Darrell Gordon, age 13, of Winston Salemn, N.C., for his question:

WATEVER HAPPENED TO THE MOHOLE PROJECT?

Scientists have determined that our earth is divided into four parts: the outer crust, the mantle, the outer core and the inner core. The thickness of the crust varies from 5 miles under the oceans to about 20 miles under the continents. It is believed that within the deepest part of the crust the earth's temperature may be 1,600 degrees Fahrenheit.

Some years back scientists agreed that it would be valuable to have some samples taken directly from the earth's mantle. A government financed project was established for just such an experiment. The operation was called Mohole.

There's a boundary between the earth's crust and the mantle called the Mohorovicic discontinuity. The name has been shortened to Moho and the hole that was to be drilled was called mohole.

Plans were made to set up a drilling platform located in the ocean, since the earth's crust here would be at its thinnest. The project got as far as drilling a number of test holes. But, unfortunately, the fine plans to be able to study the composition, radioactivity and temperature of the mantle were not to be realized.

In 1966 the ambitious scientific project ground to a halt. Congress refused to provide additional money which was necessary if the operation was to continue. High costs of the project itself frightened many members of Congress since high budgets also had to be met for our space program and the war in Vietnam.

And so the Mohole project was over. It had become a scientific dream that never reached reality. Perhaps someday the work can be resumed.

We know that the earth's mantle is solid rock and that it goes down about 1,800 miles. Without actually having a  hole drilled into it, we also know that the mantle is made of silicon, oxygen, aluminum,.iron and magnesium. While the temperature in the area where it meets the crust is 1,600 degrees Fahrenheit, scientists believe it increases to about 4,000 degrees where the mantle meets the outer core.

Scientists speculate that the earth's outer crust is about 1,400 miles thick and that it is made of melted iron and nickel. Temperatures here probably increase to about 9,000 degrees Fahrenheit. The inner core of the earth is 800 miles thick and probably consists of solid iron and nickel.