VIDEO: Niagara Falls will eventually erode away but we’ll never see it happen


Published May 25, 2022 at 10:05 am

Once upon a time, the Horseshoe Falls, top centre, and the American Falls to the left, were one big connected waterfall.

Where Niagara Falls is located now is not where it started.

Over 12,000 years ago, it’s estimated Niagara Falls was located where the Queenston-Lewiston Bridge is currently sitting. That’s 11.4 kilometers or 7.1 miles down the river where Niagara-on-the-Lake is now situated.

Yes, at one time, Niagara Falls was Niagara-on-the-Lake Falls except of course, both were uncharted, uninhabited lands and not very much in need of a name at the time, other than “forest.”

So how has Niagara Falls been moving backwards from Lake Ontario towards Lake Erie over those many centuries? Simple erosion.

Back in 1841, Charles Lyell, a British scientist and one of the fathers of modern geology ventured to Niagara Falls. From observations of the various rocks both at the Falls and along the Niagara River, Lyell was able to illustrate that the cascading waters had eroded the gorge from the edge of the escarpment at Queenston-Lewiston to its present location.

So why hasn’t Niagara Falls eroded further up the Niagara Gorge towards Lake Erie so that’s it’s no longer in immediate view of either Niagara Falls, Ontario or Niagara Falls, New York?

Experts believe there’s two reasons. The first is that the limestone cap rock, which the water is currently flowing over, is more resistant to erosion.

This limestone layer begins approximately a half of a kilometre (third of a mile) north of the Rainbow Bridge. As the Falls continue to erode southward, the erosion rate will increase when it reaches Navy Island when the Falls will reach a softer layer of rock.

But what’s really slowing down the erosion is the creation of the hydro-electricity plants on the two shorelines. Due to their water diversion from the river through their plants, they have significantly slowed the rate of the flow over the falls.

Some 800 years ago, Niagara Falls existed as a single water fall. The separation of the waterfall into the two waterfalls, the smaller American and the much larger Horseshoe Falls is relatively new in its 12,000 year history. Next to the American Falls is the even smaller Bridal Veil Falls, which most people tend to lump into the American Falls as one single waterfall.

As well, the curved shape of the Horseshoe Falls slows down erosion. The crest of the Falls was straight until roughly 1775 and located north of the present-day Rainbow Bridge. As the middle started to erode and recede, the sides remained, creating the horseshoe shape.

The shape of the crest line determines its stability. The uniform Horseshoe shape of the crest line of the Falls provides greater stability. The deepest plunge pools are carved out when the crest line of the Falls is relatively stable.

As the water flow and erosion slowed down due to the limestone cap rock, Goat Island on the American side emerged, split the flow into two directions. One tenth of the Niagara River flow goes to the American side while 90 per cent flows over the Horseshoe Falls on the Canadian side.

The difference is basically this – 3,160 tons of water flows over Niagara Falls every second. This accounts for 75,750 gallons (344,366 litres) of water per second over the American and Bridal Veil Falls and 681,750 gallons (3 million litres) per second over the Horseshoe Falls.

The water falls at 32 feet per second over the Falls, hitting the base of the Falls with 280 tons of force at the American and Bridal Veil Falls and 2,509 tons of force at the Horseshoe Falls.

So will Niagara Falls eventually erode so far back that it sits at the edge of Lake Erie?

Scientists estimate the world’s second largest waterfall will disappear into Lake Erie 23,000 years from now. The reasoning behind that theory is based on the fact that it took 12,000 years to shift from what’s now Niagara-on-the-Lake to Niagara Falls.

They figure it will likely take twice that because it’s 217 km (134 miles) between the lake and the falls. However, once erosion gets past the limestone cap rock, it will speed up considerably.

Here, an expert named Kent Hovind discusses erosion of Niagara Falls.

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