USGS Geolex

The Geolex is part of the United States Geological Survey (USGS) National Geologic Map Database, and covers lithostratigraphy of the United States. Data are sourced from the USGS and State Geological Surveys. Many collections use this as an authoritative source for lithostratigraphy in the US.

TIP This resource can be used to verify a lithostratigraphic unit (e.g., the age of the unit, spelling, geographic extent, etc). It also links to publications about the unit which can be helpful for various verification tasks.

Coverage and gaps

Lithostratigraphy of the United States. Anecdotally, some lithostratigraphic units do not have the most up to date geologic ages associated.

Data reuse

It may be useful to reference individual lithostratigraphic concepts in the Geolex. Users can do so by citing the appropriate page, e.g. for the Ladd Formation. Although lithostratigraphic concepts are associated with an identifer in the Geolex URL (e.g. “5841” for the Ladd Formation), it is unclear whether or not these identifiers are stable so that full URL should be used.