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
Robert A. Burns Burns leaving a farewell note on his website with a photo of him stretched out in front of a tombstone with his name on it. Robert A. Burns Robert A. Burns (May 27, 1944 - May 31, 2004) was an American art director and production designer who worked on many films including "The Texas Chain saw Massacre", "The Hills Have Eyes", "The Howling", "Re-Animator", and "From Beyond". Burns attended the University of Texas where he was editor of "The Texas Ranger". Burns first entered the film industry as the casting director and art director of Tobe Hooper's 1974 horror film