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Episodes 1989; 12(1): 3-5

Published online March 1, 1989


Copyright © International Union of Geological Sciences.

A Synopsis of Numerical Time Scales 1917-1986

Manfred Menning

ZIPE, Telegrafenberg, Potsdam, Post Potsdam, D.D.R. 1561

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


This review accompanies a multicoloured synoptic chart (inserted loose in this issue) comparing some 30 complete and partial geochronological time scales for the Phanerozoic and published over a 70 year period to 1986. Provided for Episodes readers by the Central Institute for Physics of the Earth in Potsdam, East Germany, the chart illustrates the evolution of the geological time scale since the advent of rediometric dating. It is a salutary experience to see how close the most recent scales are to Barrell's 1917 estimates, and to gauge the extent of "fine-tuning" that has taken place since Arthur Holmes' 1959 scale. This chart provides a convenient companion to the 1989 IUGS Global Stratigraphic Chart, which will be circulated in a forthcoming issue of Episodes. (Ed.)