Knox Group (Safford, 1869). Dolostone, limestone, and sandstone. Dolostone, light- to medium-gray, very-fine- to fine-grained, locally with pink streaks in the upper part; and very-light-gray to dark-gray and brownish-gray, medium- to coarse-grained, locally argillaceous dolostone near the base of the unit; greenish-gray shale partings locally present; chert is abundant in some parts of the unit. Limestone, blue gray to dark-blue-gray, very-fine- to coarse-grained, locally sandy. Sandstone, gray to brown, fine- to medium-grained. Limestone is dominant in the eastern thrust belts. The Knox Group ranges from 2000 feet in Southwest Virginia to 3560 feet in thickness to the east in Washington County (Bartlett and Webb, 1971). The Knox includes the Mascot, Kingsport, Chepultepec, and Copper Ridge Dolomites and the Maynardville Formation.