Bill Giolltto, age 12, of Rockford, I11. Ill,, for his questions.
What are kettle lakes?
A kettle lake is related to a kame, an esker and a drumlin. No, the; do not belong to world of greinlinss All of them are daughters of glacial drift which at last gives us a clue. For we know that glacial draft is the assorted debris left by glaciers. One of the most fascinating aspects of glaciology the study of glaciers is the special wag in which these monster ice sheets move. Even more fascinating, is what a great glacier does to the face of the earth when it melts or recedes.
The footprints of the mighty glaciers of the last Ice Age are all over Canada and vast areas of the United States. We see the slaw marks from their icy fingers on hard granites. We see huge boulders carried south hundreds of miles on top of the ice and dumped as it melted. A glaciologist can also spot and identify less noticeable glacial work such as a drumlin, an esker, a kame or a kettle lake.
Their stories begin as the great glacier formed. All sorts of stones, boulders, silt and debris were frozen into the ice. A s the icy tongue pushed south, this debris was brought along with it. When at last the great mountains of ice malted, it was dumped as glacial drift far from its original home. Because the glaciers moved and melted in orderly fashion, the glacial drift was dumped in certain patterns.
Long ridges of glacial drift are called moraines. Moraines that formed at the edges of the glaciers are called drumlins. Knolls and humps of glacial drift are called kames. Flat layers of clay dumped by the glacier are called glacial till or boulder slay.
A melting glacier drips away in countless braided streams, streams in which the running water threads through and around stones end boulders. Some of these streams formed under the ice, As the.. glacial drift sank through the softening mush, the busy stream became roofed with a tunnel of debris. Long after the Ice Age has gone, the roof of the glacial stream remains as an esker, This pattern of glacial drift is a small ridge, often winding this way and that along the path of the ancient stream which no longer flows,
Sometimes a kame terrace was built up over a glacial stream. When this happened, a great boulder of ice may have bean buried in the debris. If the climate was still cold, this buried giant ice cube could last a long time long enough for the glacial drift around it to became settled,. Finally, however, it must melt. As it does so it leaves a basin' a shallow depression in the surrounding glacial drift. This basin is called a kettle. If the water shed is dust right, the kettle will fill up and become a kettle lake.