This series contains multicolor or black-and-white geologic maps that show bedrock geology, stratigraphy, and structural relations of selected coal resource areas of the Nation. The numbering of these maps began in 1950; a few unnumbered maps were produced as early as 1935.
- C 139-A
- Roberts, S.B., 1991, Subsurface cross section showing coal beds in the Sagavanirktok Formation, vicinity of Prudhoe Bay, east-central North Slope, Alaska: U.S. Geological Survey Coal Investigations Map 139-A, 1 sheet, scale 1:517,000.
- C 51
- Barnes, F.F., 1962, Topographic and geologic map of the Knob Creek area of the Wishbone Hill district, Matanuska coal field, Alaska: U.S. Geological Survey Coal Investigations Map 51, 1 p., 1 sheet, scale 1:6,000.