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

There are 13 timescales which overlap this one. show

• Obsolete Names for ICS Units
• Ten Million Year Bins
• Permian of the Russian Platform
• Permian of the Pamirs
• Permo-Triassic Subages of Eastern Europe
• Permian Subages of Germany
• 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.

This timescale is used in the definition of 167 collections