The interval definitions in this timescale are derived from the following sources:

• F. M. Gradstein, J. G. Ogg, M. D. Schmitz and G. M. Ogg. 2020. Geologic Time Scale 2020 view
• W. B. Harland, R. L. Armstrong, A. V. Cox, L. E. Craig, A. G. Smith and D. G. Smith. 1990. A Geologic Time Scale 1989. view
• K. M. Cohen, S.C. Finney, P.L. Gibbard and J.-X. Fan. 2023. The ICS International Chronostratigraphic Chart v2023/09. view
• F. M. Gradstein, J. G. Ogg, and A. G. Smith. 2004. A Geologic Time Scale 2004 1-589 view

There are 13 timescales which overlap this one. show

• Obsolete Names for ICS Units
• Ten Million Year Bins
• Permian of the Pamirs
• Permo-Triassic Subages of Eastern Europe
• Permian Subages of Germany
• Permian of Western Europe
• Permian of the Salt Range
• Permian of China
• Permian of North America
• Carbo-Permian of the Russian Platform
• Carboniferous of Western Europe
• Carboniferous of North America
• Permian-Jurassic of New Zealand

Interval boundaries marked with * have been interpolated based on the differences between the ages for international timescale boundaries quoted in the source and the currently accepted ages for those boundaries.

Interval names marked with † are no longer in current use.

This timescale is used in the definition of 181 collections