This elevated ridge on the right is the Niagara Escarpment. Beginning at the Niagara River Gorge, it extends north, through Ontario, 440 miles, 725 kilometers to Georgian Bay, Tobermary, and Manitoulin Island, the world’s largest freshwater island. Geologists say 430 million years ago much of central North America was covered in the shallow tropical lake. The sediments deposited from that composing the ridge were compressed into a hard limestone called Dolomite., more resistant to erosion than the surrounding land. So the surface of the ridge is the exposed floor of the ancient tropical sea. In 1990, the United Nations declared The Niagara Escarpment a World Biosphere Reserve. One of Earth’s older natural formations.