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 mining in the United Kingdom or low-carbon sources and loss of industry due to globalisation. Oil and gas reserves are predicted to run out long before coal, so gas could be produced from coal by gasification. On 21 April 2017, Britain went a full day without using coal power to generate electricity for the first time since the Industrial Revolution, according to the National Grid. In April 2018, a new record was set of 55 hours without coal, which in turn was broken by a period of more than 72 hours without coal a few days later. Coal mining in the United Kingdom Coal mining