Forming long before man roamed the earth and still today slowly continuing its process of reformation, Niagara Falls has become a worldwide tourist site and geological amazement.
The continued and present process of reformation is contributed to an annual freezing and re-thawing of the rivers water. This event allows the reformation and eventual wearing away of the rocks beneath the surface, that along with continued erosion and periodic falling of large rock formations have slowly moved the falls further upstream. The occurrences however have slowed tremendously due to human interaction and influence. The amount of water allowed to flow and remain has been greatly reduced for the purpose of hydroelectric power as well as work performed to the falls to further preserve them.
Roughly 600 million years ago much of North America was covered by a shallow sea resting upon ancient and already formed Pre-Cambrian rock. Over the next 100-200 million years erosion in the form of wind, rain and waves dismantled ground rocks into a soft powder, which accumulated layer after layer at the sea bottom. Year after year these layers of soft dismantled powder continued to collect on top of the much harder Pre-Cambrian rock already in existence and settled at the sea floor.
With time the Earth began to redefine itself. Mountains formed, bodies of water were created and erased and river systems found new patters and directions to flow. These river systems began to collide and form enlarged muddy deltas that later cemented and created the purple-red shale and sandy ledge-forming rocks of Niagara Gorge.
With time weather patterns changed and about 425 million years ago tropical water and warm temperatures gave life to many water reef-building creatures. As time passed and the creatures died their bodies and homes were absorbed and combined with a rain of lime dust at the bottom of the sea floor creating the caprock of the Niagara Escarpments.