Figure 9—Reconstruction of coal-forming swamp.
HOW DO WE KNOW THAT COAL WAS DERIVED FROM PLANT MATERIALS?
Although plant impressions or fossilized wood can be seen in coal, they are more common in shales and sandstones associated with the coal. Often roots can be seen in the clay that lies just under the coal, and in some places stumps of trees from the coal swamp forest are preserved in the sediments adjacent to the coal ([fig. 10]). When pieces of coal are examined with a microscope, carbonized plant remains can be seen.
HOW MANY COAL SEAMS ARE PRESENT IN ILLINOIS?
There are at least 40 different coal seams in Illinois, but most are relatively thin. Seven coal seams have been mined extensively, and all together 20 or more have been mined.
Figure 10—Some root, stem, and leaf fossils found in Illinois coal-bearing rocks.
Neuropteris ⅖× Nosopteris stem ⅔× Neuropteris ½× Lepidodendron ⅖× Pecopteris ⅔× Stigmaria ⅖× Annularia ⅔× Spiropteris ⅔× Sphenophyllum 1×