Dry Falls is a vast dry waterfall escarpment in central Washington, formed near the end of the last glaciation by repeated Ice Age floods. In the accepted model, an ice dam on the Clark Fork River created Lake Missoula, while ice also blocked the Columbia River to form Glacial Lake Columbia. When the Missoula dam failed, floodwater spilled into Glacial Lake Columbia and raced down the Grand Coulee, likely many times. At Dry Falls, the torrent plunged over a 400-foot rock face at great speed, carving a 3.5-mile-long cliff and large plunge pools before the Columbia returned to its normal course and the falls ran dry.