The rocks in the Niagara Escarpment were deposited during the Ordovician and Silurian periods of Earth’s history, about 450 to 430 million years ago. At that time, this part of North America was located about 20 degrees south of the equator. Shallow tropical seas, like those in the Bahamas today, covered the region. The rocks started as layers of mud on the ancient seafloor. Numerous nearby catastrophic upheavals, along with changing drainage patterns deposited layer after layer of mud and debris to form this sedimentary rock. Evidence of these shallow seas exists in the form of fossils and reef formations.
To illustrate the massive changes occurring during the escarpment’s creation, consider that at one time, the Great Lakes system used to exit from a location on the east side of what is now the Georgian Bay, not the current St. Lawrence Seaway route. In fact, evidence of an ancient massive waterfall exists between the tip of the Bruce Peninsula and Flowerpot Island which plunged some 300 feet. Further connections have been made between ancient First Nation stories and current-day geologic/hydrologic research by the Canadian Government.