What is "serpukhovian"

The Serpukhovian is in the ICS geologic timescale the uppermost stage or youngest age of the Mississippian, the lower subsystem of the Carboniferous. The Serpukhovian age lasted from Ma to Ma. It is preceded by the Visean and is followed by the Bashkirian.

The Serpukhovian correlates with the lower part of the Namurian stage of European stratigraphy and the middle and upper parts of the Chesterian stage of North American stratigraphy.