Because of the volume of water flowing over Niagara Falls, it is near impossible for them to completely freeze over. That being said, they can appear to be frozen over. This is usually caused by ice upriver of the Falls slowing the water, allowing it to create icicles at the edge of the Falls, and by the mist freezing in big “icebergs” at the base of the Falls. However, there is water, usually at least a trickle, that is still flowing under the ice. Up until the polar vortexes of 2014 and 2015, the American Falls has “Frozen over” 6 times, in 1883, 1896, 1904, 1909, 1936 and 1947.There was one time, March 29 30, 1848, that the Canadian Falls also stopped. Some started walking out on the rock river bed on foot and horseback, looking for lost treasure. Others gathered in churches to pray, thinking “Maybe it's the end of the world”. What could stop the powerful river? The ice was breaking up on Lake Erie, strong winds blew the ice fields to the mouth of the river, blocking it like a dam. After 30 hours, it burst through with the high crest and mighty roar.