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
A Scientific Support for Darwinism case, as well as announce the results in a press release. The petition was not completed sufficiently early to submit it as part of an "amicus curae" brief for the Dover case. However, if the case was to go to the US Supreme Court, the petition could have been submitted as an "amicus" brief at that time. R. Joe Brandon emphasized that this "Four Day Petition" did not mean that scientific issues are settled by majority vote. What Brandon maintains is that this is an indication of the level of scientific consensus that accepts evolution as a viable established scientific