GeoWhen Database  

Introduction

Geologic Timeline
(No Stages)

Geologic Timeline
(With Stages)

A-Z Stage List

Regional Information

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Introduction

Welcome to the GeoWhen Database, an attempt to sort out the mess that man has made of the geologic timescale.  This project aims to reconcile the international stratigraphic standards with many of the regional and archaic naming schemes that appear in the literature.  In the process, the most recent ICS time scale has been combined with information on the estimated placement and length of other stages in order to put approximate dates on all of the stratigraphic intervals recorded here.  In this way, we have sought to reconcile all of the various geologic time scales into a single self-consistent whole.

What is this information based on?
The central stratigraphic classification and dates are based on the 2004 time scale endorsed by the International Commission on Stratigraphy (ICS) and documented in Gradstein, Ogg, Smith, et al., A Geologic Time Scale 2004, forthcoming from Cambridge University Press.  This has been augmented by consulting a number of other reference works, including:

  • Harland et al., A Geologic time scale, Cambridge University Press, 1982.
  • Harland et al., A Geologic time scale 1989, Cambridge University Press, 1990.
  • Gradstein and Ogg, "A Phanerozoic time scale", Episodes, v.19, no.1&2, 1996.
  • Haq and Eysinga, Geological Time Table, Elsevier Science, 1998.
  • Palmer and Geissman, 1999 Geologic Time Scale, Geological Society of America, 1999.
  • An Atlas of Life on Earth, Barnes and Noble Books, 2001.
  • Paleobiology Database Conversion Tables
  • www.Palaeos.com
  • and others...

The information provided by these sources on regional and archaic stage nomenclatures has been correlated with the international standards while taking care to preserve stage ordering and common boundaries.  Future versions of this database will be augmented with direct input from the ICS working groups.

How reliable are the dates?
Dates are provided for all boundaries, but they clearly vary in accuracy and reliability.  The best available dates have been listed with reference and error information.  Most of the others represent some form of approximation.  This may amount to either copying the approximate values given in other reference works or performing interpolations based on estimates of the length and position of a particular stage.  In doing this, it is assumed that the boundaries and relations between various stages are generally better known than their exact ages.  It should also be acknowledged that for many of the more obscure regional and faunal stages the exact boundaries are not only poorly known, but historically have been poorly defined.  For these reasons, whenever precise dates are needed, it is recommended that work be done in reference to the ICS time scale.

I found an error or would like to make a contribution, what should I do?
In any project of this size, it is natural to expect that some errors will exist, and that many of the relations and dates will improve with further study.  If you find something that needs improvement, particularly missing stages or stages out of order, feel free to contact Robert Rohde at geowhen@robertrohde.com.  It is greatly preferred that you provide reference(s) to published literature relating to what you feel is wrong or incomplete with this list.  If you feel a stage is missing from the timeline, make sure you look at the A-Z stage list, as many stages are synonymous and only one name appears on the timeline.  Thanks for the help.

Acknowledgements
This work has been supported by funds from the Gordon Getty Foundation and the Folger Foundation.  Web hosting and resources are funded by the National Science Foundation under the auspices of the CHRONOS Project.  We also wish to acknowledge that this work could not possibly exist without the dutiful efforts of hundreds of geologists from whose years of study this compilation is ultimately derived.

Authorship
Robert A. Rohde
Physics Department
University of California at Berkeley
Berkeley, CA 94720-7300
geowhen@robertrohde.com

Introduction

Geologic Timeline
(No Stages)

Geologic Timeline
(With Stages)

A-Z Stage List

Regional Information

Download Files


2003-2005 GeoWhen Database
Prepared By Robert A. Rohde


This page was last updated on Monday, January 16, 2005.