Grand Coulee of the continental shelf. The web-like formation can be seen from space. Mountains of gravel as tall as 40-story buildings were left behind; boulders the size of small houses and weighing many tons were strewn about the landscape. Grooves in the exposed granite bedrock are still visible in the area from the movement of glaciers, and numerous erratics are found in the elevated areas to the northwest of the coulee. Early theories suggested that glaciers diverted the Columbia River into what became the Grand Coulee and that normal flows caused the erosion observed. In 1910 Joseph T. Pardee described a
Grand Coulee pumped from the Grand Coulee Dam, into Banks Lake to act as an Equalizing Reservoir and irrigation water source. Evidence of the waterfalls includes a plunge basin where the falls began, immediately south of Coulee City. It contains at least of gravel lower than the open flooring of the land. The river above the falls was shallow and much wider than the gorge. Thus, it wrapped around the lip of the main falls creating lateral falls. These flowed until the recession of the main falls denied them water. Northrup Canyon in Steamboat Rock State Park, contains a dry cataract as