The common idea on how to make coal is to accumulate an incredible thickness (many hundreds of feet) of peat which will then compressed into coal. Nothing could be farther from the truth!

As plant material dies and falls to the bottom of the swamp it is partially decayed producing peat. Once the peat layer reaches around 30 feet thick, the bottom portion has changed into a black, cheesy, gel-like material gytta. As more peat accumulates, the lowermost layers convert to gel. The peat/gel process is all due to bacterial decay. It is this gel that turns into coal, so for a 50 foot of coal bed we need only fifty feet of gel. At no time is there a need for hundreds of feet of peat to accumulate.

This gel-like material is not squeezed into coal, it must be heated above 1200 F (usually above 2120 F) which then bakes it into the various coals. Coal is the result of bacterial decay followed by heat.