Oil Formation
Oil is found in areas that are, or once were, covered by oceans. Microorganisms that sank to the bottom of the ocean were covered by sediment. Over millions of years the sediment changed into rock, and the organic matter changed into oil. The oil slowly seeped through cracks in the rocks to form pools, which are the focus of oil exploration.
Uses
The industrialized world relies heavily on oil as a source of energy. Crude oil is refined to produce petroleum, which fuels most of the world's transportation. It is also used to make plastics, roofing, and many other products.
Challenges
Oil drilling is difficult and expensive, and accidents can harm the surrounding ecosystem. Because oil deposits are limited, areas with large oil reserves have seen political conflicts as countries battle for control of this valuable resource. Fossil fuels also produce greenhouse gases when burned, which contribute to global warming. The world is tentatively turning to renewable and environmentally safe sources of energy, including water, wind, and solar power, to replace fossil fuels.