Tami Bryan, age 14, of Montgomery, Ala., for her question:
HOW CAN PETROLEUM FORM UNDER THE SEA?
The first petroleum wells were drilled on dry land, and we got used to this idea. However, so much oil was taken from the land that we had to search for new supplies in unlikely places. Now we are told that offshore drilling under the sea is necessary to supply our future energy needs.
Most geologists agree on how and when the earth's buried petroleum was formed. If their theory is correct, we would expect to find most of the precious oil buried under the sea. For this is where the earth started the recipe that created it.
Petroleum is a rich mixture of assorted hydrocarbon chemicals. These are the so called organic chemicals created by the living cells of plants and animals. Often they survive in the ground through hundreds of millions of years. These organic hydrocarbons are fossil materials, which is why petroleum is called a fossil fuel.
Through the long ages, the earth's enormous oceans have teemed with multitudes of mini plants and animals. The mini¬plants used the energy of sunlight to create food and oxygen for themselves and also for the mini animals. And through the long ages, these tiny life forms lived and died in countless generations.
Life, we are told, began in the earth's ancient seas. Gradually the remains of simple little sea dwellers sifted down to the ocean beds. There they formed oozy deposits of organic chemicals. The oily substances were mixed with silty sands and various inorganic, or nonliving, minerals. Changes in the earth's crust often buried the oily deposits below heavy layers of rock.
Gradually, with time and heat and pressure, the oozy old deposits were changed to precious petroleum. In the meantime, the restless earth continued to remodel its crust. In some regions the old sea beds lifted high and dry above the water. In some regions the sea retreated, and the old sea beds became dry land.
It seems, then, that all our petroleum deposits originally were formed under the sea. The ones we found first are in land areas that once were swamped by fresh or salt water.
If this theory is correct, perhaps most of the earth's petroleum deposits are still under the sea. This explains why oil men want to go ahead with offshore drilling. They suspect that the richest deposits are in shallow, sunlit water near the coasts. Other deposits may be out in deeper water but they are harder and more costly to reach.