Withrow Moraine and Jameson Lake Drumlin Field erosion resulting from the Missoula Floods, which laid bare many layers of the basalt flows on the edges of the plateau at Grand Coulee and Moses Coulee. Two million years ago the Pleistocene epoch began and Ice age glaciers invaded the area. They scoured the Columbia River Plateau, reaching as far south as the middle of the Waterville Plateau highlands above the Grand Coulee and south to the head of Moses Coulee. In some areas north of the Grand Coulee they were as much as 3 km (10000 feet) thick. Grooves in the exposed granite bedrock are still visible in
Grand Coulee Dam Clapp were pumpers, while many influential businessmen in Spokane associated with the Washington Water and Power Company (WWPC) were staunch ditchers. The pumpers argued that hydroelectricity from the dam could cover costs and claimed the ditchers sought to maintain a monopoly on electric power. The ditchers took several steps to ensure support for their proposals. In 1921, WWPC secured a preliminary permit to build a dam at Kettle Falls, about upstream from the Grand Coulee. If built, the Kettle Falls Dam would have lain in the path of the Grand Coulee Dam's reservoir, essentially blocking its construction. WWPC planted rumors