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The First Coal Plants
Nature Bulletin No. 329-A   January 25, 1969
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation

Coal has been called "the mainspring" of our civilization. You are probably familiar, in a general way, with the story of how it originated ages ago from beds of peat which were very slowly changed to coal; and how it became lignite or brown coal, sub-bituminous, bituminous, or anthracite coal, depending on bacterial and chemical changes in the peat, how much it was compressed under terrific pressure, and the amount of heat involved in the process. You also know that peat is formed by decaying vegetation in shallow clear fresh-water swamps or bogs, but it is difficult to find a simple description of the kinds of plants that, living and dying during different periods of the earth's history, created beds of peat which eventually became coal.

Geologists and other scientists have worked out a timetable of the changes that have taken place during the last billion and a half years which they have divided into "Eras", the eras into "Periods", and the periods into "Epochs". Each of these has been named, and the kinds of plants and animals which existed, if any, have been named. So, although we do not like to use eight-cylinder words in our bulletins, we are forced to do it in this case.

The estimates vary as to how long ago each period began and ended but that is not important. To those scientists, a million years is only a "drop in the bucket", although the last million includes the Ice Age and the first evidence of manlike creatures. The span of recorded human history, a mere 5000 years, is only a pinpoint in the whole picture. That picture has been built up from a study of minerals, rocks and fossils, coal being one kind of rock -- a sedimentary rock. Lumps of coal, examined under a microscope, are found to contain spores, seeds, stems, bits of leaves, or other plant parts . Fossilized wood, including parts of tree trunks, have been found in coal beds. In the roof of a coal mine near Trinidad, Colorado, there is the impression of a mat of huge palm leaves. It is not rare to find masses of leaves, each having hundreds of leaflets, of the tree ferns which once existed. Beneath some coal beds, in the clay which was the bottom of an ancient swamp, are found the stumps and roots of primitive trees.

It appears that some plants became amphibious -- able to live in the water or out of it, as the level changed -- and that about 390 million years ago, in the Silurian Period, some of these became capable of living entirely on land. Our oldest coal comes from peat formations started then. Those first land plants were small, drab, leafless and almost rootless, resembling a combination of an algae with a rush or a sedge. Although they were all descendants from the algae, they had what has been characterized as "the heroic pioneering spirit that brought them out of the sea", and their offspring seem to have developed almost simultaneously into a bewildering array of types. Some specialized along the lines of ferns, others as club mosses, and still others as horsetails (primitive jointed plants that still live and which we call "scouring rushes").

Within the next 60 million years, extending into the Devonian Period, nearly all of our major divisions of the plant kingdom developed and the Age of Ferns began. The early ferns were peculiar. Some were woody; some had large breathing pores on their stems. Presently the tree ferns appeared and dominated the landscape for the next 175 million years -- longer than any other type of plant, then or since.

Tip your hat to the next fern you see, and say "Hello, Old Timer ! "

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