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carry their children over a certain road by the valley of Vieseh, across the Alps, to be baptized at Grindelwald, on the farther side of the glaciers of Aletsch and Vievh. I could not understand this statement, for no such road exists, or could be conceived possible at present; nor was there any knowledge of it among the guides, intimate as they are with every feature of the region. Impressed, however, with the idea that there must be some foundation for the statement, I carefully examined the ground, and, penetrating under the glacier of Aletsch, I actually found, a number of feet below the present level of the ice, the paved road along which these hardy people travelled to church with their children, and some traces of which are still visible. It h.i» been almost completely buried, although here and there it reappears; but at this day it is completely impassable for ordinary travel.
Evidence of a like character is found^ in a number of facts cited by Venetz in his celebrated paper upon the variations of temperature in the Swiss Alps, drawn from the parish and commune registers of the Canton of Valais. Among these are acts concerning the right to roto^ which are now cither entirely hidden by ice, or rendered nearly useless by the advance of the glacier, a lawsuit respecting the use of a forest which no lomger exists, but the site of which is covered by a glacier, and other records of a similar character. The only document, so far as I know, previous to this century, which furnishes the means of delineating with any accuracy the former boundary of a glacier, is a topographical plan of the environs of the Grimsel, including the extremity of the Aar, making a part of Altmann's work upon the Alps. In 1740, Kapeler, a physician of Lucerne, undertook a journey to the mountains of the Aar, to visit certain crystal grottos, now well known, but then recently discovered. He prepared a map of these grottos and their vicinity, in which they are represented as being situated at some distance from the extremity of the glacier,
the lower end of which is now considerably beyond them.*
But to return to the glacier of the Rhone." Wo can detect the sequence and relative ago of its ancient moraines, not only by their position with reference to each other and to the present glacier, but also by their vegetation. The older ones have a mature vegetation; indeed, some of the largest trees of the valley stand upon the lower moraines, while those higher up, nearer the glacier, have only comparatively small trees, and the more recent ones are almost bare of vegetation. Moreover, we do not lose the track of the great glacier of the Rhone even when we have followed its ancient boundaries to the shores of the Lake of Geneva; for along its northern and southern shores we can follow the lateral moraines marking the limits of the glacier which once occupied that crescent-shaped depression now filled by the blue waters of the lake.
M. de Charpunticr was the first geologist who attempted to draw the outlines of the glacier of the Rhone during its greatest extension, when it not only filled the basin of the Lake of Geneva, but stretched across the hilly plain to the north, reached the foot of the Jura, and even rose to a considerable height along the southern slope of that chain of mountains. At that time the colossal glacier spread at its extremity liko a fan, extending westward in the direction of Geneva and eastward towards Soleurc.t The very minute and extensive investigations of Professor A. Guyot upon the erratic boulders of Switzerland have not only confirmed the statements of M. de Charpentier, but even shown that the northeastern boundary of the ancient glacier of the Rhone was more
* This map, with nil its details and measurements, is reproduced (IM. V. fig. 1) in my "Systeme Glaciaire." It was accompanied by an explanatory paper in the form of > letter to Ainu.nut, then Profewor at Borne.
t M. de Charpentier has published a map of this ancient glacier in his "Essay upon th« . Glaciers and Erratics of the Valley of the Rhone."
extensive than was at first supposed. Other researches upon the ancient moraines along the shores of the Lake of Geneva, and in other parts of Switzerland, in which most geologists of the day took an active part, have made us as fully conversant with the successive outlines and varying extent of the principal glaciers ranging from the Alpine summits to the surrounding lowlands as we are with the glaciers in their present circumscription. But no one has done as much as Professor Guyot to add precision to these investigations. The number of localities, the level of which he has determined barometrically, with the view of fixing the ancient levels of all these vanished glaciers, is almost incredible. The result of all these surveys has been a distinct recognition of not less than seven gigantic glaciers descending from the northern and western slopes of the Alps to the adjoining hilly plains of Switzerland and France. It is most interesting to trace their outlines upon a recent map of those eonntries, but it requires that kind of intellectual effort of the imagination without which the most brilliant results of modern science remain an unmeaning record to us. Let us, nevertheless, try to follow.
The glacier of the Rhone, occupying the whole space between the Bernese and Valesian Alps, filled to overflowing the valley of the Rhone; at Martigny it was met by a large tributary from Mont Blanc, by the side of which it advanced into the plain beyond, filling the whole Lnke of Geneva, and covering the beautiful Canton de Vaud and parts of Fribourg, NeucTmtel, Berne, and Scleure, rising to the crest of the Jura, and in many points penetrating even beyond its outer range.
To the east of this, the largest of all the . ancient glaciers of Switzerland, we find the ancient glacier of the Aar, descending from the northern slope of the whole range of the Bernese Oberland. The glaciers that once filled the valley of Hasli, from the Grimsel to Meyringen, and those that came down from the Wet
terhorner, the Schreckhorner, (he Finster-Aarhorn, and the Jungfrau, through the valleys of Grindelwald and Lauturbrunnen, united in a common bed, the bottom of which was the present basin of the Lakes of Brientz and Thun. These were joined by the glaciers emptying their burden through the valley of the Kander. To these combined glaciers the formation of the terminal moraine of Thun must be ascribed. But before this had been formed, the glacier of the Aar, in its amplest extension, had also reached the foot of the Jura, without, however, spreading so widely as the glacier of the Rhone. Farther to the east Professor Guyot has traced the boundaries of three other colossal glaciers, one of which derived its chief supplies from the Alps of Uri, bringing with it all the tributaries which the main glacier coming down from the St. Gothard received right and left, in its course through the m valley of the Rcuss and the basins of the Lakes of Lucerne and Zug. The second, born in the Canton of Claris, followed mainly the present course of the Linth and the basin of the Lake of Zurich. Professor Kscher von der Linth has shownthat the lovely city of Zurich ia built upon a moraine, like Berne. Th% imagination shrinks from the thought that all the beautiful scenery of those countries should once have been hidden under masses of ice, like those now covering Greenland. The easternmost ancient glacier of Switzerland is that of the Rhine, arising from all the valleys from which now descend the many tributaries of that stream, spreading over the northeastern Cantons, filling the Lake of Constance, and terminating at the foot of the Suabian Alp. Next to the glacier of the Rhone, this was once the largest of those descending from the range of the Alps.
West of Mont Blanc Professor Guyot has traced the boundaries of two other distinct ancient glaciers; one of which, the glacier of the Arve, followed chiefly the course of the Arve, and, though discharging the icy accumulations from the western slope of Mont Blanc, was, as it were, only a lateral affluent of the great glacier of the Rhone. The other, the glacier of the Isere, occupied, to the south ;ind west of the preceding, the large triangular space intervening between the Alps and the Jura, in that part of Savoy where the two mountain-chains converge -and become united.
It would lead me too far, were I to describe also the course of the great ancient glaciers which descended from the southern slopes of the Alps into the plain of Northern Italy. Moreover, these boundaries are not yet ascertained with the same degree of accuracy as those of the northern and western slopes; though very accurate descriptions of sonic of them have been published, with illustrations on a large scale, by MM. Martins and Gastaldi, and of others by Professor Ramsey. I have myself examined only the upper part of that of the valley of Aosta.
The evidence concerning the ancient glaciers of the Alps, especially within the limits of Switzerland, is already so full that it affords ample means for a comprehensive general view of the subject . It is .frequently the case, that, when a stretch of time or space lies between us and a matter we have once studied more closely, it presents itself to us as a whole more vividly than when our nearness to it forced all its details upon our observation. In my present position, now that the lapse of many years separates me from my personal investigations of the ancient and modern glaciers, and I look back upon them from another continent, it teems to me that I have, as it were, a bird's-eye view of their whole extent; and I confess that this distant retrospect of the subject has been to me almost as fascinating as were the researches of my earlier years in the same direction. I wish that I could present it to the minds of my readers with something of the attraction it possesses for me. I trust, however, that I have made it plain to them that the great mountain - chain of the Alps has been 'a central axis from which immense
glaciers at one time descended in every direction, not only to its base, beyond which the lowlands extend in flat undulations, but to a greater or less distance over the adjoining plains; while it present they are confined to the higher valleys. • So far, then, notwithstanding the extraordinary difference in their dimensions, at the time they reached the Jura and the plain of Northern Italy, whun compared with what they are now, they seem directly connected with the Alps, and the mountains appear as their birthplace; so much so that the first attempts at a generalization concerning their origin started from the assumption that they must have been formed between the high ridges from which they seem to flow down. These facts, then the only ones known concerning a greater extension of the glaciers, naturally led to the views advocated by M. de Charpentier. My own theory was also at first, that the upheaval of the Alps must, in some way or other, have been connected with these phenomena. But it soon became evident to me that these views were inadequate to account for the former presence of extensive glaciers in other parts of Europe; and even within the range of the Alps there were insuperable objections to their final admission. If the ancient glaciers had been first formed among the highest mountains, and extended downwards into the plains, the largest and highest moraines ought to be the most distant, and to be formed of the most rounded masses; whereas the actual condition of the detrital accumulations is the reverse, the distant materials being widely spread, and true moraines being found only in valleys connected with groat chains of lofty mountains.
Again, all these moraines are within one another, — the most distant from the glacier to which they owe their origin encircling all those which are nearer and nearer to it within the same glacial basin. And as no glacier could reach to its farthest moraine without pushing forward all the intervening loose materials, it is self-evident that the outer nioramua were first formed, and those nearer the glacier subsequently, in the order in which they follow one another from the lower valleys to the higher levels at which alone glaciers exist at present. Translating these facts into words, we seo that the glaciers to which these ancient moraines owe their origin, must have been retreatmg gradually while the moraines were accumulating. But a glacier while uniformly retreating forms no high walls of loose materials around its edges and at its lower extremity; as it melts away, it only drops the burden of angular rocky fragments which it carries upon its back over the loose fragments above which it moves, and which it grinds to powder, or to sand, or to rounded pebbles, in its progress. It is only where the glacier remains stationary for a longer or shorter period that large terminal moraines can accumulate; and they are generally found in such places in the valleys of the Alps as would naturally determine the lower limit of a glacier for the time being. There is no possibility of escaping the conclusion that the ancient glaciers must have begun that series of oscillations to which the accumulation of the moraines is to be ascribed, at a time when ice-fields already occupied the whole area which they have covered during their greatest extension. After we shall have seen how many centres ,of dispersion of erratic boulders existed in the northern hemisphere, similar to .that of the Alps, we may perhaps be able to form some idea of the manner in which these ice-fields originated and .gradually vanished.
Sojtie investigators have been inclined to explain the presence of boulders, moraines, drift, and the like phenomena, by the action of water. But even if we could believe that rivers had brought along with them such masses of rock, and deposited them where they are now . found, the regularity in the distribution of the materials disproves any such theory. In the lateral moraines of the Lake of Geneva we have a striking illustration of this apparently systematic division of
the loose materials; for the northeastern moraines of that glacial basin contain rocks belonging exclusively to the northern side of the valley of the Rhone, while the moraines on the southern shore of the lake consist of rocks belonging to its-southern side. Indeed, rivers, so far from building up moraines, have often partially destroyed them. We find various instances of moraines through which a river runs, having worn for itself a passage, on either side of which the form of the moraine remains unbroken. In the valley of the Rhone there are villages built on such moraines, as, for instance, Viesch, with the river running through their centre.
But if we need further confirmation of the fact that these accumulations on either side of this and other Swiss lakes are ancient lateral moraines, we have it in their connection with walls of a like nature at their lower end, where we find again transverse moraines barring their outlet, and also in the continuity of long trains of fragments of similar rocks extending side by side across wide plains for great distances without mixture. From the beginning of my investigations upon the glaciers, I have urged these two points as most directly proving their greater extension in former times, and more recent researches constantly recur to this kind of evidence. All our lakes would be filled with loose materials, had their basins not been sheltered by ice against the encroachments of river-delKJsits during the transportation of the erratic boulders to the farthest limits of their respective areas; and all the continuous trails of rocks derived from the same locality would have been scattered over wide areas, had they not been carried along, in unyielding tracks, like moraines. On a small scale the waters of the Rhone and of the Arve recall to this day such a picture. There are few travellers in Switzerland who have not seen these two rivers, wheru they flow side by sidu, meeting, but not mingling, at the southern extremity of the lake, the diflerent color of their water marking the two parallel currents. In old times, when the glaciers filled all the valleys at the base of Mont Blanc, and to the east of it, uniting in the valley through which now runs the River Rhone, the glacier of the Arve came down to mfet the ice from the valley of the Rhone, in the same manner as the Ri ver A rve now comes to meet the waters of the Rhone where they rush out from the southern end of ilu- lake.
This would be the proper place to consider the formation of the -lakes of Switzerland, as well as their preservation by the agency of glaciers. But this subject is so intricate, and ban already given rise to so many controversies which could not be overlooked in this connection, that I prefer to pass it over altogether in silence. Suffice it to say that not only are most of the lakes of Switzerland hemmed in by transverse moraines at their lower extremity, but the lakes of Upper Italy, at the foot of the Alps, are barred in the same way, as are also the lakes of Norway and Sweden, and some of our own ponds and lakes. Strange as it may Kem to the traveller who sails under an Italian sky over the lovely waters of Como, Maggiore, and Lugano, it is,' nevertheless, true, that these depressions were once filled by solid masses of ice, and that the walls built by the old glaciers still block theirsouthern outlets. Indeed, were it not for these moraines, there would be comparatively few lakes either in Northern Italy or in Switzerland: The greater part of them have such a wall built across one end; and but for this masonry of the glacier, there would have been nothing to prevent their waters from flowing out into the plain at the breaking up of the ice-period. We should then have-had open valleys in place of all these sheets of water which give such diversity and bwvity to the scenery of Northern Italy and Switzerland, or, at least, the lakes would be much fewer and occupy only the deeper depressions in the hard rocks. Such being the evidences of the former extent of the glaciers in the plains, what do the mountain-summits tell us of their height and depth */ for here, also,
they have left their handwriting on the wall. Kvery mountain-side in the Alps is inscribed with these ancient characters, recording the level of the ice in past times. Here and there a ledge or terrace on the wall of the valley has afforded support for the lateral moraines, and wherever such an accumulation is left, it marks the limit of the ice at some former period. These indications are, however, uncertain and fragmentary, depending upon projections of the rocky walls. But thousands of feet above the present level of the glacier, far up toward their summits, we find the sides of the mountains furrowed, scratched, and polished in exactly the same manner as the surfaces over which the glaciers pass at presentThese marks are as legible and clear to one who is familiar with glacial traces as are hieroglyphies to the Egyptian scholar; indeed, more so, — for he not only recognizes their presence, but reads their meaning at a glance. Above the line at which these indications cease, the edges of the rocks are sharp and angular, the surface of the mountain rough, unpolished, and absolutely devoid of all those marks resulting from glacial action. On the Alps these traces arc visible to a height of nine thousand feet, and across the whole plain of Switzerland, as I have stated, one may trace the glaciers by their moraines, by the masses of rock they have let fall here and there, by the drift they have deposited, to the very foot of the opposite chain, where they have dropped their boulders along the base of the Jura. Ascending that chain, one finds the grooved, polished, and scratched surfaces to its summit, on the very crest of which boulders entirely foreign to the locality are perched. Follow the range down upon the other side and you find the same indications extending into the plains of Burgundy and France beyond.
With a chain of evidence so complete, it seems to me impossible to deny that the whole space between the opposite chains of the Alps and the Jura was once filled with ice; that this mass of ice com