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Divisions of Geologic Time - Major Chronostratigraphic and Geochronologic Units

Fact Sheet 2007-3015

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Abstract

Introduction 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 calibrated in years (Harland and others, 1982). Over the years, the development of new dating methods and refinement of previous ones have stimulated revisions to geologic time scales. Since the mid-1990s, geologists from the U.S. Geological Survey (USGS), State geological surveys, academia, and other organizations have sought a consistent time scale to be used in communicating ages of geologic units in the United States. Many international debates have occurred over names and boundaries of units, and various time scales have been used by the geoscience community.

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:
2007-3015
Edition:
-
Year Published:
2007
Language:
ENGLISH
Publisher:
Geological Survey (U.S.)
Contributing office(s):
U.S. Geological Survey
Description:
2 p.