How was it formed?

The Niagara Escarpment has origins dating back into geological history some 430 to 450 million years, a time when the area lay under a shallow warm sea. This sea lay in a depression of the earth's crust, the centre of which is now the State of Michigan. Now geologically known as the Michigan Basin, the outer rim of this massive saucer-shaped feature governs the location of the Niagara Escarpment. In the shape of a gigantic horseshoe. The Escarpment can be traced from near Rochester, New York, south of Lake Ontario to Hamilton, north to Tobermory on the Bruce Peninsula, beneath the waters of Lake Huron to appear again on Manitoulin Island, across northern Michigan and down the west side of Lake Michigan into the State of Wisconsin.

The Escarpment formed over millions of years through the differential erosion by weather and streams of rocks of different hardnesses. The Niagara Escarpment has a caprock of dolostone which is more resistant and overlies weaker, more easily eroded shale rocks. Through time the soft rocks weather and erode away by the action of streams. The gradual removal of the soft rocks undercuts the resistant caprock, leaving it standing as a cliff - the escarpment. The erosional process is most readily seen at Niagara Falls, where the river has speeded the process. The Niagara Escarpment is not formed by faulting. There is no displacement of the rock layers at the Escarpment, as shown by study or rock exposures and drillholes. Additional resistant rock layers make more than one escarpment in some places. Also, in some places thick glacial deposits conceal the Niagara Escarpment, such as north of Georgetown, but it continues underground and reappears farther north.