Divisions of geologic time-major chronostratigraphic and geochronologic units

Effective communication in the geosciences requires consistent uses of stratigraphic nomenclature, especially divisions of geologic time. A geologic time scale is composed of standard stratigraphic divisions based on rock sequences and is calibrated in years. Over the years, the development of new dating methods and the refinement of previous methods have stimulated revisions to geologic time scales. Advances in stratigraphy and geochronology require that any time scale be periodically updated. Therefore, Divisions of Geologic Time, which shows the major chronostratigraphic (position) and geochronologic (time) units, is intended to be a dynamic resource that will be modified to include accepted changes of unit names and boundary age estimates. This fact sheet is a modification of USGS Fact Sheet 2007-3015 by the U.S. Geological Survey Geologic Names Committee.

Suggested Citation

U.S. Geological Survey Geologic Names Committee, 2010, Divisions of geologic time-major chronostratigraphic and geochronologic units: U.S. Geological Survey Fact Sheet 2010-3059, 2 p., https://doi.org/10.3133/fs20103059.

ISSN: 2327-6932 (online)

Additional publication details
Publication type	Report
Publication Subtype	USGS Numbered Series
Title	Divisions of geologic time-major chronostratigraphic and geochronologic units
Series title	Fact Sheet
Series number	2010-3059
DOI	10.3133/fs20103059
Year Published	2010
Language	English
Publisher	U.S. Geological Survey
Contributing office(s)	Geologic Names Committee
Description	2 p.
Online Only (Y/N)	Y
Additional Online Files (Y/N)	N