USA HISTORY

Detailed explanation-1: -About 2 percent of all the water on Earth is frozen in glaciers. Glaciers can range in age from a couple hundred to thousands of years old. Most glaciers today are remnants of the massive ice sheets that covered Earth during the Ice Age. The Ice Age ended more than 10, 000 years ago.

Detailed explanation-2: -During vast ice ages millions of years ago, sheets of glaciers stretched from the poles almost to the equator, covering the Earth in a frozen skin.

Detailed explanation-3: -During the Ice Age temperature were only 5 to 10 degrees colder than today. As recently as 20, 000 years ago, glaciers hundreds and thousands of feet thick covered all of Canada, much of the United States ad most of northwestern Europe. There was less glaciation over Russia.

Detailed explanation-4: -The huge glaciers changed air flows and weather patterns and turned previously dry areas into wet areas, leading to the formation of the lakes. The glaciers were so heavy that they caused isostatic depression, which is the sinking of the earth’s crust due to pressure from a heavy weight.