Large lakes lie between 42 and 48 ° F and 77 and 92 ° F in the eastern border area between Canada, the north, and the US and the south.
Great lakes lie in the eastern border area between Canada and the United States. The group consists of five spacious lakes, shifting from the north-west to the southeast in the following order: Upper or Superior, Michigan, Huron, Iri and Ontario. They belong to the Atlantic Ocean basin. The length of the coast line is 15,450 km. Of this, the United States holds 8,700 km and Canada 6,750 km. The border between the United States and Canada passes through a considerable length across the lake. The border is demilitarized and does not pose any impediment to navigation.
In the geological-geomorphological view of the Great Lakes, they are in contact with the North American plate in the north, whose north-eastern part is embedded in the Canadian Shield and the Paleozoic layers in the south. The North American plate represents the old zone that was called by Laurence the great tectonicist and geomorphologist Edward Sis. From this name comes the name Laurentian lakes.
According to the way of setting, the Great Lakes are tectonic-glacial poligenic lakes. The erosion and the accumulation of Pleistocene glaciers, made this part of North America covered during the intense glacial phase in the form of a spacious ice field.
Tectonic movements lowered Basins of the Great Lakes(except the lakes of Iri) and represent vast cryptodepression. This means that their surfaces are above, and the deepest parts of the bottom below the sea level. Their areas lie 75 to 183 meters above the Atlantic Ocean level, and the deepest point of the bottom is 52 to 212 meters below its level.
Over time, studies of American geologists have determined the conditions under which the Great Lakes were formed and formed 1.1 to 1.2 billion years ago.
Two tectonic plates merged and created a continental rift that crossed the tectonic zone of the Great Lakes. In the Valley that was formed at that time, the basin lakes Ontario and the lakes Iri were formed, and the valley and the riverbed of the St. Lawrence. It was a tectonic phase in the formation of the Great Lakes, and in it formed lake basins.
The second phase of the formation was glacial, when the already existing basins were filled with water when the large ascelfeus pulled to the north at the end of the last ice age about 10,000 years ago, and melted. Because of the uneven intensity of the glacial the erosion that this glacier is making in the basin itself and on the sides of the basin, has formed the islands.