kilometres to the north, he again found others nearly parallel to the first; and without having visited the intermediate region, or taking into account the stria which, in these countries, form considerable angles with those he had chosen, he concluded that one and the same grooving system (such is the kind of expression he employs), extended from 63d to 59th degree of latitude, and proceeded from the north to the south of Norway. The author gives a similar account of the striæ which present a similar orientation at Gefle, on the shores of the Gulf of Bothnia, and in the neighbourhood of Gothenburg, a town situate on the North Sea. This mode of proceeding appears to me altogether arbitrary; for we might quite as easily form other groups completely different from the first, and which rested on as slender grounds. Why, for example, should we not consider as forming part of the same system, the striæ running from NNW. to SSE., in the vicinity of Areskutan, in Norway, and those which cover Finland, inclining in the same direction? In order to justify the establishment of these different groups, it would be necessary to prove, first, that the striae running in the same direction, are the effect of a uniform and uninterruped agent, such as a current or other mass capable of leaving marks of its passage; now, this M. Durocher has not done. Neither does he allow himself to be arrested by the directions of striæ which intersect these different groups at angles more or less open. Thus, the prolongation of the great system running from NNW. to SSE., from lake Oestersund to lake Maelar, near Stockholm, that is to say, from 63d to 59th degree of latitude, is at a right angle with the direction of the striæ of the island of Gottland. The striæ running from the N. to S., in the south of Sweden, are intersected, under an angle of 45°, by those in the neighbourhood of Cimbrishamn. M. Durocher, besides, leaves out of his ten systems of erosions, all the striæ whose direction does not conveniently agree with them; those, for example, which radiate round the Suletimten group of mountains, in the lower part of the Sognefiord; those in the neighbourhood of Sneehætten, Ekesjoë, Wexioë, Carlskrona, Cimbrishamn, the island of Gottland, &c., and notwithstanding all these liberties, the author

concludes without saying a single word on the force of facts which demonstrate that it is not water which has grooved the striæ of which he speaks; for it would be necessary to admit ten currents, perfectly rectilinear, simultaneously or successively directed towards the four cardinal points, without deviating from a straight line; a supposition inadmissible and contrary to all that we know of the laws which regulate the courses of water, whatever may be their force or volume.

The extension in ancient times of the Scandinavian glaciers, easily explains the varied directions of the striæ in the different regions of the peninsula. Their very parallelism would be an objection against the glacial hypothesis, admitting of no reply. Let us, in the first place, examine this phenomenon in Switzerland, where it has been studied with the greatest care, and by individuals possessing the most profound knowledge of the progress and effects of glaciers now existing. In Switzerland, as in Sweden, the striæ assume the most varied directions; it is easy to account for this. The plain which separates the Alps and the Jura, was formerly filled with glaciers, which descended by the principal basons of rivers, whose source is in the Alps; the Arve, Rhone, Aar, Reuss, Limmat, and Rhine. But each of these glaciers, carrying along with it the rocks which characterise it, had a different direction. Thus, while the glacier of the Rhone formed striæ in the Valais, between Sion and Martigny, running from ENE. to WSW., the ancient glacier of the Rhine passed over the moutonnéed rocks, which bear the ruins of Baerenburg, near Andeer in the Grisons, in the direction from SW. to NE.; and the glacier of Val-Montjoie grooved the polished rocks in the neighbourhood of NantBourant, at the foot of Col du Bonhomme, in the direction from SSE. to NNW. Nay, more; the direction of the striæ engraved by a glacier is not the same at different parts of its progress. In the environs of St Maurice, for example, the glacier of the Rhone has left striæ on the limestone, running from SE. to NW., while above Vevay, the gompholite is striated nearly in the direction from E. to W. At the mouth of the valley of Chamonix, in front of the village of Ouches,

the glacier of the Arve has formed striæ running from ESE. to WNW.; while, on issuing from the valley, we find, above the gorge of Montets, furrows many metres in length, the direction of which is from SSE. to NNW. Besides these facts, the striæ traced by the tributary of a glacier often cut the striæ engraved by the principal glacier under very wide angles. Thus, the glacier of Argentière, which descended by the Col de Salvent into that of the Rhone, has left, as the marks of its passage, striæ almost perpendicular to those of the latter. The furrows of the valley of Urbach cut those of the valley of Hasli, &c. &c.

I could multiply these examples, but I prefer to derive some instances from existing glaciers, in order to avoid the objection of some of the opponents of the ancient extension of the Swiss glaciers, who deny, notwithstanding the identity of the facts, the glacial origin of the striæ found in the plain between the Alps and the Jura. Let us conceive, for an instant, that the glacier of the Aar, or the Mer de Glace of Chamonix had disappeared. We would find in the valley they occupied, longitudinal striæ traced by the principal glacier, and transverse striæ formed by the tributary glaciers which cut the first under angles more or less acute. We would observe ascending striæ at the contraction of the valleys, and striæ crossing each other at the point where the two glaciers met; in a word, all that exists on a large scale in the Swiss plain and in Scandinavia. The phenomena and the explanation would be the same, only they would apply to a greater surface of country.

Accordingly, in the plains of Switzerland, as in those of Scandinavia, the striæ are found running in various directions; but in Sweden, as in Helvetia, these striæ are identical in every respect with those engraven by existing glaciers; and I do not think that we can, consistently with good logic, ascribe to one agent effects identical with those which an agent totally different produces every day under our own eyes. In order to complete the proof that M. Durocher's system is arbitrary and fruitful in erroneous consequences, let us apply it for an instant to Switzerland. We find on the southern shores of the lake of Brienz, striæ running from NE. VOL. XLIII. NO. LXXXV.-JULY 1847.

H

to SW. In the Valais, there are striæ nearly in the same direction, such as we again encounter in the valley of Chamonix, between Prieuré and the village of Ouches. According to M. Durocher's principles, all these striæ having the same orientation are united, and form a system of erosion, which, commencing in the Oberland, passes above the high chain of the Bernese Alps, crosses the Col de Balme, and extends to the foot of Mont Blanc; while, in reality, these striæ belong to three different glaciers; that of the Aar, that of the Rhone, and that of the Arve, which had nothing in common with each other, excepting that their directions were parallel at one point of their progress. According to this view of the subject, we should be forced, in order to be consistent, to consider the striæ lying in the same direction in the Alps, Vosges, and Pyrenees, as forming part of one system of erosion, over a space of four degrees of latitude, like that which many of M. Durocher's systems of striæ comprehend; while the latest evidence goes to prove that these stria have been engraved by glaciers descending from mountains into valleys, and not by a general agent proceeding from the north to the south, or from the east to the west.

Faithful to his principle of assuming the direction of the striæ as the sole guide in studying the line of route followed by the agent which traced them, an observer, proceeding on this method, would be forced to regard the furrows formed by a principal glacier, and those made by its tributaries, as belonging to different systems. In the valley occupied by the glacier of the Aar,* such a geologist would consider the striæ directed from west to east which this glacier has engraved under our eyes, as forming part of one system, while those of its tributaries, the glaciers of Thierberg, Silberberg, Grünberg, and Zinkenstock, which cut the former at right angles, more or less obtuse, he would regard as belonging to another system.

The plan followed by M. Durocher appears to me, therefore, erroneous, whether we apply it to the hypothesis of gla

* See the plan of the glacier of the Aar, Bulletin de la Société Geologique, 2d eries, t. iii., Pl. V., fig. 12. Meeting of 2d March 1846.

ciers, or to that of currents; for, in either case, we could not take the direction of the striæ as the only indication of the route taken by the agent which traced them, without taking into account all the other marks which might serve to make us acquainted with this direction. The problem is not beyond the means of solution, for M, A. Guyot has figured upon the map the space occupied by the different glaciers which formerly covered the plain lying between the Alps and the Jura. But, besides the direction of the striæ, he has taken into account the mineralogical nature of the transported rocks, their mode of dispersion, whether in a sporadical state, or in the form of lateral, median, or terminal moraines. He has followed these materials from the point of their departure in the Alps to their point of arrival in the Jura, and he has thus been enabled to circumscribe the domain of each glacier with as much accuracy as we can trace the limits of a superficial formation.*

Characters of the Transported Deposits in the north of Europe. In the flat country, this formation presents itself sometimes

* In his first memoir, M. Durocher had ascribed the sinuous canals, ramified and anastomosing with each other, which he had seen on the shores of the sea, to diluvian currents.* In the present, he remarks on the contradictions in the explanations which have been given of them by MM. Agassiz,† Escher de la Linth, P. Schimper,§ and myself. Now, all the four of us have ascribed the sinuous and anastomosing canals observed by M. Durocher to the action of water; only MM. Agassiz and Escher have considered the striæ engraved in the interior of these canals as the striæ of glaciers. M. Schimper ascribes them to the action of waves. For myself, I have not pronounced an opinion on the origin of these striæ, which were known to me, neither by specimens, nor detailed description, nor by accurate drawings. Accordingly, in my first reply,

I have not spoken of these striæ, and, in my second, I have expressed myself thus: "With the rest of M. Durocher's argument, supposing what I have not said, namely, that the striæ engraved in the interior of sinuous canals have been produced by glaciers, I shall not occupy myself." It will thus be seen that we agree as to the origin of these canals, only M. Schimper differs from MM. Agassiz and Escher in the explanation of one of the details, the striæ in their interior.

* See the form of these sinuous canals, Bulletin de la Société Geologique, 2d series, t. iii. Pl. I., figs. 1, 5, and 8; that of the striæ of glaciers, Pl. II., figs. 3, 4, 5, and 6. + Comptes Rendus de l'Academie des Sciences, t. xxi., p. 133. 15th Dec. 1845. ↑ Bulletin de la Société Geologique, 2d series, t. iii., p. 236. 19th Jan. 1846. Comptes Rendus de l'Academie des Sciences, t. xxii., p. 43-5. 5th Jan. 1846. Bulletin de la Société Geologique, 2d series, t. iii., p. 111. 15th Dec. 1845.