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Niagara Falls
August, 2014
American Falls
It is estimated that the whirlpool formed approximately 4,200 years ago by the upstream erosion of the Niagara Escarpment by the Niagara River. Niagara Falls is
located along the boundary of the Niagara Escarpment and has been "retreating" upstream since its formation. During this normally slow process, the retreating
falls intersected with an ancient pre-glacial river bed inside Saint David's Buried Gorge. During the retreat of ice from the Wisconsinan glaciation of the last
glacial period, the gorge was filled with loose sediment and rock. When the falls intersected with this buried gorge, the river quickly washed away the filled-in silt
and rocks. The ancient buried gorge was nearly perpendicular to the Niagara River. This sharp and sudden change in direction of water flow, coupled with the rapid
flow of water exiting the Niagara Gorge (speeds as high as 30 feet per second, resulted in turbulent swirling of the river. Further erosion of the harder rock has
resulted in a rounded basin that extends just to the side of the actual river's course.
The whirlpool naturally spins in a counterclockwise motion during normal flow. When more water from the river is diverted to the surrounding hydroelectric power
plants, however, the flow often reverses.
American Falls
Canadian Falls