A landscape carved by ice, stone, and moving water
Niagara's story begins far before the modern river. Ancient seas laid down layered rocks, and the last Ice Age rearranged the Great Lakes basin. As the Wisconsin Glacier melted roughly 12,000 years ago, enormous volumes of water found a route from Lake Erie toward Lake Ontario and began cutting the Niagara Gorge.
The falls are dramatic because the rock is uneven. Hard Lockport Dolostone acts as a capstone, while softer shales below are easier for the river to undercut. As the base erodes, unsupported caprock breaks away, letting the brink retreat upstream.