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and eastern shore, ranging from the mouth of the Elbe by Cracow into the very heart of European Russia at Voroneje-thence varying N.E. to the inosculation of the Timan and Ural chains, and following the western slope of the former to the Arctic Ocean.
To such waves of translation our authors ascribe the transmission of the great mass of the more rolled drift-but yet they are far from excluding the action of glaciers, where such could have existed and been available ; thus they conceive that the transport of the larger rectangular blocks of granite lodged over the plains and often on the summits of ridges in Prussia and Russia, may most readily be accounted for—inasmuch as the highest and coldest regions of Scandinavia may have been, as they still are, the seat of glaciers whose feet extended to the former sea coast. From these masses of ice may have been detached from time to time in the form of floats or icebergs, which may have carried off loads of detrital blocks (in the manner of those observed by Sir J. Ross in his Antarctic voyage) to the distance of hundreds of miles from the source of their origin. These icebergs would naturally be arrested by sub-marine elevations, become dissolved, and discharge their load of fragments there. We have premised this theoretic explanation of the phenomena, because it is so very natural and applicable that it is difficult to describe the facts themselves otherwise than in terms which must suggest it: but one of Sir R. Murchison's numerous diagrams so clearly explains the matter, that we must indulge ourselves by a copy of the cut. The boulders represented occur near Old Upsala, on a hill about 100 feet above the level of the surrounding country. K
We shall now proceed to a hasty and cursory survey of the evidence confirming the author's theory, referring, however, every reader who wishes for complete satisfaction to the original chapters (xx. and xxi.), where he will find every word worthy of attentive perusal. In the first place, we should observe that beds of marine shells undistinguishable from those of the neighbouring seas, have been found at Upsala in Sweden, 30 miles inland from the mouth of the Gulf of Bothnia, and in many places nearer the coasts of that country, and of Norway; in the north-west of Russia at the confluence of the Vaga and Dvina, 150 miles above the mouth of the latter at Archangel in the White Sea. These most recent marine deposits form the basis on which the drift of which we have been speaking is scattered, proving their subaqueous accumulation. Finally, similar marine shells have been found (as appears by a postscript in August, 1845) absolutely under the northern drift upon the Silurian limestone of Esthonia.
If we examine the parent source of these debris in Scandinavia, we shall find the surface of the crystalline rocks very commonly
a. Ancient submarine hill composed of sea sand and clay, with Tellina Baltica, and now forming the land called Tun-os.
- direction of the current.
which could possibly maintain glaciers ever could have esisted. Finland, most remote from any mountains, and where no heights glaciers ;-yet these are found in the lowest tracts of Sweden and bling those which have been considered as the true moraines of shaped masses of the accumulated drift, there called osars, resemferred to as proofs of glacial action; and we find long ridgemarked by those striated scratches which have so often been re
In this enlarged plan, the converging terraces (cc) of the section are represented to the left, the line of blocks (S) to the right. Our authors have shown that large masses of drift impelled forward, would, by the effect of their weight, cause the lowest pebbles and sand to scratch the subjacent rocks, just in the same manner as the pressure of incumbent and advancing glaciers would have done.
These striæ are generally disposed in lines diverging from the higher mountain group of Scandinavia as a centre, and the courses of the drift form immense trainées, often prolonged nearly a thousand miles from the parent rock, to which, however, following up these lines of drift, we always trace them.
These drift-lines, on account of this radiation, form a centre range through Germany and Prussia, north and south. Through Russia the average direction is from north-west to south-east, inclining of course more to the south on the confines of Poland, and becoming due west in the White Sea. On the north coasts of Scandinavia the lines are said to range northwards; and from the south-western extremity of the peninsula the drift has been carried in the direction of our own shores to Norfolk and Yorkshire.
The abrasion and denudation of the rocks against which these currents have swept indicate in like manner their direction and force. This is strikingly exhibited in the thousand islets, or rather insulated rocks, studding the entrance of the Gulf of Bothnia. There the drift-course being from north to south, the north side of every low islet exposes a face worn down, rounded, polished, and striated, as if by a tremendous macerating weight, whilst every south face retains its original abrupt and rough contour. A similar abrasion of the face of every projecting hill exposed to the force and direction of the current is found elsewhere, and generally, to prevail. Here we find ourselves unable to employ terms that will not of themselves suggest the nature of the agents producing such effects.
Where such projecting rocks have interposed to check the course of the current, we find the drift swept away from their exposed face, and accumulated in a long tail, as it were, under their lee, as by the divaricated currents sweeping round to meet beyond.
The abrasion in Sweden has exerted its most destructive power in denuding the Silurian rocks which appear to have once covered very extensively the gneiss in the lowland tracts, leaving only detached outliers; and our authors inform us that so much Silurian detritus has been swept off from hence, and transported to the low grounds of Germany, that if it could be swept back again to its native site, it would to a great extent fill up the breaches thus occasioned. Where the waves of translation have swept over the carboni
ferous zone of North-Western Russia, they have in like manner carried off with them, to the south-east, quantities of its fragments.
The boulders of the drift diminish in size as the distance from their original source increases: thus, around St. Petersburg, we often find granite and greenstone blocks of nine or ten feet in diameter; about Moscow, six hundred miles from their native position, they seldom exceed three feet. The larger blocks are commonly little worn and subangular, and they are generally found lodged on higher plateaux; and especially when the soil on these is argillaceous, low spaces and sandy tracts are often quite free from them. It is attributed to their conveyance by icebergs, which may have been checked by elevated submarine banks, and detained by the tenacious clay, while they would easily drift over looser sand.
The space or bottom over which they have been distributed forms generally an inclined plane, or rather undulating surface, rising from its Baltic or northern border to its southern limits, on the coast line of the hypothetical sea through which we suppose the waves of translation, which have thus carried the drift, to have been propagated. Mr. Hopkins has demonstrated the competency of such means to accomplish this; while, on the other hand, Professor James Forbes, after an assiduous personal survey of the Alpine glaciers, has proved, by exact experiments on the movements of their ice, that they never can advance, except by their gravity, on surfaces inclining downwards.
The drift is often accumulated on long and elevated ridges, like the pebble banks in our present seas.
The distribution of the drift along its southern terminal limit is exactly such as would have taken place if we conceive this to have been an ancient line of coast. Where loftier hills would have formed promontories advancing into that sea, the boundary of the drift has formed curves around their base; and where opening valleys would represent deep bays, into these the drift has swept, and covered them by its accumulations, as exhibited in the general map.
We should be sorry under any circumstances to mix up anything like temporary politics with a scientific discussion, otherwise we must have paused at some length on our authors' most striking description of that singular, unique, superficial deposit the black earth, or tchornozem, which covers such enormous tracts in Central and Southern Russia. We shall soon, we fear, be but too familiar with the pretty word Tchornozem; for this precious humus requires absolutely no manure, and there is enough of it to produce countless millions of tchetvériks of most laudable wheat; and a vast proportion of the inexhaustible area is so situated, both in a geographical and an economical sense, that a very moderate bonus in expectation is likely to bring its capabilities into eager requisition. The stratum varies from five or six feet in depth to fifteen and twenty, and Murchison speaks of the whole taken together as 'occupying the centre of a trough large as an European empire' (p. 558). We must also, and more reluctantly, pass by his account of the remarkably incoherent condition of the subsoil, which, combined with the changes of an extreme climate, produces such extraordinary degradation and waste; nor shall we now touch upon other modern variations in the physical outlines of this vast region, as dependent on the action of ice in rivers and lakes, or the tremendous débâcles of its spring season. In short, we must wind up our survey of this colossal labour of modern geology. We have, we hope, sufficiently expressed our opinion of the distinguished merit of the work, and no peroration is called for. Our great aim has been to give, as far as it was practicable, a real, not a nominal review; but most imperfect after all such must be without due reference to the admirable maps, sections, woodcuts, and pictorial views, which actually place ihe framework of Russia before our eyes, and bespeak the splendid liberality of those who have prepared and presented these magnificent volumes. So, in taking leave of our geological triumvirate, we shall simply copy the words with which their chief closes his Introductory Chapter :
"A few years ago, when unable to indicate the first created animals, or the exact relative places occupied by some of the earliest formations, we were compelled to trace the sequence downwards by commencing with deposits previously analysed, proceeding thence to those of anterior date ; but now, having learnt to decipher the very first letters in the long records of animal life, we assume a more distinct position as historians, and exhibit in their natural order the successive organic features which appear in the stony legend of the carth, from their earliest dawn to the present condition of the planet.
In a word, after a patient study of the types of palæozoic life, we can now fearlessly assert that the geological history or sequence of the earliest races of fossil animals is firmly established. Its truth is sustained by the display of forms which mark the period when the first vestiges of life can be discovered, as well as the following successive creations; and thus whilst, with the exception of one sacred record, we can truly say that the origin of the greatest empires of man is buried in fable and superstition, the hard and indelible register, as preserved for our inspection in the great book of ancient Nature, is at length interpreted and read off with clearness and precision.'