<AREA SHAPE=RECT COORDS="5,304,19,319" HREF="!Deposits of loose mineral material, called sediments, completely covered the peat bed. As these sediments continued to pile up over the bed, they compressed the peat.">
The formation of coal involved three main steps. (1) The remains of dead plants turned into a substance called <I>peat.</I> (2) The peat became buried. (3) The buried peat was subjected to great pressure. After thousands or millions of years under pressure, the peat turned into coal. Each of these steps is illustrated here.<NP>
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World Book diagram by Jean Helmer</P>
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