Niagara‘s past began some 450 million years ago with the formation of the Niagara escarpment. Geologists believe that where the escarpment lies today was once covered by a massive ancient sea. Rivers flowing into this sea carried sand and clay, which were deposited as sediment. The sea flourished and became rich with plant and animal life, which eventually died. Throughout the ages the sediment deposited on the seas floor was compressed and fused together to form many layers of sedimentary rocks, which began forming a new land mass. Eventually the seas water retreated leaving the land mass exposed. Pre-glacial streams and rivers were formed which began carving out the body of the plain, and over time the mass shifted and began to reshape itself into the mountainous range it is today.
When the great glacial ice age began some 23,000 years ago, the rivers and streams froze, forming massive ice sheets that were 2-3 kilometres thick. Called the Wisconsin glaciation, this enormous glacier spread quickly from eastern Canada, and would eventually cover much of Canada. For many years the ice sheet was unstoppable moving its way across vast areas and crushing and destroying anything in its path, essentially reshaping the land.
Eventually the regions climate began to slowly warm. The ice sheets began to break and move, causing enormous amounts of friction which reshaped the land, rivers, and lakes. When the glaciers retreated, water from Lake Erie began to flow over the Niagara escarpment, and Niagara Falls was born from this wonderous process some 12,000 years ago.
The Falls were originally located near Queenston, Ontario, however, the process of erosion has slowly pushed the Horseshoe Falls about 11 kilometres upstream to its present day location in the city of Niagara Falls. The Horseshoe Falls, which are approximately 2,600 feet wide, has also changed its shape through the process of erosion It has changed from a once small arch, to a horseshoe bend, to the present day gigantic inverted V. The falls will undoubtedly change again, as the current is so strong that the shape of the great cataract is continually evolving.