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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.