May 05, 2010
Reversing falls are typically caused by tidal action. They can be particularly pronounced at locations where tides are extreme, such as the Bay of Fundy in New Brunswick, Canada (above). When the Saint Johns River empties into the Bay at low tide, a small waterfall is created as the river flows over a rocky shelf. Eventually, however, as the flow tide rises above the level of the shelf (caprock), the surging seawater moves against the current of the river. The resulting “reverse” rapids can be quite tempestuous, as picture here. Photo taken on June 20, 2009.