How the Great Lakes Were Formed

The five Great Lakes—Superior, Michigan, Huron, Erie, and Ontario—were carved by massive glaciers during the last Ice Age, which ended about 10,000 years ago. As the ice sheets advanced, they gouged deep basins; when they retreated, meltwater filled these depressions, creating the vast freshwater system we see today. The lakes now supply drinking water, support industry, and offer recreation for millions.