In central Washington, on the opposite side of the Grand Coulee from the Columbia River, resides a three and a half mile crescent-shaped precipice known as Dry Falls. Ten times the size of Niagara, Dry Falls is thought to be the greatest known waterfall that ever existed. Geologists speculate that during the last ice age catastrophic flooding channeled water at 65 miles per hour through the Grand Coulee and over this 400-foot rock face. At this time, it is estimated that the flow of the falls was ten times greater than the current flow of all the rivers in the world combined.