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Why are low-oxygen conditions important for peat and coal formation?

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coal utilization Cross-regenerative coke oven. (A) Cross section, showing the alternating arrangement of flue walls and ovens; (B) longitudinal section, showing (left) a series of combustion flues in a single flue wall and (right) part of a long, slotlike oven.

Low-oxygen, or anaerobic, conditions are essential for the formation of peat and, subsequently, coal because they prevent the complete decomposition of organic matter.12

In environments where oxygen is readily available, aerobic microorganisms and fungi actively break down plant material, converting it primarily into gaseous and liquid products. By contrast, in waterlogged, oxygen-deprived settings, this microbial activity is significantly restricted or eliminated. This lack of oxygen allows the plant remains to accumulate and undergo partial decomposition, transforming into peat rather than fully decaying.12

As this peat is buried under increasing layers of sediment, it is eventually subjected to the geochemical processes of coalification, where heat and pressure over time convert the organic material into various ranks of coal, such as lignite, bituminous coal, and anthracite. Without the initial preservation provided by anaerobic conditions, the organic precursors necessary for coal formation would be lost to complete decay.1342