Grand Coulee Columbia Rivers pathway and onto the southern plateau creating an ice dam. This dam backed up the waters of the Columbia into Glacial Lake Columbia and later during the Missoula Floods forced those waters into eastern Washington, creating the Scablands. The river at Grand Coulee found no existing valley and thus forged its own pathway across the divide, creating the Upper Coulee. The plateau is not level, but is marked with wrinkles and upfolds of the basalt. The diverted waters of the Columbia, encountered the monoclinal flexure, a steep warping up of toward the northwest. Lake Columbia topped the ridge
Etzikom Coulee of at its origin east of Stirling Lake (to which it is connected by the Sluice Gate Channel) to an elevation of at its mouth at Pakowki Lake, over a length of more than . The coulee builds a canyon up to deep. Etzikom Coulee Etzikom Coulee is a coulee located in Southern Alberta, Canada. The waterway was formed as a glacial spillway channel at the end of the last ice age. The Etzikom Coulee begins northeast of the town of Stirling, and makes its way southeast of the Hamlet of Wrentham, after that it passes by the Hamlet of