Grace Simon, age 10, of Tucson, Ariz., for her question:

WERE THE CONTINENTS ONCE ONE LAND MASS?

A generation ago, certain thoughtful scientists suspected this to be true. Once upon a time, they suggested, all the land on the planet earth was huddled together in one big continent. They named it Pangaea and placed it somewhere near the South Pole. Through the years they gathered lots of evidence to back up this idea. Other evidence showed how the great land mass cracked apart and how the pieces drifted away to become the continents of the modern world.

At last there was so much evidence that the whole world of science just had to believe. It was shown that the continents drift apart because the sea floors between them are spreading. The long story has been traced back at least 200 million years  when that one big continent called Pangaea really did exist, way down there in the Southern Hemisphere.