Moses Coulee Coulee, a National Natural Landmark, one of the largest examples of bars created by the Channeled Scablands outburst floods. Moses Coulee cuts into the Waterville Plateau, which lies in the northwest corner of the Columbia River Plateau. The plateau is part of the Columbia River Basalt Group, a large igneous province that lies across parts of the states of Washington, Oregon, and Idaho in the United States of America. During late Miocene and early Pliocene times, one of the largest flood basalts ever to appear on the earth's surface engulfed about 163,700 km² (63,000 mile²) of the Pacific Northwest, forming
Foster Coulee Foster Coulee Foster Coulee is a coulee in Douglas County, Washington. Like the larger Moses Coulee nearby, it was formed during the Missoula Floods at the end of the last ice age, some 14,000 years ago. Washington State Route 17 between Bridgeport, Washington and Coulee City, Washington follows East Foster Creek along much of the coulee's valley floor. East Foster Creek now flows east to west through Foster Coulee to Grand Coulee. The United States Geological Survey quadrangle map "Foster Coulee" is named for this prominent feature. Foster Coulee was formed during the Missoula Floods. The Okanogan lobe of the