The oil that keep your bicycle from squeaking and the gasoline that keeps your parents' car running both come from deep in the earth's crust. Both began as a thick black liquid found in big pools between layers of rock.
Oil is not a mineral. Like coal, it was made from things that were once alive. Oil is found in places where there were seas and oceans millions of years ago. Tiny plants and animals lived along the shores of these seas, just as they do today. When these creatures died, their bodies drifted down to the sea bottom. Over millions of years, billions of these tiny dead creatures formed deep piles.
Sand and mud settled over the piles of dead creatures and formed thick layers. Slowly, these layers were squeezed together by their own weight and the weight of the water pressing down on them. They were squeezed so hard they became layers of rock. Scientists think that the heat and weight of the rock, pressing on the piles of dead, rotting plants and animals, turned them into drops of oil.
Today, people drill down through many layers of rock to find pools of oil. From oil we get gasoline to run the engines of cars, trucks, and tractors. Many kinds of plastics and other things are made from oil. And it is used to heat houses, factories, and schools.
Because oil was first found seeping up between rocks, it was called petroleum - from two Latin words meaning "rock oil". Today, petroleum is usually just called oil. But it is so important, and worth so much, it has been nicknamed "black gold".
Oil is not a mineral. Like coal, it was made from things that were once alive. Oil is found in places where there were seas and oceans millions of years ago. Tiny plants and animals lived along the shores of these seas, just as they do today. When these creatures died, their bodies drifted down to the sea bottom. Over millions of years, billions of these tiny dead creatures formed deep piles.
Sand and mud settled over the piles of dead creatures and formed thick layers. Slowly, these layers were squeezed together by their own weight and the weight of the water pressing down on them. They were squeezed so hard they became layers of rock. Scientists think that the heat and weight of the rock, pressing on the piles of dead, rotting plants and animals, turned them into drops of oil.
Today, people drill down through many layers of rock to find pools of oil. From oil we get gasoline to run the engines of cars, trucks, and tractors. Many kinds of plastics and other things are made from oil. And it is used to heat houses, factories, and schools.
Because oil was first found seeping up between rocks, it was called petroleum - from two Latin words meaning "rock oil". Today, petroleum is usually just called oil. But it is so important, and worth so much, it has been nicknamed "black gold".
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