Great Lakes

the chain of lakes along the border between the eastern United States and Canada. They contain over 5,000 cubic miles of water; they have a combined surface area of 86,000 square miles; and constitute the greatest body of fresh water in the world. At one time, during the existence of a huge ice sheet, a glacier filled the present gorge of the St. Lawrence and dammed back the water. The Great Lakes then formed one sheet of water, a vast inland lake, the borders of which may be traced in the United States and Canada. The waters were discharged by way of the Mohawk Valley and the Hudson. The old outlet started near Rome, New York, on the southern shore of Lake Ontario. The present shore line is about 4,000 miles in length. The total water-shed comprises about 260,000 square miles. The depressions in which the lakes lie were caused by a settling of the earth's crust it is thought, due to the weight of glacial ice. By treaty agreement neither the Dominion of Canada nor the United States may maintain war vessels on the Great Lakes, nor erect fortifications on the shores. By permission of Canada the United States now maintains fifteen vessels as training ships on the Lakes. These ships carry six hundred men and seventy guns. See Superior; Ontario; Michigan; Huron; Erie; Sault Ste. Marie; Niagara, etc.