my predecessors in this Chair to attach Mr. Maclaren to his views, I must be permitted to direct your attention to the practical results at which this gentleman has arrived in some prominent cases. Observing blocks of greenstone on Arthur's Seat, which, from their peculiar structure, must have been transported from Salisbury Crags, a lower hill, and separated from the former by an abrupt valley, Mr. Maclaren infers, that if the present surface of the land be argued upon (and in all questions of glaciers this is a postulate), neither glacier, nor iceberg, nor current will ex. plain the fact. It is unnecessary that I should here examine this author's hypothesis, by which, in order to solve the local problem, he restores the inclined stratified masses of Salisbury Crags to such an extent as to give them an altitude in ancient times superior to that of Arthur's Seat; for whether we adopt his ingenious view, involving a mighty subsequent denudation, or suppose that in the oscillations of this plutonic tract the former low and high points of land have been relatively depressed and elevated, it is obvious, from the very structure of the rocks, that in both cases a subaqueous, and not a subaerial condition is called for to explain the appearances, and this too, be it recollected, on the summits of the highest hills in the immediate vicinity of the Scottish metropolis, in and around which the action of glaciers has been supposed to be visible at such lower levels! Among the examples of the scratched and polished surfaces of rocks near Edinburgh, I do not perceive that the glacialists have grappled with certain appearances on which Dr. Buckland formerly dwelt with so much pleasure, viz., the grooved or channeled surfaces of the Braid Hills, first pointed out by Sir James Hall, and which the great chemical geologists attributed to a powerful rush of waters. When I visited the low ridge in question with Dr. Buckland and other friends,* my conviction was that these grooves, though then attributed by Dr. Buckland to glacial action, are due neither to that agency, nor to any rush of waters, but are simply the result of the changes which the mass of the rock underwent, when it passed from its former molten or pasty condition into a solid state. These appearances differ essentially from ordinary glacial scratches or scorings. They are, in fact, broad undulations or furrows, and instead • Dr. Graham and Mr. Maclaren were of the party, in October, 1840. + Plaster casts of these exist in the Geological So ciety. of trending from the higher grounds to the Firth or Forth, as would naturally be the case if they were due to the expansion and descent of glaciers, they rise up to the very summit of the low ridge in a direction transverse to its bearing, and with no neighboring point of ground higher than that on which they occur. On clearing away the thin turf which barely covered the rock, some of these undulations in the surface appeared wide enough to contain the body of a man, and though observing a rude sort of parallelism, their forms were often devious. As their surface was smooth, not much unlike the usual aspect of the so-called "moutonnés" rocks, the glacialists of our party at first seemed to be proving their case, when suddenly a discovery destroyed, at least in my opinion, their theory; for in the adjacent quarries of the same hill, at a much lower level, and upon beds just uncovered by the workmen from beneath much solid stone, other sets of undulations or grooves were detected, so like to those upon the summit of the hill, that a little atmospheric influence alone was required to complete their identity. My belief therefore is that the undulations were caused by the action which took place when the stone was solidified. Phenomena of a similar nature to the Scottish have been since observed in Wales by our late Fellow, Mr. Bowman. Captivated by the glacial theory, and having himself endeavored to show that it could even be as successfully applied to the south as to the north of Scotland, he examined the highest region of Wales, with the geological structure of which he was previously familiar, half convinced, a priori, that he would naturally find in those mountainous tracts some proof in support of the new views which he had adopted. He, however, quitted that country without having been able to observe any evidence whatever in favor of the Alpine theory, though his journey enabled him to detect several examples of striated rocks, which in unskilful hands might have been mistaken for the effects of glacial action; and these he holds up as warning beacons. After stating that there are, in his opinion, no terraces which any follower of Agassiz can construe into "moraines," whether terminal, medial, or lateral, on the flanks of the mountains of Snowdon, the Arenigs, or the Berwyns, he describes three distinct and differently formed sets of parallel markings which he observed in the newly uncovered surfaces of the schistose Silurian rocks, and shows satisfactorily how such appearances, as well as the tops of the joints, might be mistaken by cursory observers for scratches, although they are in fact due to structure. with all the data upon which our science has been reared, to suppose that when such shells were deposited, the parts of the mountain so affected were permanently beneath the sea, than to call into play the assumption of the passage of so mighty a wave? At one moment the argument used is, that scratchings and polishings of rock must have been done by ice, because in existing nature it has been found that ice can produce such effects; and in the same breath we are told that beds of shells have been placed on a mountain by an agency which is truly supernatural. from that vera causa, and try to force the many and highly diversified superficial phenomena of the surface of the globe, into direct agreement with evidences of the action of ice under the atmosphere, and you will be driven forward like the ingenious author of the theory, so to apply it to vast tracts of the globe, as in the end to conduct Unlike Mr. Bowman, Dr. Buckland has not confined his views of the action of glaciers to Scotland, but applies them largely to the north of England and to Wales. He has recently endeavored to satisfy us, that the rocks on the sides of the chief valleys in the latter country which open out from a common centre of elevation are striated, worn, and polished in the direction of the present water-courses, and these he conceives to be evidences of former glaciers, which filled up all the valleys radiating from Snowdon to a distance of many miles from In fact the "glacier" theory, as extended a common centre. I confess I see almost by its author, in proving too much, may be insurmountable objections to this view. said to destroy itself. Let it be limited to Apart from other evidence, the very physi- such effects as are fairly deducible from cal geography of this tract is at variance the Alpine phenomena so clearly described with the construction of such an hypothesis. by Agassiz, and we must all admire in it a In the Alps, and indeed in every other part vera causa of exceeding interest; but once of the world in which they have been observ-pass the bounds of legitimate induction ed, the length of glaciers is in ratio to the height of the mountains from which they advance, or, to use the words of Agassiz, from which they expand. Now, whilst in the present days, a small glacier hangs to the sides of a mighty giant like Mont Blanc, having the altitude of 15,000 feet, our Welshhills, having a height only of 4000 feet, had glaciers, by the showing of Dr. Buck-you to the belief, that not only both northern land, of a length of many miles. Again, in the same memoir, which fill so large a portion of the principality with glaciers, the author comments upon certain facts already well known to us, viz., the existence upon Moel Tryfane and the adjacent Welsh mountains of sea-shells of existing species, at heights of 1500 and 1700 feet above the sea, where they are associated with mixed detri-ceed to fill the Baltic and Northern Seas, tus of rocks transported from afar, all of which have travelled from the north, the hard chalk and flints of the north of Ireland being included. How are we to reconcile these facts with the theory that the greater part of the country in question was frozen up under the atmosphere in some parts of the same modern period? Unable otherwise to explain how marine shells should be found on mountains which are supposed to have been previously and during the same great period occupied by terrestrial glaciers, the accumulation of ages, Dr. Buckland invokes anew the aid of the old hypothesis of a great wave. This wave, rolling from the north, must have dashed over the mountains to a height of near 2000 feet, depositing, as it went, gravel, boulders and fragments, derived from places 200 miles distant, and transporting also marine shells in its passage. But is it not more natural and accordant and southern hemispheres, but even quasi tropical regions, were shut up during a long period in an icy mantle. Once grant to Agassiz that his deepest valleys of Switzerland, such as the enormous chasm of the lake of Geneva, were formerly filled with solid snow and ice, and I see no stoppingplace. From that hypothesis you may pro But cover Southern England, and half of Ger- But though the Alpine glacial theory be new, the scratches and polished surfaces of rocks are by no means of recent observation. Many Swedish miners, from the days of Tilas and Bergman, failed not to remark how their mountain sides were furrowed, and in our own times, Sefström* of Sweden, and Böhtlingk of Russia, have not only narrowly traced them over wide regions, but have endeavored to account for them. The first of these authors remarked, that nearly all the hard rocks of this country had a 66 worn or weather side," and a highly escarped or "lee side," the former being exposed to the north and the latter to the south; and having further shown that the detritus had generally been carried from N. to S., he called the worn face the "weather side," and the higher and jagged extremity of such ridges the "lee side." Extending his observations to many hundred places, he divided these scratches into what he calls normal and side furrows, showing that in the latter there are frequent aberrations from the persistent courses of the former. Although he had been at first disposed to think, from the data in a given country around Falun, that the normal lines were invariably from N. to S., he afterwards discovered that in large tracts of the South of Sweden the direction was from N.W. to S. E., and in others, particularly along the coasts of Norway, from N. E. to S. W.; all these facts being recorded on a map, which is a most valuable document. Since Sefstrom's work was published, M. Böhtlingk, a young Russian naturalist of great promise, but, alas! prematurely carried to the grave, extended his researches to the northern territories of Russia. Observing that the dominant direction of the scratches in parts of the governments of Olonetz and Archangel was from N. to S., and that along the edges of the Bothnian Gulf their course was from W. to E., he passed the summit level of Russian Lapland, and found that there the drift had no longer been transported from N. to S., or from N. W. to S. E., on the contrary, from S. E. to N. W.; or, in other words, the blocks of Lapland had been carried northwards into the shores of the Polar Sea. In a recent letter to Mr. Lyell, read before this Society, Professor Nordenskiöld has accurately recorded phenomena of this class observed by him in Finland, and he shows that there the blocks and striæ proceed from N.N.W. to S. S. E. See Taylor's Scientific Memoirs, vol. iii. p. 81. The theory of Sefström and his followers. is, that a great flood, transporting gravel, sand, and boulders, was impelled from the north over pre-existing land, and that the deviations from the N. and S. direction are due only to various promontories by which the flood was deflected. So convinced was this author that with local aberrations all the transport throughout the whole of Europe had taken place from north to south, that he not only travelled over the whole of Germany, and saw nothing except materials streaming in the same direction, but even carried with him his northern drift into the Austrian and Bavarian Alps. I will not waste your time by pointing out the errors into which his hypothesis, though founded on data good within a limited radius, led this author. Every one who has studied the Alps (and the facts were well known before the days of glacial theories), is perfectly aware that the detritus on their flanks has been shot off eccentrically from the higher central masses. The observations indeed of Böhtlingk give the same result upon a very grand scale in the north, and explain what Sefström, with all his valuable labor, had left unknown, viz., that the Scandinavian mountains, as a whole, had produced exactly the same detrital result as the Alps, having poured off their detritus in all directions from a common centre, the northern chain differing only from that of central Europe, by the much wider range to which its blocks and boulders were transmitted. My own belief, gentlemen, as you know, has been, that by far the greatest quantity of boulders, gravel, and clay distributed over our plains, and occupying the sides of our estuaries and river banks, was accumulated beneath the waters of former days. Throughout large tracts of England we can demonstrate this to have been the case by the collocation of marine shells of existing species with far transported materials. It was the association of these testacea with foreign blocks in the central countries of England which first led me to attach a new and substantial value to that view of glacial action which had been so well advocated by Mr. Lyell before Professor Agassiz came forward with his great terrestrial and general theory. I am bound to say, that wide researches during the last two years have strongly confirmed my early views.* could not travel, in the autumn of the year 1840, around the shores of the Highlands of Scotland, without being convinced that the *See Silurian System, p. 536. I terrace upon terrace, presented on the sides of some of the great valleys, and often high up on the sea-ward hills of the bays opening out to the ocean, were nothing more than the bottoms of former seas and estuaries which had been successively desiccated. of the blocks had been transported, had been the bed of the Northern or glacial sea at the period of this transport. We then attempted to explain how the parallel striæ and polishing of the surface of rocks of unequal altitude was reconcilable with the I coincide, therefore, entirely with Mr. C. submarine action of ice, by supposing that Darwin in his very ingenious explanation of the ice floes and their detritus might be set the probable formation of the parallel roads in motion by the elevation of the Scandinaof Glen Roy (Phil. Trans., 1839, p. 39). vian continent, and the consequent breakSince then, that excellent observer has borne ing up of great glaciers on the northern out similar views in a paper read before our shores of a sea which then covered all the own Society. In this memoir, estimating flat regions of Russia; and we further stathe different changes of the sea and land, ted our belief, that the bottoms of these iceand showing to what extent the solid strata bergs, extending to great depths, must have were depressed, whose relative histories he every here and there stranded upon the thus reads off, he traces the shingle beds highest and most uneven points of the botfrom the edge of the sea, where they are in tom of the sea into which they floated; that process of formation, to considerable heights where the bottom was hard rock, the lower inland; and estimating how blocks were surface of the iceberg, like the lower surtransported from the great Cordillera with-face of a glacier, would grate along and in, or not long before the period of existing score and polish the subjacent mass; that sea shells, he explains the far-transported where the bottom consisted of tenacious boulders by their being carried to the ports mud or clay, the iceberg once fairly strandwhere they lie in vessels of ice. The melt-ed would be retained till it melted away, ing of these icebergs he conceives to have entirely or in part, whilst it would be more been the chief agent in forming such mass-frequently borne over sand-banks, on aces of clay, gravel, and boulders, as consti-count of their less resistance. In this mantute the "till" of Scotland; whilst the con-ner, we endeavored to explain not only the fusion and contortion of their imperfect scratches and polish of hard submarine rocks, strata is considered by him to be necessarily due to the grounding of icebergs in the manner formerly suggested by Mr. Lyell. To the same powerfully disturbing agent he attributes the general absence of organic remains in these deposits; and, lastly, he infers that it is much more probable that the great boulders were transported in icebergs detached from glaciers on the coast, than imbedded in masses of ice produced by the freezing of the sea. but also why large blocks are often found on former submarine hills, and why (in Russia at least) such blocks are more frequently associated with clay than sand. These views were indeed first expressed at the Glasgow meeting of the British Association, when I strove to reduce a large portion of the Alpine glacial theory to considerations depending upon the fact, that during the era of the dispersion of the large blocks, by far the greater portion of our continents were beneath the sea. แ M. de Verneuil and myself had previously brought before you some new results, aris Mr. Maclaren, to whom I have already ing from our first expedition to Russia. We adverted, has recently improved this view, endeavored to show the utter inapplicabil- by showing how the parallel scratches and ity of the Alpine glacial theory to vast re- grooves ranging from N. N. W. to S. S. E., gions of northern Russia, though the sur- and the dispersion of blocks in that direction, faces of the rocks are scored and polished, are reconcilable with the union of currents and far-travelled blocks occur throughout a from the N., set in action, as above suppos. wide area in isolated groups, because much ed, by a great polar elevation which acted of this detritus has travelled over extensive as a centre of dispersion ;" but, as the autracts of low country, from which it has thor adds, a broad current would also set ascended to levels higher than the sources continually eastward along the immersed reof its origin. Hence we inferred, that the gions included in the temperate zone; and onward persistent march (in many parts up-hence, he says, that when the icebergs were hill) of a body of glaciers, having a front of many hundred miles in extent, is irreconcilable with any imaginable subaerial action. On the other hand, it was proved, by the presence of sea shells of an arctic character, that the "terra firma" to which some drifting southwards from the poles, they would naturally be carried to the S. E. by a stream compounded of the two currents. After reasoning upon the wide application to which the view of floating iceberg action is capable, and how many of our present ter restrial appearances it will explain, Mr. | South Pole in almost open sea, Captain J. Maclaren adds, "Mr. Murchison's hypothe- Ross discovered, as he proudly says, "for sis, if adopted, does not exclude that of the honor of England," the southernmost Agassiz. On the contrary, it may be assum-known land, which he named Victoria, and ed, that while the glacial condition (which which he coasted for more than 8 degrees caused the great accumulation of ice in the of latitude. This land rises in lofty mounnorthern regions) continued, every mountain peaks, from 9,000 to 12,000 feet in tain chain, which then had an elevation of height, perfectly covered with eternal snow 2000 or 3000 feet above the sea, would be from which glaciers descend, and project encrusted with ice, perhaps as far south as many miles into the ocean, terminating in the latitude of 40°. Each of these would perpendicular lofty cliffs. The rocks which be on a small scale what the polar nucleus could be examined were of igneous origin, was on a great scale, a centre of dispersion." and near the extreme south point of his In the memoir upon Russia by M. de exploration, or in S. lat. 77° 32', long. 167Verneuil and myself, one observation, how- E., a magnificent volcano was seen in full ever, occurs, which has not found its way action, emitting flame and smoke at an altiinto the abstracts, and which, therefore, 1tude of 12,400 feet. Further progress to may advert to, as explaining why the rough the southward was then impeded by an detritus of mud, sand, clay, and boulders so enormous barrier of ice, or glaciers 150 feet very seldom contains marine remains. Such high, which stretched from W. N. W. to E. heaps are made up of materials, which we S. E., and which the bold seaman traced in consider to have been imbedded in a true continuity for 300 miles, to long. E. 1910 terrestrial glacier, and therefore, though 23', and lat S. 78°. That this barrier was a detached, and floated to a distance, they true glacier was inferred from the existence never could afford more than terrestrial de- of a very lofty chain of mountains behind it, tritus; and if to this be added the considera- the tops of which, as seen from the masttion of how the stranding of such masses heads, were estimated to be a degree of would destroy animals in the vicinity, as latitude to the south of the sea-face of this suggested by Darwin, we may rationally great wall of ice, at not more than half a conceive why so few shells have been dis- mile from which the soundings were at 318 covered in this coarse detritus, whilst we fathoms deep, and upon a bed of blue soft readily perceive why the stones impacted mud. Here, then, the geologist is presentin it should be scored and striated, and oftened with abundant matter for speculation. polished. Volcanoes in the midst of eternal polar snow Besides the great advancement of our and glaciers, with seaward faces as wide as knowledge of terrestrial magnetism, which some of the continental tracts, which, from at some future day may be connected with the striæ and polished on their surface, and our labors, the Antarctic expedition, under the distinguished navigator Captain James Ross, has, as might have been expected, thrown considerable light upon the glacial theory. A few years only have passed since the existence of an enormous mass of ice-clad land in the antarctic region, was announced by an American squadron of geographical research. This great icy tract, which was described as exhibiting hills and valleys, and even rocks upon its surface, has entirely disappeared in the short intervening time; for Captain Ross has sailed completely through the parallels of latitude and in the same longitude which it was said to occupy. As we cannot suppose that the American navigators were deceived by atmospheric phenomena, so must we believe that what they took for solid land, was one of the enormous accumulations of ice called packs," the great source of those enormous ice islands which periodically encumber the Southern seas. Continuing his progress towards the the wide dispersion of blocks and detritus, are supposed to have been affected by former terrestrial glacial action. Whilst, however, we have here the proof that existing glaciers advance some few miles into the sea, we are also informed that the ice ceases suddenly against an ocean 2000 feet deep, and thus we are led to conclude that many glaciers, which may formerly have extended themselves into the sea, had a length, the extent of which, whether like this antarctic example, or those which have been measured in the Alps, was proportioned to the altitude of the ancient mountains against which they rested. By the same reasoning we may infer that the stria and polish of rocks, or accumulation of coarse detritus, and large blocks which are only to be observed in places far beyond the limits that are now established between two mountains and their dependent masses of ice, cannot be due to the advance of former solid glaciers, but must rather be referred, as I have argued, to the floating away of |