The
Pennsylvanian (also known as
Upper Carboniferous or
Late Carboniferous) is, in the
ICS geologic timescale, the younger of two
subperiods (or upper of two
subsystems) of the
Carboniferous Period. It lasted from roughly Ma (million years ago). As with most other
geochronologic units, the
rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain by a few million years. The Pennsylvanian is named after the U.S. state of
Pennsylvania, where the coal-productive beds of this age are widespread.