic substances to deter other plants from growing nearby
- Small & light in colour
- highly mobile so can travel long distances to find water e.g. gazelles
- some animals are nocturnal to avoid heat of the dayhe.g. golden mole- lizards shade under rocks
- many store water in their tissues , often as fat and may concentrate urine to reduce water loss
- desert foxes have large ears with veins close to the surface to increase heat loss
- reptiles & insects have hard skins to reduce moisture loss
- insects have long legs to keep their bodies away from sand
- insects have mechansims which enable fog to condense on their bodies
- camels store fat in their humps - large water capacity - thick lips and mouth so can eat thorny plants - long eyelashes protect eyes from sand storms - padded feet so can walk on hot sands
CASE STUDY SONORAN DESERT ECO-SYSTEM
- The Sonoran desert is roughly the same size as the United Kingdom and is located over Southern California , Arizona & Mexico
- The Sonoran desert is so dry due to the lack of moisture in the air and this is because though the Pacific Ocean lies just to the west but the coastal mountain ranges effectively stop most moisture reaching inland. To the South- East lies the Gulf of Mexico any moisture from there must travel 1700km and cross the continental divide before it reaches the Sonoran desert. It is a difficult place for moisture to reach and therefore it there are little clouds as there is a lack of moisture.
- A common drought enduring small tree growing on the upper slopes is called the Palo Verde , the plant loses it leaves in the dry season , while it greens bark enables it to carry out photosynthesis. Lower gentler slopes are covered with creosote bushes, which have small , dark resinous leaves to reduce transpiration. They have roots which reach down vertically and out horizontally in order to collect as much water as possible. The leaves have a type of varnish on them so that they can seal in moisture. The smell and taste of the plant puts off any animal from trying to eat it. Plant spacing is controlled by water availability, that is creosote bushes grow further apart when supplies are scarce . Ephemerals such as the brown-eyed primrose commonly grown among the creosotes bushes. Phreatophytes , such as the mesquite bush , grow beside streams and on the edges of salt pans. Halophytes such as inkweed, salt grass and pickleweed occupy saline soils on salt flats. Where water reaches the surface , such as along the San Adean fault , groves of Californian fan palm grow. Their very large leaves indicate water supply is plentiful and there is no need to conserve supplies. The Saguaro Cactus when it rains they collect water using their spines and a horizontal web of roots. The water is then stored in the stem to sustain the cactus, until the next rains come. The cactus can lose up to 82% of its water before it dies of dehydration. The ocotillo , looks dead but is awaiting for the next rain
CASE STUDY SONROAN DESERT ECOYSYSTEM
- The rain arrives in the desert in two distinct seasons , in the winter cold wet fronts from the Pacific are sometimes strong enough to bring rain to the desert despite the intervening mountains. In the late summer warm wet air from the gulf of Mexico sometimes makes it over the continental divide and is swept in over the desert often forming thunderstorms.
- Soils in the desert are thin , relatively infertile and alkaline. Seasonal rains leach soluble salts down through the soil which are drawn up again under high evaporation in the dry season. Flash-flooding can compact soil creating impermeable surfaces. Salt flats in the Salton Trough are covered with thick crusts of sodium chloride, gypsum and calcium carbonate.
CASE SUDY - SONROAN DESERT
Disturbances - Due to water being pumped out and used in cities parts of Arizona are literally sinking into the ground , the dry rock compacts and the surface sinks – massive line sand holes in the soil . The soil does not stretch well so there are great tares in the earth.
- Many of the deserts rivers have dried up – water and many riverside habitats have disappeared and with them the wildlife-many animals on the verge of extinction
- Towns and people will have to move soon as there is little water- turn into ghost towns
- Many farms and towns and cities now in the desert such as Phoenix- use of lots of water
- More wells have been built underground as more people move to the desert – water table had dropped by nearly 3m a year and is still dropping- pumping out more water be=is becoming more expensive and the water quality is poor and is not sustainable
- In 20 years population of the state has doubled- Houses have water features – new houses – all need water - Use water from Colorado river
CASE STUDY - HUMAN DISTURBANCE - SONROAN
- Cities such as Phoenix have replaced deserts covered with cacati
- taking water from rivers and groundwater absatraction to supply for a growing population has affected mesquite bushes + cotton wood trees
- road construcion and gas and water pipes have displaced natural habitats- fenced highways restrict movement of animals - prevents pronghorn reacin water supplies
- trampling and off road vehicles damaged soil and vegetation
- intoduction of non-native species such as a tamarisk has displaced native cotton woods. Bufle grass spread for Mexico to Arizona- occupies gaps in sparse vegetaion cover- increasing fuel load and fire risk- in 1994 engulfed 1150 acres of Saguaro National Park-20% saguaro cactus destroyed
- Saguaro cacus sometimes illegally removed and used as a garden ornamental as well as desrt toroises
- generates forein currency earnings - benfits countries with few other resources
- creates direct employment and indirect mployment -multiplier effect
- encourage local people to learn new skills (Tunisia hotel traiing schools)
- tourists spendings hlp to preserve or revialise tradionals crafts and rituals
- develops infrastructure such as roads and water supply
- preserves natural landscape e.g. Kuene National Park proects threatened black Rhinos
- jobs are often low paid and low skilled - jobs are seasonal
- tourist revenue transferred overseas , dont benefit host country-'all inclusice packages'
- over reliance of tourism is risky as for the terrorist attack on red sea - Shalm-el Sheik
- tourists who behave badly or dress inapproprialey cause offence to local people - shorts
- local culure customs and rituals e.g. aboriginal dances are simplified for a tourist audience
- discharge of untreaed sewage from hotels into sea or local water supplies causes illness
- high demand of water in hotels - laundry , swimming pools e.g. golf courses Palm Springs
- rubbish is an eye sore and endangeres wildlife - helicoper rides GC disturb wildlife & pollution- damage ancien sites
CASE STUDY : THE VALLEY OF THE KINGS
Ancient egyptian tombs on the west bank of the Nile are under pressure from tourism.
- Large no. of visitors visit the tombs each year and their raises the humidity in the tomb sofetning the plaster so it no longer sticks to the wall - people touching or brushing against paintings cause damage
- Irigation of sugar cane is causing problems as water-table rises , saline water evaporates into the tombs and salt crystals grow - in 1990 one tombs ceiling collapsed - rising water-tables and visitor pressure has led to the closure of one of the finest tombs - Seti I
- Efforts to reduce tourists impact included , dehumidifiers , placing glass screens in front of the paintings and closing tombs on a temporary basis to allow humidity levels to fall, numbers entering the tombs are controlled and popular tombs such as Tutankhamen have a higher entry fee
- A new visitor centre opened in 2007 which should help spread visitor flow
- Paths have been widened between tombs to prevent overcrowding - and not to damage soils
- Movin car parks and replacing tarmac roads with those of sand and gravel so they are less visually intrusive
- Future option include - extending opening hours , limiting no. of tomba tourists can visit are possible options to reduce overcrowding
- involving local people in managing toursist facilities e.g. aboriginies at Uluru work as rangers
- creating national parks to protect landforms , plants & desert animals
- controlling visitor numbers at popular sites e.g. Valley of the Kings
- establishing tourist codes e.g. entering Arches national park visitors reminded removal of rocks and artiefacts is prohibited and also not feed wild aniamls or drop litter
- restoring historical sites using entrance fees
Agricultural opputrunities and challenges
- Hunting & gathering still practiced by some indeginous people but where water is scarce main agriculture is nodasim (a wandering form of existence in search of good pasture and water for livestock, collection of fruits and roots)
- rivers which flow through deserts e.g. Nile provide oppurtunity for irrigated agriculture e.g. tunisa grows olives , figs , oranges - date palm can produce dences , roofs , mats
- On Niles bank , beans , cotton , rice etc. are all grown- transferring water to fields involves simple dykes to sprinkler systems - Aswan Dam built once seasonal rain and is regulated to ptrovide water for crops growing all year round
- Hydroponic used in Mexico and USA is hydroponics (grwoing of crops without soil)
- Unreliable rainfall , strong winds , thin infertile soil pose serious challenges - drought and mismanagement causes desertification (conversion of marginal land to desert)- human factors include deforestation and overgrazing- demands of poverty and high pop.growth
- another problem is salinisation - when high temps ecourage saline water to be drawn up through the soil and salt crystalises in the upper layers- salt crusts stop root growth , reduce infiltration and increase surface run off - also can cauae waterloggin if a lot in one area- can be managed by salt tolerant plants such as barley and rye
CASE STUDY : AGRICULTURE IN THAR DESERT
Located in Indian and south-east Pakistan , densley populated by peopel and livestock and covers an area of 2000km2. Precipitation varies from 100 - 50mm, much falls in the monsoon season between July and September. It is composed of sand dunes and plains , low hills and saline lakes , Thar vegetated by scrub and scattered trees, wildlife includes Indian gazelle.
- Summer monsoon water is collected for consumption as the groundwater is too deep and saline for human consumption
- Canals cross the area and supply irrigated water for cultivation of wheat and cotton
- Hot dry conditions , strong winds and human activities such as deforestation and overgrazing are causing soil erosion - many livestock (sheeps and goats) overgraze & remove palatable grasses leaving behind inedible plants
- Loss o fplant cover has exposed soils to wind erosion - heavy trampling (waterholes) has compacted the soil , limiting seed development , damaging plant roots and encouraging runoff
- Pop. pressure causes trees and shrubs to be removed and used as building material , fuel and medicine. Deforestation has caused a declin in organic material which normally supplies nutrients and helps to hold soil particles together- once vegetation removed the sun bakes the soil until it cracks and blows away
- Loss of native tree Khejari deprives soil of valuable nitrate fertiliser - crop recover perios is shorter - rising pop.
- In an attemp to stop desrtification and extend the area under irrigation , IGNP Canal was constructed to bring water from the Himilayas to the desert . Irrigated water used to grow crops such as sugar cane- however seepage from irrogation channels resulted in water logging and salinisation- a rise in malaria-indian gazelle decline
To reduce overgrazing in Thar they are being urged to limit herd size , allow grass to recover and improve quality of livlestock- use solar devices instead of dung for fuel and use the manure for fertilisers instead- plant trees such as prosopis cineria is providing timber wood and fuel wood as well as green leaves for camels,goats, sheep. Sand dunes are being stabilised with trees and grasses such as the acacia tortillis-limiting water and recycling water , digging ponds to collect water - lining canals with concrete to avoid seepage underlying issuer how to stop population growth
Niger sustainable agriculture- a poor , semi-arid area in West Africa within the Sahel. Soils cannot produce enough food to feed the population which is increasing by 2.9% per year- practices have tried to be introduced:
- mulching -incorporating vegetation in to the soil to increaae organic matter and to improve infiltration and reduces soil erosion - mulches also stimulate termite activity which breaks up soil- however millet stalks also used for building material, firewood , medicine so farmers use it sparingly - other mulches include andropogon gayanus
- planning pits or 'za'- small holes dug with a *** which collect runoff water & rainwater- small amounts of manure and seed is added
- manuring - mineral fertilsers would increase crop yield however it is very expensive
- intercropping - trees , native grasses and shrubs are planted in strips between millets to act as a windbreak
- bunds - low stone walls built along the contours of the fields to retain earth and hold back water
CASE STUDY: MINING IN THE AUSTRALIAN DESERT
Australia is the leading producers of gold, uranium , titanium , maganese , nickles and opals. Mining provides jobs in deserts areas where there is little other oppurtunities for example Olympic Dam employed 3000 in central Australia. The company owning the mine has contributed $45 million to the South Australian Government which has benefitted the area. There have been improvments in local service and has had the multiplier effect- however local housing prices have therfore increased and people cannot afford to buy them
Aboroginal groups benefit directly if mining takes place on their landby recieving an annual rent. Tracks and roads which companies create allow aboriginal groups to reach remote areas for hunting - however due to rigths some indigenous groups oppose to the new mines
Mining companies face big challenges as moving the ore from centre of Australia to the coast e.g. copper from the Olympic Dam has to be trucked 560km to the port at Adelaide. Modern mining methods use large quantaties of water e.g Olympic Dam relies on water from pipelines from the coast and groundwater resources. Aborignals fear that the water will become endanger rare springs e.g. Lake Eyre- important source of waer in central Australia and are of cultural signifcance for aborgignes
CASE STUDY : MINING IN THE AUSTRALIAN DESERT
Opponents claim there are many environmental impacts , construction of roads, pipelines removes vegetation and soils. The flat relief of deserts mean mining operations are visible for long distances , an eyesore- e.g. Prominent Hill open-cast mining hole is nearly 1km wide and 50m deep- large visual impact. Opponents argue that liquid waste from treatment plants contaminate water and soils. Concern in Beverly which will use situ leaching method to extract the ore acids will be forced into the ground to dissolve and remove uranium- mining creates soil heaps which scar the landscape source of dust
Mining companies aware of their responsabilities carry out environmental assesments before mining. To reduce visual impacts height of waste dumps is limited and re-landscaping occurs when mining ceases. Mining companies recyle water from treatment ponds and spray weeds to control their spread