THE U.S. GEOLOGIC NAMES LEXICON (GEOLEX) – CORRELATING GEOLOGIC AND COMMERCIAL NAMES

In the late 1800's, the USGS, under the leadership of Director John Wesley Powell, began a systematic mapping program that produced the Geologic Atlas of the United States folios. Recognizing the need to provide a consistent set of geologic maps, he formed committees to develop standards for cartography, principles of rock and sediment classification and nomenclature, and a geological time scale. Essential to these standards and to the Atlas series was a catalog of geologic names of the U.S.

The catalog of geologic names remains essential to this day, both to the science and to preparation of the National Geologic Map Database (NGMDB, http://ngmdb.usgs.gov); today, the U.S. Geologic Names Lexicon (GEOLEX) is a component of the NGMDB. It contains ~16,000 geologic units, and provides original and revised definitions, type localities, geologic ages, geographic extent, variations in geologic name usage, and publication synopses. Information has been compiled mostly from formal reports and maps published since 1836, emphasizing outcrop-level descriptions, age determinations, and relationships to other geologic units.

Many geologic units are economically important, and in the commercial building stone and mining industries some of these have been informally named (for example, the geologic unit name Salem Limestone is commonly referred to as the Indiana Limestone). In order to increase understanding of the nature and geographic extent of a geologic unit, and to reduce ambiguity, it would be helpful to correlate the geologic name to the name(s) used by industry. The NGMDB project would like to assist in this process by identifying in GEOLEX the common name(s) applied to a geologic unit, and welcomes suggestions and information on the subject.