Grand Coulee at the higher side of the flexure. Encountering the steep slope of the monocline, the new river would have cascaded off the rim, down onto a broad plain where Coulee City and Dry Falls State Park now stand. Upper Grand Coulee began as an cascade just north of Coulee City. As the rush of water eroded the surface, it steepened into a waterfall. The falls continued to erode backward (northward) creating the canyon. When the falls reached the divide into Lake Columbia, i.e., preglacial Columbia Valley, it disappeared, leaving the elongated notch. Today, the waters of the Lake Roosevelt are
Lind Coulee Archaeological Site Lind Coulee Archaeological Site The Lind Coulee Archaeological Site, also known as 45GR97, is the site of an archaeological dig near Warden, Washington. It dates to c. 11,000 cal BP. When it was first discovered in 1947, the site was seen as the first evidence of human habitation of Washington older than about 2,000–4,000 years. It was discovered by the River Basin Surveys program of the Smithsonian Institution. Richard Daugherty (then a graduate student at the University of Washington) was informed of the existence of bones and stone tools about underground, and he began visiting the site in 1948. From