My Science School

Maybe you have used oil on your bicycle chain to keep it from squeaking. Did you know that oil was once part of the earth? It starts as a thick dark liquid called crude oil that is found between layers of rock deep inside the earth’s crust. Crude oil is also called petroleum.

Crude oil is a fossil fuel. This means that it started forming millions of years ago from dead plants and animals that had lived in the ocean. Over millions of years, these dead plants and animals piled up on the ocean floor. Thick layers of sand and soil covered them. The sand and soil squeezed together under their own weight and the weight of the water pressing down on them. They were pressed so hard that they turned into rock. Scientists believe that the weight of the rock helped turn the piles of dead plants and animals into oil.

People today use oil for many things. They use oil to heat homes and to run cars, planes, trains, ships, and trucks. They also use oil to make such things as medicines and plastics.

Oil companies get oil by drilling into the earth’s crust. They pump out the oil that is trapped under the earth’s surface. They even pump oil from under the ocean floor.

Because of its many uses, oil has become very valuable. But it takes millions of years for the earth to make more oil, so we need to make sure we don’t waste it.