Coal the heat and pressure of deep burial causes the loss of water, methane and carbon dioxide and an increase in the proportion of carbon. Thus first lignite (also called "brown coal"), then sub-bituminous coal, bituminous coal, and lastly anthracite (also called "hard coal" or "black coal") may be formed. The wide, shallow seas of the Carboniferous Period provided ideal conditions for coal formation, although coal is known from most geological periods. The exception is the coal gap in the Permian–Triassic extinction event, where coal is rare. Coal is known from Precambrian strata, which predate land plants—this coal is presumed to
Coal breaker rolled down a chute and then through an inclined cylindrical screen. The screen had a mesh which was fine toward the front and became progressively less so toward the end. Larger chunks of coal, falling inside the cylinder as it rotated, broke up and eventually passed through the screen. Impurities, which were heavier, tended to exit the breaker at the end of the screen. The sorted coal would then be collected in bins below the screen, and transported to market. A fellow Pennsylvanian, Gideon Bast, licensed the technology from Battin, and erected the first commercial coal breaker in Schuylkill County,