Niagara Falls were formed when glaciers receded at the end of the Wisconsin glaciation (the last ice age), and water from the newly formed Great Lakes carved a path through the Niagara Escarpment en route to the Atlantic Ocean.
Niagara Falls was formed when melting glaciers started to form large freshwater lakes known as the Great Lakes. The water in the Lake Erie ran downhill to the Lake Ontario where it formed a river. The river then crossed a ridge called the Niagara escarpment. The particular area where the river fells over the cliffs of the escarpment was then referred to as Niagara Falls.