of any of the three geologic epochs (lower, middle and upper) within the Carboniferous period from 318 to 299 million years ago; marked by a high oxygen atmosphere and the rise of reptiles and winged insects
In North America, the interval of geologic time roughly equivalent to what is internationally designated the Late Carboniferous Period (323-290 million years ago). Because the rocks that originated during this span of time are widespread in the state of Pennsylvania, some U.S. geologists favour the term over Late Carboniferous Period, which was first adopted in Europe