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12 Coal
Early Stages: Peat and Lignite
The transformation of vast prehistoric piles of soggy, semi-rotting plants into coal
was not a simple one-stage process. It was slow and continuous, with greatly varied
conditions of temperature, types of plants, amount of moisture, and more, including
how deep the remains were buried. This makes coal different in every place it is now
found. But overall, there were several stages in coal formation, or coalification: peat,
lignite, sub-
bituminous
coal, bituminous coal, and anthracite. Types of coal matter
because each type contains a different level of carbon. The higher the carbon content,
the more heat energy produced when the coal is burned.
Piles of peat dug up in Ireland.