Part 4

103. And the ice itself may be employed to concentrate them. With an ice-lens in the polar regions Dr. Scoresby has often concentrated the sun's rays so as to make them burn wood, fire gunpowder, and melt lead; thus proving that the heating power is retained by the rays, even after they have passed through so cold a substance.

104. By rendering the rays of the electric lamp parallel, and then sending them through a lens of ice, we obtain all the effects which Dr. Scoresby obtained with the rays of the sun.

§ 12. _The Source of the Arveiron. Ice Pinnacles, Towers, and Chasms of the Glacier des Bois. Passage to the Montanvert._

105. Our preparatory studies are for the present ended, and thus informed, let us approach the Alps. Through the village of Chamouni, in Savoy, a river rushes which is called the Arve. Let us trace this river backwards from Chamouni. At a little distance from the village the river forks; one of its branches still continues to be called the Arve, the other is the Arveiron. Following this latter we come to what is called the "source of the Arveiron"--a short hour's walk from Chamouni. Here, as in the case of the Rhone already referred to, you are fronted by a huge mass of ice, the end of a glacier, and from an arch in the ice the Arveiron issues. Do not trust the arch in summer. Its roof falls at intervals with a startling crash, and would infallibly crush any person on whom it might fall.

106. We must now be observant. Looking about us here, we find in front of the ice curious heaps and ridges of débris, which are more or less concentric. These are the _terminal moraines_ of the glacier. We shall examine them subsequently.

107. We now turn to the left, and ascend the slope beside the glacier. As we ascend we get a better view, and find that the ice here fills a narrow valley. We come upon another singular ridge, not of fresh débris, like those lower down, but covered in part with trees, and appearing to be literally as "old as the hills." It tells a wonderful tale. We soon satisfy ourselves that the ridge is an ancient moraine, and at once conclude that the glacier, at some former period of its existence, was vastly larger than it is now. This old moraine stretches right across the main valley, and abuts against the mountains at the opposite side.

108. Having passed the terminal portion of the glacier, which is covered with stones and rubbish, we find ourselves beside a very wonderful exhibition of ice. The glacier descends a steep gorge, and in doing so is riven and broken in the most extraordinary manner. Here are towers, and pinnacles, and fantastic shapes wrought out by the action of the weather, which put one in mind of rude sculpture. Annexed is a sketch of an ice-pinnacle. From deep chasms in the glacier issues a delicate shimmer of blue light. At times we hear a sound like thunder, which arises either from the falling of a tower of ice, or from the tumble of a huge stone into a chasm. The glacier maintains this wild and chaotic character for some time; and the best iceman would find himself defeated in any attempt to get along it.

109. We reach a place called the Chapeau, where, if we wish, we can have refreshment in a little mountain hut. We then pass the _Mauvais Pas_, a precipitous rock, on the face of which steps are hewn, and the unpractised traveller is assisted by a rope. We pursue our journey, partly along the mountain side, and partly along a ridge of singularly artificial aspect a _lateral moraine_. We at length face a house perched upon an eminence at the opposite side of the glacier. This is the auberge of the Montanvert, well known to all visitors to this portion of the Alps.

110. Here we cross the glacier. I should have told you that its lower part, including the broken portion we have passed, is called the Glacier des Bois; while the place that we are now about to cross is the beginning of the Mer de Glace. You feel that this term is not quite appropriate, for the glacier here is much more like a _river_ of ice than a sea. The valley which it fills is about half a mile wide.

111. The ice may be riven where we enter upon it, but with the necessary care there is no difficulty in crossing this portion of the Mer de Glace. The clefts and chasms in the ice are called _crevasses_; we shall make their acquaintance on a grander scale by and by.

112. Look up and down this side of the glacier. It is considerably riven, but as we advance the crevasses will diminish, and we shall find very few of them at the other side. Note this for future use. The ice is at first dirty; but the dirt soon disappears, and you come upon the clean crisp surface of the glacier. You have already noticed that the clean ice is white, and that from a distance it resembles snow rather than ice. This is caused by the breaking up of the surface by the solar heat. When you pound transparent rock-salt into powder it is as white as table-salt, and it is the minute fissuring of the surface of the glacier by the sun's rays that causes it to appear white. _Within_ the glacier the ice is transparent. After an exhilarating passage we get upon the opposite lateral moraine, and ascend the steep slope from it to the Montanvert Inn.

§ 13. _The Mer de Glace and its Sources. Our First Climb to the Cleft Station._

113. Here the view before us is very grand. We look across the glacier at the beautiful pyramid of the Aiguille du Dru (shown in our frontispiece); and to the right at the Aiguille des Charmoz, with its sharp pinnacles bent as if they were ductile. Looking straight up the glacier the view is bounded by the great crests called La Grande Jorasse, nearly 14,000 feet high. Our object now is to get into the very heart of the mountains, and to pursue to its origin the wonderful frozen river which we have just crossed.

114. Starting from the Montanvert with, the glacier below us to our left, we soon reach some rocks resembling the Mauvais Pas; they are called _les Fonts_. We cross them and reach _l'Angle_, where we quit the land for the ice. We walk up the glacier, but before reaching the promontory called Trélaporte, we take once more to the mountain side; for though the path here has been forsaken on account of its danger, for the sake of knowledge we are prepared to incur danger to a reasonable extent. A little glacier reposes on the slope to our right. We may see a huge boulder or two poised on the end of the glacier, and, if fortunate, also see the boulder liberated and plunging violently down the slope. Presence of mind is all that is necessary to render our safety certain; but travellers do not always show presence of mind, and hence the path which formerly led over this slope has been forsaken. The whole slope is cumbered by masses of rock which this little glacier has sent down. These I wished you to see; by and by they shall be fully accounted for.

115. Above Trélaporte to the right you see a most singular cleft in the rocks, in the middle of which stands an isolated pillar, hewn out by the weather. Our next object is to get to the tower of rock to the left of that cleft, for from that position we shall gain a most commanding and instructive view of the Mer de Glace and its sources.

116. The cleft referred to, with its pillar, may be seen to the right of the preceding engraving of the Mer de Glace. Below the cleft is also seen the little glacier just referred to.

117. We may reach this cleft by a steep gully, visible from our present position, and leading directly up to the cleft. But these gullies, or couloirs, are very dangerous, being the pathways of stones falling from the heights. We will therefore take the rocks to the left of the gully, by close inspection ascertain their assailable points, and there attack them. In the Alps as elsewhere wonderful things may be done by looking steadfastly at difficulties, and testing them wherever they appear assailable. We thus reach our station, where the glory of the prospect, and the insight that we gain as to the formation of the Mer de Glace, far more than repay us for the labour of our ascent.

118. For we see the glacier below us, stretching its frozen tongue downwards past the Montanvert. And we now find this single glacier branching out into three others, some of them wider than itself. Regard the branch to the right, the Glacier du Géant. It stretches smoothly up for a long distance, then becomes disturbed, and then changes to a great frozen cascade, down which the ice appears to tumble in wild confusion. Above the cascade you see an expanse of shining snow, occupying an area of some square miles.

§ 14. _Ice-cascade and Snows of the Col du Géant._

119. Instead of climbing to the height where we now stand, we might have continued our walk upon the Mer de Glace, turned round the promontory of Trélaporte, and walked right up the Glacier du Géant. We should have found ice under our feet up to the bottom of the cascade. It is not so compact as the ice lower down, but you would not think of refusing to call it ice.

120. As we approach the fall, the smooth and unbroken character of the glacier changes more and more. We encounter transverse ridges succeeding each other with augmenting steepness. The ice becomes more and more fissured and confused. We wind through tortuous ravines, climb huge ice-mounds, and creep cautiously along crumbling crests, with crevasses right and left. The confusion increases until further advance along the centre of the glacier is impossible.

121. But with the aid of an axe to cut steps in the steeper ice-walls and slopes we might, by swerving to either side of the glacier, work our way to the top of the cascade. If we ascended to the right, we should have to take care of the ice avalanches which sometimes thunder down the slopes; if to the left, we should have to take care of the stones let loose from the Aiguille Noire. After we had cleared the cascade, we should have to beware for a time of the crevasses, which for some distance above the fall yawn terribly. But by caution we could get round them, and sometimes cross them by bridges of snow. Here the skill and knowledge to be acquired only by long practice come into play; and here also the use of the Alpine rope suggests itself. For not only are the 'snow bridges often frail, but whole crevasses are sometimes covered, the unhappy traveller being first made aware of their existence by the snow breaking under his feet. Many lives have thus been lost, and some quite recently.

122. Once upon the plateau above the ice-fall we find the surface totally changed. Below the fall we walked upon ice; here we are upon snow. After a gentle but long ascent we reach a depression of the ridge which bounds the snow-field at the top, and now look over Italy. We stand upon the famous Col du Géant.

123. They were no idle scamperers on the mountains that made these wild recesses first known; it was not the desire for health which now brings some, or the desire for grandeur and beauty which brings others, or the wish to be able to say that they have climbed a mountain or crossed a col, which I fear brings a good many more; it was a desire for _knowledge_ that brought the first explorers here, and on this col the celebrated De Saussure lived for seventeen days, making scientific observations.

§ 15. _Questioning the Glaciers._

124. I would now ask you to consider for a moment the facts which such an excursion places in our possession. The snow through which we have in idea trudged is the snow of last winter and spring. Had we placed last August a proper mark upon the surface of the snow, we should find it this August at a certain depth beneath the surface. A good deal has been melted by the summer sun, but a good deal of it remains, and it will continue until the snows of the coming winter fall and cover it. This again will be in part preserved till next August, a good deal of it remaining until it is covered by the snow of the subsequent winter. We thus arrive at the certain conclusion that on the plateau of the Col du Géant _the quantity of snow that falls annually exceeds the quantity melted_.

125. Had we come in the month of April or May, we should have found the glacier below the ice-fall also covered with snow, which is now entirely cleared away by the heat of summer. Nay, more, the ice there is obviously melting, forming running brooks which cut channels in the ice, and expand here and there into small blue-green lakes. Hence you conclude with certainty that below the ice-fall _the quantity of frozen material falling upon the glacier is less than the quantity melted_.

126. And this forces upon us another conclusion: between the glacier below the ice-fall and the plateau above it there must exist a line where the quantity of snow which falls _is exactly equal_ to the quantity annually melted. This is the _snow-line_. On some glaciers it is quite distinct, and it would be distinct here were the ice less broken and confused than it actually is.

127. The French term _névé_ is applied to the glacial region above the snow-line, while the word _glacier_ is restricted to the ice below it. Thus the snows of the Col du Géant constitute the névé of the Glacier du Géant, and in part, the névé of the Mer de Glace.

128. But if every year thus leaves a residue of snow upon the plateau of the Col du Géant, it necessarily follows that the plateau must get annually higher, _provided the snow remain upon it_. Equally certain is the conclusion that the whole length of the glacier below the cascade must sink gradually lower, _if the waste of annual melting be not made good_. Supposing two feet of snow a year to remain upon the Col, this would raise it to a height far surpassing that of Mont Blanc in five thousand years. Such accumulation must take place if the snow remain upon the Col; but the accumulation does _not_ take place, hence the snow does not remain on the Col. The question then is, whither does it go?

§ 16. _Branches and Medial Moraines of the Mer de Glace from the Cleft Station._

129. We shall grapple with this question immediately. Meanwhile look at that ice-valley in front of us, stretching up between Mont Tacul and the Aiguille de Léchaud, to the base of the great ridge called the Grande Jorasse. This is called the Glacier de Léchaud. It receives at its head the snows of the Jorasse and of Mont Mallet, and joins the Glacier du Géant at the promontory of the Tacul. The glaciers seem welded together where they join, but they continue distinct. Between them you clearly trace a stripe of débris (_c_ on the annexed sketch-plan); you trace a similar though smaller stripe (_a_ on the sketch), from the junction of the Glacier du Géant with the Glacier des Périades at the foot of the Aiguille Noire, which you also follow along the Mer de Glace.

130. We also see another glacier, or a portion of it, to the left, falling apparently in broken fragments through a narrow gorge (Cascade du Talèfre on the sketch) and joining the Léchaud, and from their point of junction also a stripe of débris (_d_) runs downwards along the Mer de Glace. Beyond this again we notice another stripe (_e_), which seems to begin at the bottom of the ice-fall, rising as it were from the body of the glacier. Beyond all of these we can notice the lateral moraine of the Mer de Glace.

131. These stripes are the _medial moraines_ of the Mer de Glace. We shall learn more about them immediately.

132. And now, having informed our minds by these observations, let our eyes wander over the whole glorious scene, the splintered peaks and the hacked and jagged crests, the far-stretching snow-fields, the smaller glaciers which nestle on the heights, the deep blue heaven and the sailing clouds. Is it not worth some labour to gain command of such a scene? But the delight it imparts is heightened by the fact that we did not come expressly to see it; we came to instruct ourselves about the glacier, and this high enjoyment is an incident of our labour. You will find it thus through life; without honest labour there can be no deep joy.

§ 17. _The Talèfre and the Jardin. Work among the Crevasses._

133. And now let us descend to the Mer de Glace, for I want to take you across the glacier to that broken ice-fall the origin of which we have not yet seen. We aim at the farther side of the glacier, and to reach it we must cross those dark stripes of débris which we observed from the heights. Looked at from above, these moraines seemed flat, but now we find them to be ridges of stones and rubbish, from twenty to thirty feet high.

134. We quit the ice at a place called the Couvercle, and wind round this promontory, ascending all the time. We squeeze ourselves through the _Égralets_, a kind of natural staircase in the rock, and soon afterwards obtain a full view of the ice-fall, the origin of which we wish to find. The ice upon the fall is much broken; we have pinnacles and towers, some erect, some leaning, and some, if we are fortunate, falling like those upon the Glacier des Bois; and we have chasms from which issues a delicate blue light. With the ice-fall to our right we continue to ascend, until at length we command a view of a huge glacier basin, almost level, and on the middle of which stands a solitary island, entirely surrounded by ice. We stand at the edge of the _Glacier du Talèfre_, and connect it with the ice-fall we have passed. The glacier is bounded by rocky ridges, hacked and torn at the top into teeth and edges, and buttressed by snow fluted by the descending stones.

135. We cross the basin to the central island, and find grass and flowers at the place where we enter upon it. This is the celebrated _Jardin_, of which you have often heard. The upper part of the Jardin is bare rock. Close at hand is one of the noblest peaks in this portion of the Alps, the Aiguille Verte. It is between thirteen and fourteen thousand feet high, and down its sides, after freshly-fallen snow, avalanches incessantly thunder. From one of its projections a streak of moraine starts down the Talèfre; from the Jardin also a similar streak of moraine issues. Both continue side by side to the top of the ice-fall, where they are engulphed in the chasms. But at the bottom of the fall they reappear, as if newly emerging from the body of the glacier, and afterwards they continue along the Mer de Glace.

136. Walk with me now alongside the moraine from the Jardin down towards the ice-fall. For a time our work is easy, such fissures as appear offering no impediment to our march. But the crevasses become gradually wider and wilder, following each other at length so rapidly as to leave merely walls of ice between them. Here perfect steadiness of foot is necessary a slip would be death. We look towards the fall, and observe the confusion of walls and blocks and chasms below us increasing. At length prudence and reason cry "Halt!" We may swerve to the right or to the left, and making our way along crests of ice, with chasms on both hands, reach either the right lateral moraine or the left lateral moraine of the glacier.

§ 18. _First Questions regarding Glacier Motion. Drifting of Bodies buried in a Crevasse._

137. But what are these lateral moraines? As you and I go from day to day along the glaciers, their origin is gradually made plain. We see at intervals the stones and rubbish descending from the mountain sides and arrested by the ice. All along the fringe of the glacier the stones and rubbish fall, and it soon becomes evident that we have here the source of the lateral moraines.

138. But how are the medial moraines to be accounted for? How does the débris range itself upon the glacier in stripes some hundreds of yards from its edge, leaving the space between them and the edge clear of rubbish? Some have supposed the stones to have rolled over the glacier from the sides, but the supposition will not bear examination. Call to mind now our reasoning regarding the excess of snow which falls above the snow-line, and our subsequent question, How is the snow disposed of. Can it be that the entire mass is moving slowly downwards? If so, the lateral moraines would be carried along by the ice on which they rest, and when two branch glaciers unite they would lay their adjacent lateral moraines together to form a medial moraine upon the trunk glacier.

139. There is, in fact, no way that we can see of disposing of the excess of snow above the snow-line; there is no way of making good the constant waste of the ice below the snow-line; there is no way of accounting for the medial moraines of the glacier, but by supposing that from the highest snow-fields of the Col du Géant, the Léchaud, and the Talèfre, to the extreme end of the Glacier des Bois, the whole mass of frozen matter is moving downwards.

140. If you were older, it would give me pleasure to take you up Mont Blanc. Starting from Chamouni, we should first pass through woods and pastures, then up the steep hill-face with the Glacier des Bossons to our right, to a rock known as the _Pierre Pointue_; thence to a higher rock called the _Pierre l'Échelle_, because here a ladder is usually placed to assist in crossing the chasms of the glacier. At the Pierre l'Échelle we should strike the ice, and passing under the Aiguille du Midi, which towers to the left, and which sometimes sweeps a portion of the track with stone avalanches, we should cross the Glacier des Bossons; amid heaped-up mounds and broken towers of ice; up steep slopes; over chasms so deep that their bottoms are hid in darkness.

141. We reach the rocks of the Grands Mulets, which form a kind of barren islet in the icy sea; thence to the higher snow-fields, crossing the _Petit Plateau_, which we should find cumbered by blocks of ice. Looking to the right, we should see whence they came, for rising here with threatening aspect high above us are the broken ice-crags[B] of the Dôme du Goûté. The guides wish to pass this place in silence, and it is just as well to humour them, however much you may doubt the competence of the human voice to bring the ice-crags down. From the Petit Plateau a steep snow-slope would carry us to the Grand Plateau, and at day-dawn I know nothing in the whole Alps more grand and solemn than this place.

[B] Named _séracs_ from their resemblance in shape and colour to an inferior kind of curdy cheese called by this name at Chamouni.

142. One object of our ascent would be now attained; for here at the head of the Grand Plateau, and at the foot of the final slope of Mont Blanc, I should show you a great crevasse, into which three guides were poured by an avalanche in the year 1820.

143. Is this language correct? A crevasse hardly to be distinguished from the present one undoubtedly existed here in 1820. But was it the identical crevasse now existing? Is the ice riven here to-day the same as that riven fifty-one years ago? By no means. How is this proved? By the fact that more than forty years after their interment, the remains of those three guides were found near the end of the Glacier des Bossons, many miles below the existing crevasse.

144. The same observation proves to demonstration that it is the ice near the _bottom_ of the higher névé that becomes the _surface-ice_ of the glacier near its end. The waste of the surface below the snow-line brings the deeper portions of the ice more and more to the light of day.