Nonmarine carbonaceous rocks, including shales, coal, and peat, were tested at about 3 localities in California, Idaho, Nevada, Oregon, Utah, and Washington. Rocks ranging in age from Carboniferous to Quaternary were examine, although the principal attention was given middle and late Tertiary lignites of the northern part of the Great Basin. Most carbonaceous rocks examined contained essentially no uranium, but lignitic shales in the Goose Creek district, Idaho, a thin carbonaceous shale near Hagerman, Idaho, and a small peat deposit in Davis County, Utah contained more than 0.003 percent uranium.