and bivalves of well nigh the recent type may be found lying side by side with chambered Orthoceratites and Terebratula." The vegetable remains of the formation are numerous but obscure, consisting mostly of carbonaceous markings, such as might be formed by comminuted sea-weed (see Plate VII.) Some of the impressions fork into branches at acute angles (see figs. 4, 5, and 6); some affect a waved outline (see figs. 7 and 8); most of them, however, are straight and undivided. They lie in some places so thickly in layers as to give the stone in which they occur a slaty character. One of my specimens shows minute markings, somewhat resembling the bird-like eyes of the Stigmaria Ficoides of the Coal Measures ;—the branches of another terminate in minute hooks, that remind one of the hooks of the young tendrils of the pea when they first begin to turn (see fig. 3). In yet another there are marks of the ligneous fibre: when examined by the glass, it resembles a bundle of horse-hairs lying stretched in parallel lines; and in this specimen alone have I found aught approaching to a proof of a terrestrial origin. The deposition seems to have taken place far from land; and this lignite, if in reality such, had probably drifted far ere it at length became weightier than the supporting fluid, and sank. It is by no means rare to find fragments of wood that have been borne out to sea by the gulf-stream from the shores of Mexico or the West Indian islands, stranded on the rocky coasts of Orkney and Shetland. * Silurian System, part i. p. 183. The dissimilarity which obtains between the fossils of the cotemporary formations of this system in England and Scotland is instructive. The group in the one consists mainly of molluscous animals,—in the other, almost entirely of ichthyolites, and what seems to have been algæ. Other localities may present us with yet different groupes of the same period,-with the productions of its coasts, its lakes, and its rivers. At present we are but beginning to know just a little of its littoral shells, and of the fish of its profounder depths. These last are surely curious subjects of inquiry. We cannot catechize our stony ichthyolites, as the necromantic lady of the Arabian Nights did the coloured fish of the lake, which had once been a city, when she touched their dead bodies with her wand, and they straightway raised their heads and replied to her queries. We would have many a question to ask them if we could,-questions never to be solved. But even the contemplation of their remains is a powerful stimulant to thought. The wonders of Geology exercise every faculty of the mind,-reason, memory, imagination; and though we cannot put our fossils to the question, it is something to be so aroused as to be made to put questions to one's self. I have referred to the consistency of style which obtained among these ancient fishes,-the unity of character which marked every scale, plate, and fin of every various family, and which distinguished it from the rest. And who can doubt that the same shades of variety existed in their habits and their instincts? We speak of the infinity of Deity,-of His inexhaustible variety of mind; but we speak of it until the idea becomes a piece of mere common-place in our mouths. It is well to be brought to feel, if not to conceive of it,-to be made to know that we ourselves are barren-minded, and that in Him "all fulness dwelleth." Succeeding creations, each with its myriads of existences, do not exhaust Him. He never repeats himself. The curtain drops at his command over one scene of existence full of wisdom and beauty, it rises again, and all is glorious, wise, and beautiful as before, and all is new. Who can sum up the amount of wisdom whose record He has written in the rocks, wisdom exhibited in the succeeding creations of earth, ere man was, but which was exhibited surely not in vain? May we not say with Milton, Think not though men were none, That heaven could want spectators, God want praise; It is well to return on the record, and to read in its unequivocal characters the lessons which it was intended to teach. Infidelity has often misinterpreted its meaning, but not the less on that account has it been inscribed for purposes alike wise and benevolent. Is it nothing to be taught with a demonstrative evidence which the metaphysician cannot supply, that races are not eternal,-that every family had its beginning, and that whole creations have come to an end? CHAPTER VI. The Lines of the Geographer rarely right Lines.-These last, however, always worth looking at when they occur.—Striking instance in the Line of the Great Caledonian Valley.— Indicative of the Direction in which the Volcanic Agencies have operated.-Sections of the Old Red Sandstone furnished by the Granitic Eminences of the Line.-Illustration.Lias of the Moray Frith.-Surmisings regarding its original Extent. These lead to an Exploratory Ramble.-Narrative.-Phenomena exhibited in the course of half an hour's Walk. The little Bay.-Its Strata and their Organisms. THE natural boundaries of the geographer are rarely described by right lines. Wherever these occur, however, the geologist may look for something remarkable. There is one very striking example furnished by the north of Scotland. The reader, in consulting a map of the kingdom, will find that the edge of a ruler laid athwart the country in a direction from south-west to north-east, touches the whole northern side of the great Caledonian Valley, with its long straight line of lakes,—and onwards, beyond the valley's termination at both ends, the whole northern side of Loch Eil and Loch Linnhe, and the whole of the abrupt and precipitous northern shores of the Moray Frith, to the extreme point of Tarbat Ness,-a right line of considerably more than a hundred miles. Nor does the geography of the globe furnish a line better defined by natural marks. There is both rampart and fosse. On the one hand we have the rectilinear lochs and lakes, with an average profundity of depth more than equal to that of the German Ocean, and, added to these, the rectilinear lines of frith; on the other hand, with but few interruptions, there is an inclined wall of rock, which rises at a steep angle in the interior to nearly two thousand feet over the level of the Great Canal, and overhangs the sea towards its northern termination, in precipices of more than a hundred yards. The direction of this rampart and fosse-this Roman wall of Scottish geological history-seems to have been that in which the volcanic agencies chiefly operated in upheaving the entire island from the abyss. The line survives as a sort of foot-track, hollowed by the frequent tread of earthquakes, to mark the course in which they journeyed. Like one of the great lines in a trigonometrical survey, it enables us, too, to describe the lesser lines, and to determine their average bearing. The volcanic agencies must have extended athwart the country from south-west to northMark in a map of the island-all the better if it be a geological one-the line in which most of our mountain ranges stretch across from the German Ocean to the Atlantic,-the line, too, in which our friths, lochs, and bays, on both the eastern and western coasts, and especially those of the latter, run into the interior. Mark, also, the line of the geological formations, where least broken by insulated groupes east. |