The Niagara River sends 6 million cubic feet (169,901 cubic m) of water over Niagara Falls every minute. However, in 1969, the torrent of the American Falls was reduced to a mere trickle. For five months, engineers diverted the water to Horseshoe Falls on the Canadian side while they removed loose rock at the base and shored up other areas, in an attempt to delay the onset of erosion. At the end of the project, the engineers blew up their temporary 600-foot-tall (183 m) dam and the thunderous wall of water resumed its rush over the falls.
A natural wonder created by glacial retreat: