Dry Falls is a , 5.5 km in width , scalloped precipice with four major alcoves , in central Washington scablands . This cataract complex is on the opposite side of the Upper Grand Coulee from the Columbia River , and at the head of the Lower Grand Coulee , northern end of Lenore Canyon . According to the current geological model , catastrophic flooding channeled water at 65 miles per hour through the Upper Grand Coulee and over this rock face at the end of the last ice age . It is estimated that the falls were five times the width of Niagara , with ten times the flow of all the current rivers in the world combined
catastrophic flooding
Missoula Floods
Dry Falls