William Mahan, Age 10, Of Wichita, Kan., far his question:
Haw did oil form in the ground?
Its name is petroleum meaning rock oil because it saturates the pockets of porous rocks in the earth's crust. We use it to grease the wheels of our machinery, as fuel and for countless other jobs. It is estimated that petroleum provides more than two thirds of the energy needed to keep our age of industry on the move.
It takes nature millions of years to create a reservoir of petroleum. Our scientists are still not sure how the job is done, and so far, we are unable to copy nature's secret recipe for making this rock oil. It is a very complex chemical, and we can break some of its long, thin molecules apart into gasoline, parsfin, kerosene, coal tar and countless other useful products.
A few experts favor the idea that petroleum is an inorganic chemical which forms in the earth's crust. An inorganic material is made from non living chemicals. But most experts think that petroleum is formed from the remains of ancient plants and animals. In this case, it is an organic material and rates as a fossil mineral.
Our present petroleum supplies began to form perhaps 60 to 100 million years ago when the lumbering dinosaurs stalked the earth. We find it in areas once covered by shallow seas. And we know that since time began, such waters have teemed with microscopic plants and animals. A living cell, however small, is formed from the remains of living things that lived in the ancient seas.
Through the ages, the land and the seas have been at war over their border lines. Sometimes the seas slopped over the land and then receded. For thousands of years, vast areas of the land were drowned under shallow lagoons and swampy marshes. Such waters are breeding grounds, and they teem with vast numbers and countless varieties of living things. When the tide of battle turned, the sea water went home to the ocean, and the drowned land was left high arid dry. The little sea dwellers were left to perish in isolated pools, and soon their remains were covered with silty mud and new layers of rocky minerals. Under pressure and heat, the organic chemicals were changed into petroleum. Most of it evaporated, but some of the precious fossil material became trapped in porous rocks. In time, it became the reservoirs of petroleum we find deep in the earth's crust.
The recipe for changing living cells into petroleum took millions of years, and the ingredients were protected in special rock formations. A layer of dense rock, such as shale, formed the floor and sides of a basin which prevented the oozy material frown escaping. A layer of porous rock rested in the solid basin, and the organic ingredients were trapped in its spongy pores. The brewing recipe was then capped with a lid of dense rock to keep it from evaporating into the air.