In the spring of 1866, the late Principal J. D. Forbes urged me to endeavour to find out more about the “veined structure” of glaciers, which he then, and, I believe, until his death, considered, was very much in want of elucidation. After thinking the subject over, it seemed to me that its difficulties were so considerable that it would be useless to attempt to grapple with them except in a thorough manner, and that it would be necessary to scrutinise and to follow out the gradual transition of snow into glacier-ice, from beginning to end, in at least one glacier. Superficial examination was almost worthless, for it was known that the veined structure, or structures, existed in glacier-ice above the snow-line; and hence it appeared that the only effectual procedure would be to sink a number of pits or trenches through the superincumbent snow, commencing at the very birthplace of the glacier, and to watch its growth and structural development as it descended to the lower regions. This opinion I still entertain.

I left England at the end of July, with the intention of sinking several pits in the Stock Glacier, which descends towards the northeast from the Col de Valpelline.433 In the first instance it was desirable that a trench should be made in some position that was free from local interference, and in this respect the Col de Valpelline was an excellent station. It was a snowy plateau⁠—almost a plain (without any protruding ridges or rocks)⁠—which gave birth to two great glaciers⁠—one (the Stock Glacier) descending gently towards the northeast, the second (the Valpelline Glacier) falling away rather more rapidly to the southwest.434 Wretched weather and other troubles retarded the work, and only one pit was sunk in the time at my disposal. This was a little more than 22 feet in depth; and, although it threw scarcely any light upon the veined structure, it yielded some information respecting stratification of snow and the formation of glacier-ice. I will describe, first of all, how the work was done; and secondly, what we observed.

I arrived at Zermatt on the 30th of July, possessed of a pickaxe (one end of the head pointed and the other adze-shaped) and a couple of shovels; engaged three common peasants as labourers, and Franz Biener as guide, and waited some days for the weather to improve. On the afternoon of August 2 we started, and camped on the rocks of the Stockje,435 at a height of about 9,000 feet. It was a very gusty night, and snow fell heavily. Great avalanches poured down frequently from the surrounding slopes into the basin of the Tiefenmatten Glacier, and minor ones from the slopes of our tent. We left our camp at 9:20 a.m. on the 3rd, and proceeded to the summit of the Col (11,650) against a bitterly cold wind, and with the clouds embracing everything. I marked out a place for excavation, immediately at the summit of the pass,436 24 feet long by 5 wide, and the men soon threw out enough snow to protect themselves from the wind. Two walls of the pit were dressed smooth, a third was left rough, and the fourth was occupied by an inclined plane that led from the surface to the workers. Two men were always at work; one hewing with the pick, and the other throwing out with the shovel. The others rested, and relieved the workers about every fifteen minutes. For seven or eight feet down they got along rapidly, as the stuff could be thrown out; but after a time the progress became much slower, for the snow had to be carried out in baskets.

After five hours’ exposure to the wind and drifting snow I was half frozen, and in a worse state than the men, who kept themselves alive by their work. All our faces were massed with icicles. At length I beat a retreat, and descended to the tent with Biener. The mists were so dense that we dared not use either veils or spectacles, and I remained snow-blind in consequence for two days afterwards. On the morning of the 4th my eyelids refused to open, and the light was painful even when they were closed. The men started off at 6:45, leaving me with my head tied up in a handkerchief, unable to eat or even to smoke! Biener came back at 4:30 p.m. and reported that the snow seemed to be getting softer rather than harder the farther they descended. On the 5th (Sunday) my condition was slightly improved, and on Monday morning I was able to make a start, and ascended to the Col to see what the labourers had done in my absence. They did not appear to have overworked themselves; for while on the first day they had got down more than 9 feet in 5 hours, they had, during the time I had been away, only accomplished 4 feet more. They accounted for this by saying that on Sunday night three feet of snow had drifted into the pit, and almost as much on Friday night. This, of course, had considerably added to the work. They were extremely anxious to get away; which was not surprising, as the wind was blowing ferociously from the northwest, and was tearing away sheets of snow from the summit of the pass. Indeed, it was impossible to stand against it, and in a single hour we should have been all frozen if we had remained upon the surface. I told them that they had only to reach glacier, and the work would be over at that spot. This consoled them, and they promised to work hard during our absence.

Biener and I then crossed the Valpelline and passed the night of the 6th at Prerayen. Upon the 7th we went down the Valpelline to Biona upon other business. On the 8th we returned to the summit of the Col, and found all three men sitting on the nearest rocks smoking their pipes. They admitted that they had done nothing on that day, but excused themselves by saying that they had got down to glacier. I found that they had only gone down another foot during our thirty-six hours’ absence. My wrath, however, was somewhat appeased when I went down into the pit. They had struck a layer of ice of much greater thickness than any which had been previously met with. It extended all round the floor of the pit to a depth of 6¼ inches. The men went to work again, and soon reached another stratum of ice of considerable thickness; or, rather, three layers which were barely separated from each other. After this, the snow seemed to be no denser than it was above the great layer. I waited some time; but my eyes were still very weak, and could not be exposed for many minutes together, so at length Biener and I went down to Zermatt through a terrific thunderstorm and very heavy rain.

On the 9th we returned again to the Col, and whilst climbing the rocks of the Stockje, discovered the dead chamois which was mentioned in Chapter VI. It rained as far as our camp, and thenceforward we had to fight our way up through continuously-falling snow, against an easterly gale. It blew dead in our teeth, and our progress was painfully slow. The snow was writhing all around, as if tormented; or caught by whirlwinds, and sent eddying high aloft; or seized by gusts and borne onwards in clouds which seemed to be driven right through us. The wind was appalling; once I was fairly blown down, although tied to Biener, and many times we were sent staggering back for ten or a dozen paces against our will. Our track was obliterated at the summit, and we could not find the pit. We tried east, west, north, and south, to no purpose. At last we heard a shout! We halted, panting for breath. Another! It came with the wind, and we had to face the storm again. After a long search we arrived at the pit, which by this time was a huge hole twenty feet deep. The inclined plane had had to be abandoned, and a regular staircase led down to the bottom. The men had again struck work, having, they said, arrived at glacier; the fact was, they were completely cowed by the weather, and had taken to shouting, expecting that we should be lost. I descended into the pit, and with two strokes of the pick went through their glacier, which was only another thick stratum of ice.

The last day had arrived, and the next was to see me en route for London. I drove the men to their work, and stood over them once more. The stuff which came up in the baskets was different from that which I had seen last! It was not ice of a compact kind like the horizontal layers, still it was not snow. Sometimes one could say, This is snow; but at others no one would have said that it was snow. On inquiry, they said that it had been like this for several feet. I went down, took the tools in my own hands, and hewed the walls smooth. It was then apparent that vertical glacification (if I may be permitted to use such an expression) had commenced (see A A on section).437

The men were anxious to leave, for the weather was terrible. The wind howled over our heads in a true hurricane. I was unwilling to go until it was absolutely necessary. At length they refused to work any longer; I concluded the measurements; we tied in line, and floundered downwards, and at 9 p.m. arrived at Zermatt.

I will now proceed to describe what we saw. For 11 inches from the surface the snow was soft and white, or what is usually termed new snow. There was then a very decided increase in density, and all the snow beneath had a slight bluish tint.438 At 21 inches from the surface the tone of the snow seemed somewhat deeper than that which was above, but below this point there was little or no increase in colour until the depth of 15 feet was passed. The density of the snow naturally increased as we descended, although much less rapidly than I expected. Down to the depth of 13½ feet (or to just above the broad blue band on the right-hand column of the section) the mass was decidedly and unmistakably snowy; that is to say, lumps could readily be compressed between the hands. This was also the case in some places below the depth of 15 feet. For example, at B B, on the section, the snow was not perceptibly denser than it was six or eight feet higher up. In other places, A A, it could not be termed snowy; it could not be readily compressed in the hands; and it looked and felt like an imperfect or wet and spongy form of ice. The colour at B B was perceptibly lighter than at A A, but it should be said that the colour here, and of the horizontal strata of ice, has been intentionally exaggerated upon the section for the sake of clearness.

The entire mass was pervaded with horizontal strata of pure ice. In the 22 feet that we penetrated there were 75 such layers, varying from one-tenth of an inch in thickness to 6¼ inches, which amounted in the aggregate to 25⅝ inches of solid ice. These strata were approximately parallel to the surface of the snow, and to each other. Not perfectly so; sometimes they approached, and sometimes receded from each other. Neither was their substance (thickness) constant. In some places they were more, and in others less thick. For example, the stratum which is between the brackets marked 1863⁠–⁠4? and 1864⁠–⁠5? was in some places an inch and a half thick, but in others scarcely an eighth of an inch. Upon the whole, the stouter strata were continued completely round the sides of the pit, and were tolerably uniform in thickness. The finer strata, on the other hand, frequently died out in short distances, and seldom or never could be traced completely round the walls. The finer strata also were much more numerous towards the surface than towards the bottom of the pit, and they were readily obscured by the drifting snow. It was obvious, yet important to observe, that the strata or layers of pure ice became fewer in number as one descended, and that upon the whole they became thicker.

I attempted to gain an idea of the temperature of the snow at different depths, but I do not care to quote my readings, as they were almost certainly falsified by the wind. I am not sure, moreover, that it is possible under any circumstances to obtain correct readings of snow temperature in the way that they were taken. The recorded temperatures, anyhow, must have been influenced by the surrounding air. If they were correct they proved that the lower strata were warmer than the upper ones.

We must now quit the region of facts, and descend to that of surmises and conjectures. The differences in the quality and in the tone of the snow of the first three feet below the surface were sufficiently marked to suggest that we saw in them snow belonging to three different years. The unanimous opinion of the four men was, that the uppermost 11 inches belonged to 1865⁠–⁠6, the next 10 inches to 1864⁠–⁠5, and the next 16 inches to 1863⁠–⁠4. In this matter they were not, perhaps, altogether incompetent judges. I am doubtful, however, whether their opinion was correct, and incline to the idea that the uppermost 11 inches had fallen during the summer of 1866, and that the succeeding 10 inches may have been all that remained of the preceding winter’s snow. Whatever surprise may be felt at so small a depth being considered as representing a year’s fall, must be modified when it is remembered that the position at which the pit was sunk could scarcely have been more exposed. We had evidence while we were upon the summit that a mere fraction only of the snow that fell remained in situ⁠—the wind tore it away in sheets and streams. It will be remembered, too, that no inconsiderable amount passes off by evaporation. If other pits had been sunk to the north and to the south of the pass, we should probably have found in them a greater depth of snow between each of the horizontal layers of pure ice. This is mere conjecture, and it may be taken for what it is worth. It is more important to note⁠—1. (a) That the fine layers or strata of pure ice were numerous towards the surface; (b) disappeared as we descended; (c) and that the lower strata were, upon the whole, much thicker than those towards the surface. 2. That the thickness of these strata of pure ice amounted to nearly one-tenth of the mass that we were able to penetrate. 3. That, below the depth of 15 feet, vertical glacification began to show itself. Upon each of these subjects I will now venture to offer a few remarks.

1. 1. The fine horizontal layers or strata of pure ice were numerous towards the surface. All of these layers had been formed by weathering at the surface. It is usual, even during the winter, for considerable periods of fine weather to succeed heavy snowfalls; and in these periods the surface of the snow is alternately melted and refrozen, and, at length, is glazed with a crust or film of pure ice. This, when covered up by another snowfall, and exposed as in the section, appears as a bluish horizontal line drawn through the whiter mass. The snow between any two of these layers (near the surface) did not therefore represent a year’s snow, but it was the remnant, and only the remnant, of a considerable fall, between whose deposition, and that of the next stratum above, a considerable interval of time had probably elapsed.

   2. The fine strata disappeared as we descended. I imagine that this was a result of pressure from the superincumbent mass, but I leave to others to show the exact manner in which these finer strata were got rid of. Is it possible to liquefy by steady pressure a plate of ice (say, one-tenth of an inch in thickness) placed in the interior of a mass of snow, without liquefaction of the snow?

   3. The lower strata of pure ice were, upon the whole, thicker than those towards the surface. This, doubtless, was a result of vertical pressure. The ice-strata thickened under pressure. But why should some grow and others disappear? I presume that the finest ones disappear, and that the stouter ones grow. Can it be shown experimentally that it is possible to liquefy by steady pressure a fine plate of ice placed in the interior of a mass of snow, and at the same time, under the same conditions, to thicken another and stouter plate of ice?

2. These horizontal strata of pure ice amounted in the aggregate to nearly one-tenth of the thickness of the mass that we penetrated. It was perfectly well known prior to 1866 that the upper snows (which give birth to glaciers) were pervaded with strata of pure ice, and a number of observers had written before that date upon stratification of snow and of glacier. It may be questioned, however, whether any had an idea of the very important amount of glacification that is effected by superficial weathering, and subsequent thickening of the strata through vertical pressure. A search through the works of the principal writers on glaciers has failed to show me that any person imagined that one-tenth of the mass, or anything like that amount, may be composed of strata of pure ice.

   There are two points in regard to these horizontal strata of pure ice that are worthy of consideration:⁠—(a) Does not their existence, and especially the existence of the fine layers towards the surface, conclusively disprove the idea that the production of glacier-ice is greatly promoted by infiltration of water from the surface? (b) Can these numerous strata of pure ice (some of which are of such considerable thickness, and extending over large areas) be obliterated in the subsequent progress of the glacier? If so, how are they obliterated? Or is it not reasonable to suppose that these thick strata of solid ice must continue to exist, must continue to thicken under pressure, and must supply many of those plates of pure ice which are seen in the imperfect ice of the glacier, and which have been referred to at different times and by various persons as the “veined structure?”

3. Below the depth of 15 feet the appearances which I have ventured to term vertical glacification were first noticed. Were they accidental? or will they be found at or about the same depth in all other places? Into what would those appearances have developed at a greater depth? What produced them? These questions may perhaps be answered one day by future investigators. I cannot answer them except by guesses or conjectures. Most unwillingly I left the excavation just at the time when it promised to yield more valuable information than it had done previously; and since then I have never been able to resume the work. I believe that the exposure of considerable sections of the interior of a glacier, at different parts of its course, would yield information of extreme interest; and that more light would be thrown in such way upon the doubts and difficulties which attend the formation of glacier-ice and the “veined structure,” than will ever be thrown upon those vexed subjects by wandering upon the surface of glaciers and by peering into crevasses.