Late Pleistocene outburst megafloods, mostly from glacial Lake Missoula, hydraulically ponded behind downstream constrictions in the Columbia River southeastern Washington State, USA. Optically stimulated luminescence (OSL) ages for flood deposits Coyote Canyon Mammoth Site, located a high (315–320 m asl) distal portion of transient lake, indicate that at least seven floods enough to inundate a...