THE U.S. GEOLOGIC NAMES LEXICON (GEOLEX) – A RESEARCH TOOL FOR GEOARCHAEOLOGISTS

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.

Geologic descriptions in GEOLEX are designed as a quick guide to the nature of the geologic unit and to significant publications. Although intended for use by field geologists, we suggest that the lexicon's lithologic, biostratigraphic, geochemical, and isotopic information can be a research tool for archaeologists as well.