Why is forestry important?

               Trees are an important natural resource, because there is a constant demand for timber for building, for paper and other purposes. In developing countries wood is used as fuel for cooking. Even waste wood can be chipped and mixed with an adhesive under high pressure to form large flat building boards.

               Tree felling in some areas has resulted in large-scale deforestation, often followed by erosion. With no tree roots to stabilize it, the soil is washed away by rainfall.

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Can sunlight provide power?

               As we use up natural resources such as coal and oil, there is a constant search for new sources of energy. The Sun gives out vast amounts of energy, of which only a tiny fraction reaches the Earth. If we could use just a small part of this energy it would fulfil all the world’s foreseeable needs for power, but so far it has not been possible to find efficient ways to collect solar energy. We harness the Sun’s energy with solar panels. This energy is then used to heat water.

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How do we obtain oil?

                Oil is thought to have formed from the remains of organisms that died millions of years ago. Billions of tiny organisms lived in shallow water or in the surface layers of the oceans. As they died their remains settled to the bottom and were eventually buried. The remains were compressed under the weight of rock. They underwent chemical changes due to the high pressure and eventually formed oil and gas, which remained trapped under the rock layers.

               Geologists locate deposits of oil, and holes are drilled so the oil can be extracted. Usually, water is pumped into an oil well under pressure, forcing the lighter oil up to the surface.

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How is coal formed?

               Coal is formed from the compressed remains of plants that lived in bogs 250-350 miff on years ago. This was during the Carboniferous Period, when primitive animals first appeared on the land. Coal formed from the remains of tree ferns and other primitive trees, which were covered with mud and sand and buried as new rock was laid down. Very gradually, over millions of years, this material turned into coal.

               A similar process is taking place today in peat bogs, where the rotting remains of heather form peat. When dried, peat burns in a similar way to coal. In some parts of the world soft shale, which is called brown coal, is mined. The hardest and most pure form of coal is anthracite, which contains very few impurities.

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How is gold mined?

               Gold is unusual because it is found in its metallic form, rather than as a chemical compound. Metallic gold, which is easy to identify and shape, has been mined for thousands of years. Most gold is found in what are called alluvial deposits. They consist of river mud containing tiny particles of gold washed out of rock over thousands of years. Water currents are used to wash away the mud and gravel, leaving the heavy gold particles. Gold is mined in many parts of the world, but most modern gold supplies come from countries such as South Africa and Russia.

               Gold does not tarnish, and this makes it very valuable.lt is used mainly for the manufacture of jewellery and for coating electrical contacts. It is also a very good conductor of electricity.

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