Carboniferous

Series of sandstones, limestones and shales, among which occur numerous beds of coal, whence the name. Though coal is found on several other geological horizons, it is inferior to the true carboniferous coal. The scheme below may give an idea of the general order of the beds in N. America and their approximate equivalents in Europe. On both continents the true coal measures reach a thickne of more than 12,000 ft. In both they are underlaid by a conglomerate, and lower down by a ma ive limestone. The genera and sometimes the species of coal-forming plants are identical in both; the coal occurs in strata ranging from many feet in thickne down to mere films. The coal-fields of Australia are remarkable for plants of Mesozoic type, indicating that continent as their aboriginal home. Few rocks exceed the Carboniferous or Mountain Limestone in the richne of their organic remains. IMG:content-0736.png:[blocks in formation] Limestone. A similar limestone occurs in N. America on the same horizon, and has been called sub-carboniferous.