A Lecture on "Coal."
We finished last month with the fact that plant-remains were found in plenty both above and below the coal. I shall draw your attention first to the roof-shale—or clay over the coal—"over-clay" as it is often called: for in this the great majority of remains are preserved. In the roof-shale two kinds of plants are the most conspicuous—fern-leaves, and the diapered cylinders mentioned in our last. These are the prevailing fossils, though there are a great many besides. Looking first at the
... first at the fern-leaves, which from their beautiful forms cannot fail to strike the observer's eye, one is surprised to notice the extremely perfect state in which they occur. Delicate fronds, spread out as for the sheets of an herbarium, with hardly a leaflet disturbed from its true place, crowd the roof-shales of nearly all coal-mines. Dr. Buckland sang the praises of this beautiful tracery, which covers the roof of the mine, in glowing strains such as it will not do for a plain geologist to imitate. I have a lurking suspicion, however, that the great doctor conceived the passage not in the mine, but out of it. At least one hundred and twenty species are known in our British coal-strata. So perfect are they occasionally, that the little fruit-patches (sori, as botanists term them), are found upon the backs of the fronds. This is not very common, except in one kind—the Pecopteris, which happens to be more abundant than most of the others, and in some species of this the fruit is found.