The Creation of Niagara Falls

By Teri Champigny

Niagara Falls is estimated to be more than 10,000 years old, and is a direct result of the last ice age. The formation of the falls, however, started as far back as 18,000 years when ice sheets covered southern Ontario. These ice sheets were approximately 6000 feet thick!

The ice sheets moved further south over time, carving out the basins of what we now know as the Great Lakes. While this was happing, further north the ice was melting, and the melt waters of course eventually filled these basins.

Geologists estimate that the ice melted in what we know as the Niagara Peninsula about 12,500 years ago. As that water moved north, it flowed into a basin that we now call Lake Erie, as well as Lake Ontario and the Niagara River.

The water continued to flow towards the Atlantic through the St. Lawrence River. At one time, water spilled into Lake Ontario from Lake Erie in five different locations. Today, that has been reduced to one spillway at Queenston-Lewiston.

The actual falls themselves were created by a constant advancement and retreat of the ice. When the pressure from the ice was released, the land would rebound. The process would become interrupted, causing the melt water to go through northern Ontario. The falls were not restored to their full power until the waters were once again rerouted through Southern Ontario, about 5500 years ago.

The falls were not falls in the beginning, however. They were originally a violent, fast moving rapid. During the phase where the water had rerouted itself through Southern Ontario, it connected with a very old river that had been sealed during the ice age. When it was finished, in what many believe to be just a few weeks, it had created a 90 degree turn in the river. Today, we call this the Whirlpool, and in the United States, this is the largest collection of standing waves, called the Whirlpool Rapids.

After that miraculous creation, the falls continued on from the Whirlpool Bridge, making its way through solid rock. But erosion was also present, even then, in the form of Cavitation. Cavitation is a type of erosion that happens at most waterfalls. The water must move at a high enough speed to create bubbles close to rock to have an impact on it.

The water has increased power because it gains speed as it falls over, which of course causes a breakdown of internal pressure. When this happens, it creates air bubbles. These air bubbles are destroyed when they hit the bottom and the water falls on them. Think of very high pressured air. When the air bubbles are destroyed, they basically put a great deal of pressure on the rocks that surround them.

When you are viewing the falls, make sure that you consider how the last ice age gave you the beauty that you are lucky enough to behold. This entire area was once covered by pure ice sheets. Today, it is a place of astounding beauty that brings millions of visitors each year.