David. Martin, age 11, of Pittsburgh, Penn., for his question:

How is oil formed in the ground?

Petroleum, or rock oil is, of all things, a fossil, It is the remains of tiny creatures who lived and died in shallow seas long ages ago. We do not know all the secrets Nature uses to turn this fossil material into precious petroleum but it is believed that it formed where shallow seas were buried under new layers of rock.

The fatty remains of these sea plants and animals went through many chemical changes which lasted for millions of years. The oil near the surface evaporated or oozed out to form gooey pools of tar. The oil trapped underground seeped into the pores and crevices of certain rocks. Where there was a solid cap of rock above these oil soaked rocks it remained safe, counting off the ages until mankind should need it to run his machines.