Sunday 8 June 2008

Geography notes on second term

Geography notes – earthquake and volcanic eruptions

1) Structure of earth: Crust: outer layer made up by solid rock,60-120km thick and its’ continents and oceans floor. Mantle is the inner layer that made up of molten rock as magma. Core is the innermost layer made up of iron and nickel, it’s very hot and high pressure.

2) The crust broken into plates. They move slowly by the convection of magma caused by thermal expansion, the boundary between plates are called plate boundary. Earthquakes and volcanic eruptions are mainly found along plate boundaries and they are result of boundary movement.

3) When the plates move oppositely, pressure builds up gradually, earthquake is result from releasing pressure suddenlyearth shake violently.

4) Cracks formed from moving of plates, gases, solid rocks and magma may forced out violently though out cracks, this is volcanic eruptions.

5) Earthquakes and ranked according to magnitude and we use Richter Scale to indicate earthquake.

6) Six effect of earthquake: (1)Collapse of buildingsmain cause of death and injuries. (2)Earthquake cause breakdown of gas and oil pipelineswidespread firelots of death and widespread destruction. (3)Breaking of rock, road and bridgedelaying rescue work. (4)It cause subsidence of land, landslides, dams collapseflooding. (5)Earthquake occurring under the sea may cause giant tidal wave(tsunami) and cause coastal flooding. (6)There are still aftershocks after the main earthquake, also victims may suffer from hunger and spread of diseases.

7) Four effects of volcanic eruption: (1)It release gases and most of them are poisonous and harmful to the health (e.g.). (2) Large rock fragments are thrown out as volcanic bombs and volcanic ash is released also, they buries building and farmland. (3)Hot magma flow known as lava flow destroy and burn everything up the way. (4)Volcanic ash or volcanic bombs may mix with rain water or melting snow and form mudflow and buries house and farmland.

8) Immediate measures: earthquake: send armies and rescues teams to search in rubble, settle them in temporary shelters, give them food, water and blankets, restoring communication, putting out fires and providing medical services.

9) Volcanic eruptions: divert flows away from human settlement.

10) Long-term measures: (1) Use sensitive instruments to give prediction and warning. (2) Use modern technology to make earthquake-proof design. (3)Reducing the pressure of cracks. (4)Land use zoning reduce loss from fire in high-risk areas. (4)Teaching.

Geography notes – farming

1) System of farming: (Input-> process -> output)

2) Types of farming: Types of output: livestock onlypastoral, crops onlyarable, bothmixed. Use of output: feed themselvessubsistence and sold for profitcommercial.

3) South China: small farm, labour input, machinery input, yield per unit of land, yield per farmer intensive farming, output: rice.

4) Australia outback: big farm, labour input, machinery input, yield per unit of land, yield per farmer extensive farming, output: cattle.

Problems of farming:

1) Extremes in rainfall: Australia get less than 500 mm rainfall per year, it’s hard to support growth of crops and large populations of cattle. South China always have typhoonsheavy rain, flooding.

2) Poor soil: In Australia half of land is infertile and in China soil erosion make soil thin and infertile.

3) Pests and diseases may result in crop failure or deaths of livestock

4) In mountainous areas, terrace are common and the land is steep and soil is thin. It’s hard to use machines and output is limited.

5) Australia is short of labour.

6) In China, urbanization happens and good farmland is taken away by houses and factories.

7) In China, farmers other don’t have money to buy machines, good seeds, fertilizers and pesticides. This limited their profit of output.

Ways to solve the problem:

1) Use machines to productivity and instead of labour. Machines can ploughing, sowing, harvesting and even milking.

2) Chemical fertilizers puts back some nutrients back to the soil, Pesticides kills and deter pests, weedicides kills unwanted plant.

3) Development of generically modified crops improve the quality.

4) Irrigation technology supplies water for a large area of farmland and it’s reliable.

The problem of scientific farming methods:

1) Those methods are too expensive that some farmers can’t pay for it.

2) Some of the farmers are poor educated so that they don’t know how to use the methods in correct way.

3) Using machines efficientlycut down tree and bushes to enlarge farm sizethe lost of windbreaks may lead to crop destroying by strong wind.

4) Machine may harden the soil that water may just flow over it.

5) Chemical fertilizers lack of organic matter that used to bind soil togetherafter several time, the soil is loosened and can easily be eroded, also, chemicals made rapid growth of algae in surrounding streams, the fish passing there may lack of oxygen and die.

6) Pesticides are poisonous and people may be poisoned if they eat it, also, pesticides may passed to other living organism through food chain.

7) Poor country can’t afford to research new seed and breeds, GM food are produced by changing/ removing some genes from crops, some people think that it can solve food problem but some think that this may change the neutral environment and hurt their health.

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