440.7 - 440.1 Ma

The definition of this interval in the timescale Silurian of North America is taken from the following source:

• F. M. Gradstein, J. G. Ogg, and A. G. Smith. 2004. A Geologic Time Scale 2004 1-589 view

The top and bottom ages 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.

There are intervals in 4 timescales which overlap this one. show

• International Chronostratigraphic Timescale: Aeronian age, Llandovery epoch
• Silurian of the Baltic: Raikkula age
• Silurian of England: Cowleigh Park age
• Silurian of North America: Medinan age, Alexandrian age

This interval is used in the definition of 20 collections

A total of 20 collections with 163 occurrences lie within this time span