GENERAL GEOLOGY

Detailed explanation-1: -The Great Lakes are estimated to have been formed at the end of the Last Glacial Period (the Wisconsin glaciation ended 10, 000 to 12, 000 years ago), when the Laurentide Ice Sheet receded.

Detailed explanation-2: -During the last ice age, the mile-thick Laurentide ice sheet covered most of Canada and the northern contiguous United States. The massive weight and movement of this glacier gouged out the earth to form the lake basins.

Detailed explanation-3: -A drumlin is a long, low hill of sediments deposited by a glacier. Drumlins often occur in groups. These groups are called drumlin fields.

Detailed explanation-4: -The lakes formed by glacial erosion, but geological features that formed 300 million to 1.2 billion years ago predetermined the shapes of America’s huge inland seas.

Detailed explanation-5: -Thousands of years ago, the melting mile-thick glaciers of the Wisconsin Ice Age left the North American continent a magnificent gift: five fantastic freshwater seas collectively known today as the Great Lakes-Lake Superior, Lake Huron, Lake Michigan, Lake Erie and Lake Ontario.