Susan Dute, Age 10, Of Morrison, Tenn., for her question;

Will the grand canyon ever eat clear through the globe?

The earth's crust is like a bumpy skin stretching over the continents and under the seas. The mountains and valleys, the ups and downs are just surface pimples on this rocky skin. The crusty layer is from 10 to 40 miles thick. The highest mountains are about five miles above the level of the sea, and the deepest trenches in the ocean floor are about six miles below sea level.

The grand canyon is a tremendous ditch in the western mountains. It is a mile deep and some eight miles wide, and it took the busy Colorado River about 50 million years to dig it. But it is a mere scratch in the earth's rocky skin. It would have to be 4000 miles deep to reach the center of the globe and almost $000 miles deep t0 cut through to the other side. And this, of course, could never happen.