The term "Carboniferous" had first been used as an adjective by Irish geologist Richard Kirwan in 1799, and later used in a heading entitled "Coal-measures or Carboniferous Strata" by John Farey Sr. in 1811, becoming an

Average global temperatures in the Early Carboniferous Period were high: approximately 20 °C (68 °F). However, cooling during the Middle Carboniferous reduced average global temperatures to about 12 °C (54 °F). Atmospheric carbon dioxide levels

Romer's gap
The first 15 million years of the Carboniferous had very limited terrestrial fossils. This gap in the

The Carboniferous is divided into two subsystems, the lower Mississippian and upper Pennsylvanian, which are sometimes treated as separate geological periods in North American

A global drop in sea level at the end of the Devonian reversed early in the Carboniferous; this created the widespread

Carboniferous rocks in Europe and eastern North America largely consist of a repeated sequence of limestone, sandstone, shale and coal beds. In North America, the early Carboniferous is

Plants
Early Carboniferous land plants, some of which were preserved in coal balls, were very similar to those of the preceding Late Devonian,