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 Dam residents were relocated. The Anti-Speculation Act was passed in 1937, limiting the amount of land farmers could own to prevent inflated prices. The government appraised the land and offered to purchase it from the affected residents. Many refused to accept the offers, and Reclamation filed condemnation suits. Members of the Colville Confederated and Spokane tribes who had settlements within the reservoir zone were also resettled. The Acquisition of Indian Lands for Grand Coulee Dam Act of , 1940, allowed the Secretary of the Interior to acquire land on the Colville and Spokane Reservations, eventually accounting for . By 1942, all