Ronald Koring, age 10, of Lancaster, enna., for his question;

What is the source of the Great Lakes?

On the map, the Great Lakes look like a blue orchid corsage pinned on the chest of North America. When you see them from the shore or sail on them, they look like the ocean. When you swim in them, however, you know they are not seas. For seas are salty and their clean, clear waters are fresh,

The vast Great Lakes hold the biggest single supply of fresh water in the; world. They hold far more water than the whole Mississippi or Amazon rivers. You would expect this great reservoir of fresh water to be fed by mighty rivers and countless streams. But no such sources of water show on the map.

Only a few smallish rivers and a number of streams empty into the Great Lakes. Yet the lakes are always brim full and spilling over. They supply the endless torrent that spills over Niagara. They supply the waters of the wide St. Lawrence river, always racing to pour itself into the sea.

The water which fills the Great Lakes, or most of it, comes from below. Their floors reach right down to the ground water trapped below the surface,, This is the same water which keeps a deep well supplied with water.

Ground water is rain and melted snow which has seeped through porous rocks and soil. For water will run downhill whenever it can. even through the soil. Rainwater settles only when it reaches a layer of solid, dense rock through which it cannot seep or trickle.

The roots of the Great Lakes dip down into a vast and endless supply of ground water. Water seeps through their floor and sides and countless underground springs also gush up from below. The lakes are connected with each other. Their waters join together and pour off down the St. Lawrence river to the sea. And still the ground water pours in from below to keep them supplied.

Magnificent as they are, the Great Lakes are but a small event in the long history of the earths face. Geologists have pieced together their past and are ready to make some guesses about their future. A few million years ago, the whole region was a waterway of rivers and valleys. Some  the streams emptied into the mighty Mississippi and others flowed into the North Atlantic. The Great Lakes did not exist.

Then came the Ice Age. This region of rivers was frozen and crushed under glaciers two miles thick. The gentle river valleys wore gouged into deep basins. When at last the; glaciers melted, they stuffed the old valley outlets with debris and the deep basins filled with water to form lakes ‑the Great Lakes.

The ground is still changing and in a thousand years, Lake Michigan. may be forced to join the Illinois and Mississippi rivers. In fifteen hundred years, only Lake Ontario may be left to fill the St. Lawrence River. All the others might well be flowing into the Gulf of Mexico,