The Great Lakes are five freshwater lakes located in the upper Northeast of North America, bordering with Canada. They are the location of large fishing industries, tourist areas, and the largest centralized collection of the Earth's surface fresh water.
The Great Lakes began formation about 1.2 billion years ago when Tectonic Plates under the Earth's surface split apart, creating a rift where rock and dirt settled, allowing water to begin collecting. Over the next billion years, more plates shifted and more fissures developed, and since the Glacial Age was ending, a great deal of fresh water collected as the glaciers covering North American and Canada melted.
The official formation of the Great Lakes started around 8,000 B.C.E., when the Laurentide Ice Sheet began to recede. Previous glacial activity had cut deep fissures into the ground, and these filled with water flowing down from the ice sheet as it melted. Gravity played two roles here: the first was the weight of the glaciers on the Earth's surface, where the ground was compressed and divided by the slow movement of the ice; the second was on the melting water, which could not disperse over the ground back to the ocean because of the low lake beds.