Paula Guju, age 9, of Youngstown, Ohio, for her question:

How were the Great Lakes formed?

Those great big silvery blue lakes were not always there. Ages ago, their place on the map was a region of rivers and valleys. One river flowed to join with the Mississippi. Another flowed over what is now Chicago. Another went to join the Ohio River and another flowed on to join the Atlantic Ocean. This is how things were about a million years ago. Then came the cruel glaciers of the Ice Ages. Inch by inch they crept down and covered the old region of rivers and valleys. This place on the map was then covered with a thick, massive sheet of ice.

Those mighty glaciers shifted countless tons of dirt and gravel. They scraped the tops of the hills and dug holes deep into the ground. At last the Ice Age ended and the stupendous glaciers melted. But this part of the earth had been greatly changed. When the heavy glaciers departed, the ground rose higher. Water, lots of water, tried to drain away to the sea. But the melting glaciers had dumped tons of rocky debris to block its path. So the draining water collected in those deep hollows that the glaciers had dug. And this is how the Great Lakes were born.