Petroleum is another name for oil, a liquid found deep underground. Petroleum is a valuable natural resource. It is used to make many products that people use every day. These products include gasoline, paints, and even lip balm.

How Petroleum Formed

Petroleum formed from the remains of tiny plants and animals that lived hundreds of millions of years ago. When these living things died, they sank into mud. As layers of mud and rock piled up, they pushed down on the lower layers. Eventually this pressure and Earth's heat changed the plant and animal remains into petroleum.

Drilling and Refining

Underground, petroleum collects in reservoir rock. This is rock that has thousands of tiny holes in it. Sometimes reservoir rock has large, bowl-shaped spaces in it. These spaces trap huge amounts of petroleum near Earth's surface. Workers drill down to collect the petroleum from these reservoir rock traps.

After workers pump the crude, or raw, petroleum from the ground, it goes to large factories called refineries. There the crude petroleum is refined, or cleaned, to make it ready to use.

Uses

People use refined petroleum to make many different products. Some parts of the petroleum go into fuels such as gasoline, diesel fuel, and jet fuel. Other parts are used to make waxes and greases such as petroleum jelly. Plastics, fertilizers, explosives, and certain drugs also come from refined petroleum.

Disadvantages of Petroleum

Burning fuel made from petroleum releases harmful gases into the air. These gases can mix with moisture to create acid rain, a dangerous form of pollution. Burning petroleum also helps to trap heat in Earth's atmosphere. This process is called global warming. It may harm plants and animals and cause ocean levels to rise.

In addition, the world has a limited supply of petroleum. Because it forms so slowly, it is called a nonrenewable resource. People are using up petroleum so fast that eventually the supply may be gone.