My Science School

               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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               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.

Picture credit: google