In considering the existence of inland peat-bogs, we must not lose sight of the fact that there are subterranean forest-beds on various parts of our coasts, which also rest upon their own beds of peaty matter, and very possibly, when in the future they are covered up by marine deposits, they will have fairly started on their way towards becoming coal.

Peat-bogs do not wholly consist of peat, and nothing else.  The trunks of such trees as the oak, yew, and fir, are often found mingled with the remains of mosses and reeds, and these often assume a decidedly coaly aspect.  From the famous Bog of Allen in Ireland, pieces of oak, generally known as “bog-oak,” which have been buried for generations in peat, have been excavated.  These are as black as any coal can well be, and are sufficiently hard to allow of their being used in the manufacture of brooches and other ornamental objects.  Another use to which peat of some kinds has been put is in the manufacture of yarn, the result being a material which is said to resemble brown worsted.  On digging a ditch to drain a part of a bog in Maine, U.S., in which peat to a depth of twenty feet had accumulated, a substance similar to cannel coal itself was found.  As we shall see presently, cannel coal is one of the earliest stages of true coal, and the discovery proved that under certain conditions as to heat and pressure, which in this case happened to be present, the materials which form peat may also be metamorphosed into true coal.

Darwin, in his well-known “Voyage in the Beagle” gives a peculiarly interesting description of the condition of the peat-beds in the Chonos Archipelago, off the Chilian coast, and of their mode of formation.  “In these islands,” he says, “cryptogamic plants find a most congenial climate, and within the forest the number of species and great abundance of mosses, lichens, and small ferns, is quite extraordinary.  In Tierra del Fuego every level piece of land is invariably covered by a thick bed of peat.  In the Chonos Archipelago where the nature of the climate more closely approaches that of Tierra del Fuego, every patch of level ground is covered by two species of plants (Astelia pumila and Donatia megellanica), which by their joint decay compose a thick bed of elastic peat.

“In Tierra del Fuego, above the region of wood-land, the former of these eminently sociable plants is the chief agent in the production of peat.  Fresh leaves are always succeeding one to the other round the central tap-root; the lower ones soon decay, and in tracing a root downwards in the peat, the leaves, yet holding their places, can be observed passing through every stage of decomposition, till the whole becomes blended in one confused mass.  The Astelia is assisted by a few other plants,—­here and there a small creeping Myrtus (M. nummularia), with a woody stem like our cranberry and with a sweet berry,—­an Empetrum (E. rubrum),