Darren L. Paxton, age 8, of Summersville, W. Virginia, for his question:

What causes the continents to shift?

The New World and the Old World face each other across the Atlantic Ocean. On a map, you want to fit their two matching sides together like a jig saw puzzle. Ages ago, they actually were joined together in a larger continent. Ages ago they were cracked and pushed apart. It happened because the continenets and oceans belong to the earth's rocky crust. And this global shell is broken into about six large pieces and a number of fragments. The large crustal pieces are called plates and they sit on a rather restless layer below, which is called the mantle.

America is on one plate, Europe is on the next one and the crack between them is down the middle of the Atlantic Ocean. Material from the mantle keeps oozing up through the crack. This spreads new material on the ocean floor and pushes the two continental plates farther apart. So inch by inch, the Old World and the New World are drifting farther apart. In the Pacific, a ridge of sea floor is sinking below and this makes our continent drift toward Asia.