In 1822, William Phillips and W.D. Conybeare published a paper in which a unit of limestone strata between the old and new red sandstones. They called it the Carboniferous, from the Latin ferre; meaning "to bear", and carbo ; meaning "coal" (referring to the vast stretches of coal-bearing strata).

      
 
 
In the United States the Carboniferous was broken down into the Mississippian and the Pennsylvanian.