Glaciers in general, like rivers, alternate between distinct falls and more level slopes of smooth shoot or broken rapid. The routes through the smooth sections are easy to trace out from above, more difficult from below. The falls are more difficult to unravel from above, on a descent. In coming down large dry glaciers we can assume that a fall rarely extends equally broken right across the glacier; and that there will be a long bending eddy of smoother surface dallying close round the edge of the more broken section, which may afford us a passage through or round the rapids. On a small or steep glacier, where the fall visibly occupies the whole breadth of the glacier, and there is no eddy round it, it is useful first to discover if there may not be a direct central line which appears to force through the fall a long arrow-point of lazier, more level flow, such as we look for when we are canoeing down rapids. Failing either of these, on a small steep glacier the fall is often best skirted on the concave, or on the shadowed side of the glacier. Only in rare years, of hot seasons following mild winters, do alpine crevasses, or more often one great crevasse, sometimes extend right across a narrow steep glacier, and offer no through route, or bridge. As a last resort then it may be necessary to take to the rocks at the side of the glacier and circumvent the fall.
To get off a glacier at the right point in the evening, and also to lose no time and patience when we turn down on to the big glaciers in the early morning, it is our business to have noted beforehand from above the lie of the crevasses, and the points where it will be best to start crossing their trend. Many glaciers tempt us with long sloping lines of good going where their crevasses slant inward and upward from the margin. If we follow these without pre-examination, we either find our entry carried out and across to where the systems meet and produce difficult ice, or our exit balked of a landing-place. A few resolute traverses of the side crevasses, based upon observation, will often take us on to the master-diagonal, that launches us clear of the central fall or lands us on our chosen marge.
It will be seen that it is of value to train the eye to read a glacier from above, and mark out the best route, before we descend upon it. This inspection should be made not only of the glacier on to which immediate descent is intended, but of all the glaciers commanded by the ridges upon which we are climbing in a given season. The information may be invaluable for a future day, and the practice will serve conveniently to develop glacier prescience and glacier instinct. In addition, we secure a general idea of the condition of the glaciers in a particular season, or in a particular locality, which will assist by analogy to the unravelling of other glaciers which we may have been unable to prospect. A good iceman not only notes from afar, but retains his recollection of the route he noted when he is actually on the glacier and exposed to the constant temptation of following lines of deceptive least resistance. A number of mountaineers learn to observe, but few to remember; and fewer still will uphold memory against the evidence of the moment.
Conversely, it is valuable practical training to note, when we are on a glacier, the character of its rock walls, and the points at which the ice could be reached on a descent of the last rocks from the surrounding peaks. The rock wall just above a glacier is like a sea cliff, smoothed below, and presents a perpetual problem, of ascent or descent. Long returns may often be avoided by our recollection of inspections of a particular wall, or by deductions from our memory of the fashion of rock finishes found on the local glaciers.
Glaciers vary from year to year, and change slightly from week to week, and even on familiar ground it is wise to keep ourselves up to date by using all points of observation for the rediscovery of their annual or local variations.
With a few general principles as guide, the instinct that comes with experience as our aid, and backed by the usual allowance of climbers’ luck, there may be said to be scarcely a glacier, in the Alps at least, which cannot be traversed by patience and skill in all but exceptional seasons. An additional measure of precaution must of course be conceded, if we are following a line after noon or after sunshine which we could take on trust in the frozen hours before sunrise. And even before sunrise, in negotiating steep glaciers, dry or snow-covered, a very careful eye has to be kept upon the chance of ice avalanches or of the fall of a sérac. For this risk is not confined to the afternoon hours, when they are most likely to fall. A warm night, or frost, tepid wind or rain, will put the last touch to the career of many vagabond pinnacles depraved by the sun of previous days.
Where we can command the distant glacier above us, it is not difficult to mark the dangerous pinnacles and séracs, and to calculate their direction of fall should they choose for it our moment of passage. Otherwise, if we are launched in the morning, without prospect, into the blind intricacies of a big ice fall, the traces of previous falls must be our signals. They will be either scars, from which we draw conclusions according to their appearance of age or newness, or, more frequently, the remains themselves of a past fall, shattered fragments of ice. From the surface of the blocks we know whether the fall was recent or not. If the surface is blue and new in the morning, it has been a recent or night fall, and another may be expected; the same if it has only the rime of frost upon it. If the surface has melted at all and been refrozen since the fall, it is the fall of the day before or of still older date, and it need not be especially regarded in making an early morning traverse. The differences are notable, and a practised eye, backed by knowledge of the weather immediately preceding, can say within a day or a night when the fall took place, and whether it was a day or a night fall, and judge accordingly, with some probability of correctness, when a similar fall may be expected. Again, if there are traces of several falls of different dates, the passage is exposed to the raking of more than one periodic sérac mass, and it must be avoided. If it is but a single old fall, of a complete sérac, which no expert will have difficulty in discovering, it cannot fall again and may be disregarded.
After the sun has once risen, all commanding and large séracs, even if there is no trace of previous falls, must become objects of suspicion, if we have to pass below them. Their period of decline and fall is proceeding, and its close cannot be calculated nearer than within a few hours.
But a skilled party, with claws and experience, need not be afraid of adventuring on to a crossing of the wettest, bluest, and nastiest-looking séracs, provided that they can work out a route of safe footing and that the threatened zones are visible, and therefore avoidable. So long as snow does not conceal the cleavages or muffle the frailties, the difficulties of ice, as such, are a delight to master. With a good axe, good claws and a good friend, to set one’s feet on the crisp spring of morning ice and feel battle joined with the white, blue and silver giants of a glacier fall, I know no excitement so sanely joyous; and no sound so thrilling as the clean hollow smack of the axe and the bell-like rustle of the falling ice-chips returning from the deep crevasse; and yet again, no exultation more healthy than to look back through the glittering labyrinth of turquoise and grey precipice, of sapphire chasm, fretted spire, and lucent arch, flake and buttress, and see the little serpent of our blurred blue steps, edged with the tiny winking prisms of sunlit ice-dust, soaring, dipping, circling, hazarding on its absurd adventure: surely a connected thread of very happy human purpose, asserting its gay consequence triumphantly through the heart of the wildest and most beautiful of the conflicts between nature’s silent armies.
Snow-covered Glacier.