It took about 160 years to lay down what is now a 1 ft thick layer of lignite coal; 260 years for a foot of bituminous, and about 490 years for a foot of anthracite. An eight-foot coal seam requires about 2,100 years.
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It took about 160 years to lay down what is now a 1 ft thick layer of lignite coal; 260 years for a foot of bituminous, and about 490 years for a foot of anthracite. An eight-foot coal seam requires about 2,100 years.