These pictures are from when they diverted the flow of water over the American side of the falls to do delay the gradual erosion on the falls.
It's taken 41 years, but a previously unseen set of photos of the mighty Niagara Falls reduced to nothing more than a barren cliff-top have finally surfaced.
The stark images reveal North America's iconic - and most powerful - waterfall to be almost as dry as a desert.
In June 1969, U.S. engineers diverted the flow of the Niagara River away from the American side of the falls for several months.
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