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| Fossil Fuels |
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| The Earth contains many resources which are not being replaced. These resources which are not being replaced are called non-renewable sources. Amongst the most non-renewable resources are the three fossil fuels - coal, petroleum and natural gas. |
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| Fossil fuels were formed millions of years ago. The formation of coal that is mined today started in the carboniferous period, that is about 3 x 108 years ago. At that time earth's surface was covered with dense forests and swamps. As trees and other plants died, they did not rot away completely. The wet airless mud made it difficult for the decay-bacteria to survive. So the half rotted trees sank into the mud and in course of time formed 'peat'. When successive layer of material such as clay settled on the peat, the weight of the clay compressed the half rotten vegetation lignite. As the layers piled up, pressure and heat increased. This resulted in the formation of anthracite in the deeper layers. |
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| All these different types of coal are
known as 'fossil fuels'. Fossils are the remains of things which were living once. They are energy rich molecules of carbon compounds originally made by plants with the help of solar energy. |
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