|The Niagara Whirlpool|
|Location||North of the cities of Niagara Falls, ON and Niagara Falls, NY|
|Average depth||125 feet (38 m)|
The Niagara Whirlpool is a natural whirlpool along the Niagara River located along the U.S.-Canadian border between New York and Ontario. The whirlpool is located in the Niagara Gorge, downstream from Niagara Falls. The whirlpool's greatest depth is 125 feet (38 m).
Formation of whirlpool
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 [9 m•s-1]), 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.
There are two state/provincial parks located alongside the whirlpool. On the U.S. side is the Whirlpool State Park. On the Canadian side is the Niagara Glen Nature Reserve. The Whirlpool Aero Car, which traverses the river above the whirlpool, is also located on the Canadian side.
- "Whirlpool State Park - Niagara Falls, New York". Nyfalls.com. 1935-09-13. Retrieved 2011-08-20.
- "Niagara Whirlpool (FAQ)". Nyfalls.com. Retrieved 2011-08-20.
- Gifford, Clive (2005). Weathering and Erosion. Evans Brothers. p. 23. ISBN 978-0-237-52744-0.
- "Niagara Falls Geology Facts & Figures". Niagaraparks.com. Retrieved 21 August 2011.