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General Information Product 141

Divisions of Geologic Time (Bookmark)

By U.S. Geological Survey

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This bookmark presents information that is widely sought by educators and students. Version 3.0 of this bookmark is updated according to chapter C of U.S. Geological Survey Professional Paper 1879–1. The bookmark contains names of geologic time periods and boundary age estimates ratified by the International Commission of Stratigraphy in 2023.

First posted May 3, 2012

Revised March 29, 2024

For additional information, contact:

Youth & Education in Science (YES)
U.S. Geological Survey
National Center, Mail Stop 911
12201 Sunrise Valley Drive
Reston, VA 20192

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Suggested citation:

U.S. Geological Survey, 2012, Divisions of geologic time (ver. 3.0, March 2024): U.S. Geological Survey General Information Product 141, a bookmark,

ISSN 2332-3531 (print)

ISSN 2332–354X (online)

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