Niagara Escarpment

The Niagara Escarpment is a long escarpment, or cuesta, in Canada and the United States that starts from the south shore of Lake Ontario westward, circumscribes the top of the Great Lakes Basin running from New York through Ontario, Michigan, and Wisconsin. The escarpment is the cliff over which the Niagara River plunges at Niagara Falls, for which it is named.

The escarpment is a UNESCO World Biosphere Reserve. The reserve has the oldest forest ecosystem and trees in eastern North America.^[1]

The escarpment is not a fault line but the result of unequal erosion. It is composed of an outcrop belt of the Lockport Formation of Silurian age, and is similar to the Onondaga Formation, which runs in a parallel outcrop belt just to the south, through western New York and southern Ontario. The escarpment is the most prominent of several escarpments formed in the bedrock of the Great Lakes Basin. From its easternmost point just south of Lake Ontario, the escarpment shapes in part the individual basins and landforms of Lake Ontario, Lake Huron, and Lake Michigan.

In Rochester, New York, the Genesee River flows through the city in three waterfalls over the scarp face. The escarpment thence runs westward to the Niagara River, forming a deep gorge north of Niagara Falls, which itself cascades over the scarp face. In southern Ontario, it spans the Niagara Peninsula, closely following the Lake Ontario shore through the cities of St. Catharines and Hamilton, where it takes a sharp turn north in the town of Milton toward Georgian Bay. It then follows the Georgian Bay shore northwestwards to form the spine of the Bruce Peninsula and Manitoulin Island, as well as several smaller islands in northern Lake Huron, where it turns westwards into the Upper Peninsula of northern Michigan, south of Sault Ste. Marie. It extends down the Garden Peninsula and Potawatomi Islands into Wisconsin following the Door Peninsula and then continues more inland from the western coast of Lake Michigan until ending in the southeastern corner of Dodge County.^[2]