Dorothy Loizides, Age 12, Of Newport News, Va., for her question:

Exactly how are fossils formed?

Fossils are the remains and reminders of plants and animals that lived long ago. There are dozens of different kinds of fossils, and the earth has dozens of different recipes for preservirig them. Some are perfect copies of the original life forms, and some are so changed that only an expert can recognize them.

The experts who study fossils are paleontologists. They search for their specimens on the surface and deep in the rocky layers of the earth's crust, on land and on the muddy floors of the deep oceans. A fossil may be the fragile body of a tiny ant, perfectly preserved in a gob of golden amber. It may be the hairy body of a monster mammoth frozen in the ice of a polar glacier. It may be the footprint of an ancient salamander or the impression of a ferny frond that flourished perhaps 100 million years ago.

The formation of a fossil was started by a living plant or animal in the dim distant past. All living things use foods to carry on the magic processes of life. The earth's simple chemicals are built and rebuilt into ce11s, tissues and bodies that grow and multiply. When the life span is over, the plant or animal usually decays. Its ce11s lose their vibrant energy and their fabrics return to the dusty chemicals of the earth from which they were created a few plants and animals escape the process of decay  and these become fossils. A few leave copies or imprints of themselves in the crusty ground. The frozen footsteps of a dinosaur are fossils. Many fossils become changed from their original forms. Petroleum is the fossilized remains of ancient, microscopic sea dwellers. Coal is the Carbonized residue of the earth's early forests.

The old earth used countless different recipes to preserve these remainders and reminders of living things of the past. Bony skeletons were safely cemented in layers of newly formed rocks. Woody tree trunks were preserved in the dusty deserts. Countless plants and animals were protected from decay in bogs and stagnant swamps. Others were frozen in eternal ice fields. Layers of sea shells, large and small, collected on the ocean floors and later became dry land. These became fossilized rocks, such as chalk and limestone.

The paleontologist probes into the history of each fossil specimen. He uses his many skills and his endless patience to learn when the original plant or animal lived and how its fossilized remains were preserved. And every fossil has a different story to tell. When its secrets are solved, it adds one more scrap of information to the fascinating, age old story of life on this luxurious planet we call the earth.