[145] It is unfortunate that few writers on this subject have combined with the knowledge of the geological features of the coal a sufficient acquaintance with the phenomena of modern marshes and swamps, and with the conditions necessary for the growth of plants such as those of the coal. It would be easy to show, were this a proper place to do so, that the "swells," "rock faults," splitting of beds, and other appearances of coal seams quite accord with the theory of swamp accumulation; that the plants associated with _Sigillariæ_ could not have lived with their roots immersed in salt water; that the chemical character of the underclays implies drainage and other conditions impossible under the sea; that the composition and minute structure of the coal are incompatible with the supposition that it is a deposit from water, and especially from salt water; and that it would be more natural to invoke wind driftage as a mode of accumulation for some of the sandstones, than water driftage for the formation of the coal. At the same time it is pretty certain that such beds as the cannels and earthy bitumens which appear to consist of finely comminuted vegetable matter, without mineral charcoal, may have been deposits of muck in shallow lakes or lagoons. [146] _Journal of Geol. Socy._, vols. x. and xv., and "Acadian Geology." It is also noticeable that, in conditions such as those of the coal formation, it would be likely that some plants would be specially adapted to occupy newly emerged flats and places liable to inundation and silting up. I believe that many of the Sigillariæ, and still more eminently the _Calamites_, were suitable to such stations. There is direct evidence that the nuts named Trigonocarpa were drifted extensively by water over submerged flats of mud. Many _Cardiocarpa_ were winged seeds which may have drifted in the air. The Calamites may, like modern _Equiseta_, have produced spores with elaters capable of floating them in the wind. One of the thinner coals at the Joggins is filled with spores or spore cases that seem to have carried hairs on their surfaces, and may have been suited to such a mode of dissemination. I have elsewhere proved[147] that at least some species of _Calamites_ were, by their mode of growth, admirably fitted for growing amid accumulating sediment, and for promoting its accumulation. [147] "Acadian Geology," chapter on Coal Plants.