ance in such a position, is obviously the opposing of mobility to mobility: the keeping up a fleet sufficient anywhere to meet and give account of the enemy, able to bring our guns up to the muzzle of his, and at last to end the strife by the rush with the invincible boarding-pike. Having thus considered, in such details as our limits permitted, and supplying the references by which they may be tested and pursued, the total force which this country possesses for the maintenance of its security, it is scarcely necessary that we should anticipate the conclusions to which our readers will probably come. Taking for our guide the opinions of the greatest of modern generals upon the attack and defence of this island, and supplementing them with an investigation of the extent to which subsequent discoveries have modified the data on which they rested, we have shown that our present position is stronger than it ever was. We have shown that our power by sea and land is numerically as great as when we waged a deadly war with the master of Europe; that it largely exceeds what our own great commander deemed necessary for defence; that the progress of science has rendered secure whatever on our side might formerly have been deemed doubtful, and given into our hands, above those of any other nation, the means by which a numerical superiority is many times multiplied in operative effect. Such considerations will, we trust, not be unserviceable either in correcting and bringing to the test of a definite standard the loose statements of political leaders, or in reminding us that it is our pleasure, through design or ignorance, to keep on foot a military power which is suitable, not for time of peace, but for time of war. The defence of this country is too sacred a thing to be left as a material for the manufacture of political capital; and on the other hand, the misery diffused by the maintenance of taxation on a scale necessary to support overgrown establishments, is too deep and widespread, to permit us supinely to continue it through mere lazy acquiescence. Let us at least know our own minds. If we mean only to stand on our defence, let us consider the proper means and the proper strength requisite for attaining that object; but if we think fit to hold a greater power in readiness, let us remember that it is needful only for offensive war, and only to be justified by the distinct acknowledgment that such a war is impending. THE NORTH BRITISH REVIEW. NOVEMBER 1863. ART. I.-1. On the Revolutions of the Earth's Surface. Sir JAMES HALL. Transactions of the Royal Society of Edinburgh, vol. vii. 1812. 2. Researches in Newer Pliocene Geology, 1836-1862. SMITH, Esq. of Jordanhill. Glasgow, 1862. JAMES 3. On the Evidences of the former Existence of Glaciers in Scotland, Ireland, and England. L. AGASSIZ. Proceedings of the Geological Society, vol. iii., and Edinburgh New Phil. Journal, vol. xxxiii. p. 217. 1840. 4. Notes on the Traces of Ancient Glaciers among the Cuchullin Hills in Skye. PRINCIPAL FORBES. Edinburgh New Phil. Journal, vol. xl. p. 76. 1845. 5. On the Connexion between the Distribution of the Existing Fauna and Flora of the British Isles, and the Geological Changes which have affected their Area, especially during the Epoch of the Northern Drift. EDWARD FORBES. Memoirs of Geol. Survey, vol. i. 1846. 6. On Grooved and Striated Rocks in the Middle Region of Scotland. CHARLES MACLAREN. Edin. New Phil. Journal, vol. xlvii. p. 161. 1849. 7. On Glacial Phenomena in Scotland and parts of England. ROBERT CHAMBERS. Edin. New Phil. Journal, vol. liv. p. 229. 1852. 8. On the Ice-worn Rocks of Scotland. T. F. JAMIESON. Quart. Jour. Geol. Society, vol. xviii. 1862. 9. On the Glacial Origin of Lakes. A. C. RAMSAY. Quart. Jour. Geol. Society, vol. xviii. 10. On the Drift of the British Islands" Antiquity of Man." Sir CHARLES LYELL. 1863. VOL. XXXIX.--NO. LXXVIII. T 11. On the Phenomena of the Glacial Drift of Scotland. ARCHIBALD GEIKIE. Trans. of Geol. Soc. of Glasg., vol. i. part ii. 1863. 12. On the Parallel Roads of Glen Roy. T. F. JAMIESON. Quart. Jour. Geol. Society, vol. xix. 1863. MANY a long century has passed away since our forefathers began to speculate on the origin of those immense masses of clay, gravel, and sand, which are spread as a more or less continuous covering over well-nigh the whole of the surface of Scotland. The Lowlands are buried deep beneath this mantle of detritus, save here and there where a knob of black rock, or a group of hills rises above it, while up the glens and valleys of the Highlands, parts of the same wide series of deposits may almost everywhere be traced. Nor does it require any geological training to be able to detect these features. They are of a kind that cannot escape observation. Thus the gravel and sand are often arranged in singular ridges like huge lines of rampart, or in conical grassy hillocks, whose greenness forms in many places a strange contrast to the brown barrenness of the surrounding moors. Now and then, too, among the fertile fields of the low country, the eye rests on huge boulders, which must have come from the far-off mountains of the Highlands. And blocks of the same kind may be found high on the sides, and even on the summits of the Lowland hills. So obvious and obtrusive are these phenomena, that they could not but force themselves on the attention, even in the rude ages, long before science had arisen to take any interest in them. Hence sprang up those legendary stories of wizards and warlocks, brownies and goblins, to whose supernatural agency the Scottish mind early attributed the otherwise inexplicable gravel-mounds and boulders. It was a quaint and beautiful superstition that peopled these verdurous hillocks or tomans with shadowy forms, like diminutive mortals, clad in green silk or in russet grey, whose unearthly music came sounding out faintly and softly from underneath the sod. The mounds rose so conspicuously from the ground, and whether in summer heat or winter frost, wore ever an aspect so smooth and green, where all around was rough with dark moss-hags and moor, that they seemed to have been raised by no natural power, but to be in very truth the work of fairy hands, designed at once to mark and to guard the entrance to the fairy world below. The hapless wight who, lured by their soft verdure, stretched himself to sleep on their slopes, sank gently into their depths, and after a seven years' servitude in fairy-land, awoke again on the selfsame spot. Like young Tamlane "The Queen of Faëries keppit him In yon green hill to dwell." Popular Explanations of the Drift. 287 The same fancy which found a supernatural origin for the mounds of sand and gravel had similar explanations to give of the strange elongated ridges of like materials known in Scotland as kames. According to one tradition, these ridges are the different strands of a rope which a troublesome elfin was commanded by Michael Scott to weave out of sand. The strands were all prepared, but when the imp tried to entwine them, each gave way, and hence the broken parts of the kames have remained to this day. Michael seems to have had no small amount of work in altering the surface of the country. Thus there is a deep gash through a sandy ridge at the south end of the Pentland Hills, and not far off stands a green conical sandhill. The wizard is said to have dug the trench and piled up the hill in the course of a single night. About ten miles farther west he attempted to dam up the river Clyde, by getting a number of witches to carry large boulders from a neighbouring eminence. The spell was broken, however, in the midst of the performance, and the long line of boulders in the different stages of transport may still be partially traced on the ground. In short, throughout many districts of the country, the peculiarly obtrusive nature of the superficial geology, and the difficulty of connecting it with any of the operations of nature now visible, have given rise to many of the supernatural legends which still linger in tradition. It was but natural that when geology as a science began to attract attention in these islands, the vast accumulations of clay, sand, gravel, and boulders scattered over the surface, should claim the notice of the early observers. These deposits formed the monuments of the last of the long succession of geological revolutions which the country had undergone. They were regarded as proofs of a violent cataclysm, whereby the hardest rocks were ground down and furrowed so as to cover the whole country with its own ruins, in the form of heaps of detritus. Nor was it difficult to see in such phenomena proofs of that great deluge which was believed to have covered the surface of the entire globe at the time of Noah. The hypothesis of violent oceanic debacles was ingeniously worked out by Sir James Hall, and influenced all the speculations of geologists on this subject for fully quarter of a century. By degrees, however, it was seen that the phenomena were of too definite and complicated a kind, and presented traces of too many different agencies to have been the result of any sudden and transient catastrophe. Then came the hypothesis of ocean currents and icebergs, which has in turn to be abandoned, as at the best but a partial explanation of the facts which it was proposed to elucidate. As investigations have advanced, the subject has always seemed to deepen in obscurity as well as interest. There is hardly a geologist of standing who has not been seduced into this domain, no matter how widely it might be separated from his more usual field of labour. Hence no part of the geology of the country has been so fruitful a source of scientific memoirs, papers, and notices of every variety of size and treatment. After groping in the dark for at least fifty years, geologists seem at last to be coming to an agreement as to the true origin and history of some of the superficial formations. We propose, therefore, in the following pages, to present the reader with an outline of the facts which have been observed, and a view of the general tendency of scientific reasoning regarding them. The surface of Scotland, like that of Ireland and large tracts of England, as well as the whole of Scandinavia and Northern Europe, has a peculiar contour, which, since it is almost everywhere more or less visible, irrespective of the nature of the rock on which it shows itself, must evidently be the result of one great process acting long after all the hard rocks were formed. This contour consists in a rounding and smoothing of the hills and valleys into long flowing outlines. What were once prominent crags have been ground down into undulating or pillow-shaped knolls, and deep hollows or gentler depressions have been worn in the rocks, not at random, but in a recognisable system. Thus the Lothians and Fife have had their surface scooped out into long parallel hollows and valleys, which maintain a wonderful persistence in an easterly and westerly direction. In Galloway, we see the minor depressions diverging southwards, from the mass of high ground that lies between St. Patrick's Channel and Nithsdale. Down the western coasts, from Cape Wrath to the Mull of Cantyre, and among the deep sea-lochs of the Firth of Clyde, the same evidence occurs of some agency which has pressed outwards and seawards, grinding down the surface of the hardest rocks, and giving a rounded outline to the whole country. It is true, indeed, that this contour has often disappeared. The rains and frosts of ages have at last, in not a few places, succeeded in restoring to the rocks their ancient rugged character. Yet, even in the wildest Highland scenery, where the casual tourist may see, perhaps, nothing but thunder-riven crags and precipices, and glens blocked up with their ruins, the geologist can yet often detect traces of the same universal smoothing and moulding. Nay, it is precisely amid such scenes that he is most vividly impressed with the fact that the surface of the country has everywhere been ground down by a vast general agent, for he there sees what are the natural outlines which the rocks assume when left to the ordinary tear and wear of the elements. Instead of smooth undulating outlines, he notes craggy pre |