Terry Darnell Nutt,, age 13, Lena, Miss., for his question:

Does the crust of the earth move?

The crust of the earth fits as snugly as the skin of an orange. However, it is a rather wrinkled and bumpy skin. It humps up into high mountains and swoops down in deep hollows to form the ocean basins. It varies in thickness from about 30 miles to about 60 miles, This crust is, of course, made of rocks. To us they seem heavy. But we are told that they are light enough to float, as it were;, on much heavier rocks below.

The experts also tell us that the crust of the earth may be cracked. It may be broken into huge slabs, somewhat like monster ice floes. Though there are no gaps between these coastal blocks, they do press against one another. They also seem to move in California, one; great coastal block is moving in a southerly direction and its neighbor is moving in a northerly direction. Where these two blocks meet and push against each other we have an earthquake fault. Parts of the earth's crust do move, but very slowly, no more than an inch or two a year.