Since the late 1800's, the U.S. Geological Survey has been responsible for maintaining a lexicon of geologic names for the Nation. The published lexicons (see below) include brief definitions for each unit (e.g., the lithology, thickness, age, underlying and overlying formations, and type locality). These were published at irregular intervals.

Copies of these USGS publications are provided below, for quick reference. [For downloadable files exceeding 10 MB, the filesize is noted.] Statewide and regional correlation charts, lexicons, and other stratigraphic resources are provided here.

Lexicons

Years addressed by publication	Description	USGS Publication
1902 and earlier	List of geologic names	Bulletin 191 (29MB)
1936 and earlier	New and revised names	Bulletin 896 — Part 1 (A-L) (68MB), Part 2 (M-Z) (65MB)
1936 – 1955	List of new names	Bulletin 1056-A
1959 and earlier	List of names	Bulletin 1056-B
1936 – 1960	New and revised names	Bulletin 1200 — Part 1 (A-F) (85MB),   Part 2 (G-O) (85MB), Part 3 (P-Z) (86MB)
1961 – 1967	New names	Bulletin 1350 (66MB)
1968 – 1975	New names	Bulletin 1520 (19MB)
1975 and earlier	List of names	Bulletin 1535 (25MB)
1976 – 1980	New names	Bulletin 1564 (12MB)
1981 – 1985	New names	Bulletin 1565 (27MB)

Changes in stratigraphic nomenclature adopted by the USGS

Year addressed by publication	USGS Publication
1952 - 1963	U.S. Geologic Names Committee, Changes in geologic nomenclature (unpublished): U.S. Geological Survey. The Committee's copy is available for viewing.
1963	Cohee, G.V., and West, W.S., 1965, U.S. Geological Survey Bulletin 1194-A, 34 p.
1964	Cohee, G.V., and West, W.S., 1965, U.S. Geological Survey Bulletin 1224-A, 77 p.
1965	Cohee, G.V., and West, W.S., 1966, U.S. Geological Survey Bulletin 1244-A, 60 p.
1966	Cohee, G.V., West, W.S., and Wilkie, L.C., 1967, U.S. Geological Survey Bulletin 1254-A, 43 p.
1967	Cohee, G.V., Bates, R.G., and Wright, W.B., 1969, U.S. Geological Survey Bulletin 1274-A, 59 p.
1968	Cohee, G.V., Bates, R.G., and Wright, W.B., 1970, U.S. Geological Survey Bulletin 1294-A, 55 p.
1969	Cohee, G.V., Bates, R.G., and Wright, W.B., 1970, U.S. Geological Survey Bulletin 1324-A, 41 p.
1970	Cohee, G.V., Bates, R.G., and Wright, W.B., 1971, U.S. Geological Survey Bulletin 1354-A, 38 p.
1971	Cohee, G.V., and Wright, W.B., 1972, U.S. Geological Survey Bulletin 1372-A, 28 p.
1972	Cohee, G.V., and Wright, W.B., 1974, U.S. Geological Survey Bulletin 1394-A, 93 p.
1973	Cohee, G.V., and Wright, W.B., 1975, U.S. Geological Survey Bulletin 1395-A, 68 p.
1974	Cohee, G.V., and Wright, W.B., 1975, U.S. Geological Survey Bulletin 1405-A, 36 p.
1975	Cohee, G.V., and Wright, W.B., 1976, U.S. Geological Survey Bulletin 1422-A, 84 p.
1976	Sohl, N.F., and Wright, W.B., 1977, U.S. Geological Survey Bulletin 1435-A, 151 p.
1977	Sohl, N.F., and Wright, W.B., 1978, U.S. Geological Survey Bulletin 1457-A, 136 p.
1978	Sohl, N.F., and Wright, W.B., 1979, U.S. Geological Survey Bulletin 1482-A, 91 p.
1979	Sohl, N.F., and Wright, W.B., 1980, U.S. Geological Survey Bulletin 1502-A, 138 p.