Oil & Gas
Oil and natural gas were created from aquatic organisms that were buried under ocean or river sediments. Heat, pressure and bacteria combined to compress and "cook" the organic material under layers of silt.
In most areas, a thick liquid called oil formed first, but in deeper, hot regions underground, the cooking process continued until natural gas was formed.
Over time, some of this oil and natural gas began working its way upward through the earth's crust until they ran into rock formations called "cap rocks", which are dense enough to prevent them from seeping to the surface. It is from under these cap rocks that most oil and natural gas is produced today.
Natural gas is very convenient for domestic use as it can be piped directly to homes. It is also widely used in power stations to produce electricity. Transporting gas is clean, however, like all fossil fuels, when burned it adds to the greenhouse gases in our atmosphere.
Oil originally came from natural springs, but since the 1800s drilling took place in oil fields. Unlike gas and coal, oil has to be refined before being used. Its biggest use is in transport – car, bus, trains, ships, aeroplanes – when it is refined to become petrol or diesel. It has also been used to fire furnaces and power stations in the past. It is usually transported by ships. But if their load spills, it can lead to major environmental problems.