Fossil Fuels: Fossil fuels were formed hundreds of millions of years ago from minerals found in the remains of plants and animals. The process of fossil fuel formation is very slow. They are non-renewable (things that cannot be replaced when used) resources of the Earth. They are categorised into three main types: coal, oil and natural gas. Coal is a solid fuel which is found in mines. Crude oil is drilled out from seas or from offshore sources. And natural gas is pumped out from offshore and onshore sources.
Coal: Coal is a black or brownish-black sedimentary rock formed from the remains of plants and other organisms, which were covered with mud and sand. Millions of years ago, the Earth’s surface was covered with swampy forests. These forests got buried under the soil due to excessive flooding. Gradually, due to the high pressure, the overlying mud and sand squeezed out most of the liquid, leaving behind a pasty mass called peat. Slowly, peat hardened to form lignite and then coal. Three types of coal are: Lignite (low grade), bituminous (high grade) and anthracite (highest quality hard coal).
