VIII. RECONNOITRING
Reconnoitring precedes in action the exercise of mountain craft. But as an art it is the gold cup in the sack mouth of a mountaineer’s equipment. Its effective mastery must rest upon his previous accumulations of practical experience. It may therefore, fittingly, be put in last.
In the Alps and nearer European ranges, maps and guide-books relieve the mountaineer of almost all occasion to apply his powers of observation to the interpretation of the Seen or the reconstruction of the Unseen. The majority of men who climb in the Alps or Britain get no practice in making even elementary deductions from scenic details within sight; and a number more, whose experience and observation have been sufficient to enrich them with what they would call an instinctive feeling about the meaning of topographical details which they can see, or about the probabilities of those which are out of their sight, have never, for lack of opportunity, been forced to resolve this feeling into precise conclusions.
Nothing but actual necessity, the need of providing for safe progress or comfort, will induce most men on a holiday to exercise or educate their observation. The loss is considerable; not only because a developed faculty of observing, and of reasoning from the observations, is in itself a valuable permanent possession, but because the neglect involves the failure to see much that is beautiful. If we are accustomed to wait until beauty imposes itself upon the eye, as in the end it will, and almost flauntingly, in large mountain scenery, we shall have already missed the discovery of the relations of line and colour and mass to which the beautiful effect is due, and we are fated to overlook much that is lovely and much that is interesting in regions where there is grace and interest in the smallest detail, but where detail escapes unperceived among the broad and salient features of familiar magnificence.
[Illustration: MOUNTAIN ARCHITECTURE [C. F. MEADE]
On a more material plane, a man who aspires to lead a party must be able to ‘see,’ in the sense in which an artist or natural scientist ‘sees,’ and he must be able to make the necessary mountaineering deductions from his sights. A mountaineer who wishes to conduct an expedition efficiently in unexplored ranges must be able to do more: he must be practised in the art of confirming conjecture as to what is beyond his sight from ‘signs’ within view. For an expert of this sort it is fortunately sufficient to indicate what he can discover and how to set about it; fortunately, because ‘signs’ in practice are so modified by place, climate and season that no rules could be laid down without a page of exceptions to prove each one. One day of practical demonstration under guidance will reveal more of what we ought to see and how to see it than much tabulation. We may write of a ‘snow sky’ and an ‘ice sky,’ and a mountaineer who had them pointed out to him would recognize the difference; but we cannot with truth say “a snow sky is a whitish-blue, or shows as a white underside on a cloud,” or “an ice sky is a greyish-blue, and reflects in a shade of grey from a cloud,” because a different climate or region might anywhere contradict our colour definitions. But the distinction between the two would remain as a constant difference of tone under all identical conditions, and it would be perceptible to a trained eye.
Somewhat the same difficulty interferes with any accurate summary of more elementary signs to be looked for in reconnoitring,--signs whose discovery is, or should be, part of our daily alpine routine. Every mountaineer should know at a glance, in the right conditions of light, new snow from old snow, ice from crusted snow surface, open glacier from firn or névé. But who could learn to recognize the differences, under continually changing conditions of light, from his recollections of a written classification? The suggestions here made must be understood, therefore, only to affirm that between certain groups of surface appearances there are certain constant relative differences, whose presence, or absence, can always be ascertained in the right weather and light. They are intended to indicate a few lines of less obvious investigation, which the trained eye can pursue in examining aspects and details of mountains that are visible to everybody but not equally intelligible to everybody; and further, to outline a province of yet more difficult discovery--the collection of information as to aspects and details which are not even in sight.
It may now be assumed that until a mountaineer knows something of his craft by actual experience, the choice of a route up a peak need not be left to his unaided attempts at reconnoitring. Elementary mountaineering information is far more widely diffused, and practical climbing ability has become almost an inherited instinct. The method adopted by the Badminton on Mountaineering, and by various excellent manuals in imitation of it, first synthesized for us a sample peak or climb, resolved the attributed features into their simple elements again, and then directed us, with natural confidence, precisely how to deal with them. A method advisable for purposes of picturesque propaganda in earlier, darker days is of less service to a climbing generation whose acquired craft can be more generally trusted to know how to attack its peak, if it can once attain to only a small part of the certainty about the real character and the momentary condition of distant detail which these illuminating studies could happily assume. The path so well prepared by our predecessors for the straying or reluctant feet of the potential climber, and so entertainingly bordered with composite examples, need not be retrodden. Guidance in reconnoitring, to be of later use, must now wait for its opportunity further along the way, and be ready to pester the progressive competence and self-assurance of zealous mountaineers with the well-meaning but aggravating importunity of an elder walking companion: “Can’t you see that?” and, “What does it mean?” and, finally, “Well, then, I’ll tell you!”
Snow and rock and ice, as a triune element, alone concern us. What we need to find out about them is their respective angles, to know if we can get up at all; their several conditions, to ascertain if we can do so with or without danger or difficulty; and the degree of modification which their combination may be introducing, in order to decide if we can do so within the appointed time. For instance, our agreeable opinion of the angle of a rock rib will counterbalance our unfavourable view of the state of a snow face, which it relieves; or our optimistic impression of the snow in a couloir will free us from the gloom created by our sight of the angle and character of a rock wall, which it bisects. With a peak as such we are only concerned in so far as it presents to us a greater or lesser mass of favourable or unfavourable angles and superficial conditions. We take it that our climbing craft can get us up any mountain by any way visible or invisible. It is for our reconnoitring craft, first, to reject those alternatives which are interrupted by the angle of the impossible; secondly, to condemn the lines where it detects surface conditions or direct menaces which will introduce too large an element of danger; thirdly, to except the routes where it decides that harsh angle and poor condition in unrelenting succession combine to form too great a volume of difficulty to be humanly vincible in a single expedition; and lastly, if no agreeable or interesting remainder be left over, to use its utmost skill to determine whether some unseen aspect may not reveal sufficient of its character to encourage a hope that it will offer a more helpful line of attack.
The sum of the results of these investigations will of course add up differently with every peak, and any discussion of it in the abstract could only be hypothetical. The decision as to whether this sum in any concrete case represents a feasible or justifiable mountaineering attempt must take into further account the strength of the party proposing to make it, and must be therefore, for us, equally hypothetical. All that the grammar of reconnoitring can usefully define are the lines which investigation should follow in order to secure exact information about the elements which are the material for our calculations, and therefore the chief factors in our decisions. Snow, rock and ice are these elements; and their state, angle and influence upon each other in certain combinations form the only matter that need concern our examination on the spot,--or here.
THINGS SEEN
To discover whether a distant slope is snow or ice, if the character of the surface is not apparent at once, or deducible from its position, aspect or angle, we must wait for sun or strong daylight.
[Sidenote: Snow Surface Condition.]
Ice surfaces--that is, the smooth ice surfaces found in the Alps--reflect light as an even, steely glimmer, like elongated pools of water. Black ice, not so often found in the Alps, has a different quality in reflection. Granular ice is distinguishable by its reflection of light in facets or prisms. It will be noted that these tend to increase in size as our inspection descends the length of a glacial slope. The honeycombed ice found in tropical ranges is quite distinct in character; it can be recognized from a distance, and in a photograph, by its surface forms.
Snow surfaces show plain white or grey in comparison.
An ice crust upon snow has an appearance much like that of ice, but the reflected light is ‘pockled’ and uneven.
New snow, which is best left alone, has a brilliant fresh surface. Seen even from great distances, and especially upon rock, it shows a filmy, gossamer, veil-like quality. This endures until the aeration has escaped and the feathery surfaces have subsided into harder contours.
Old powdery snow, as contrasted with new snow, has a greyer tint when seen from a distance, particularly if not seen in direct sunlight.
Old wet snow, laborious to cross, and deciduous according to its angle, shows a bluish, luminous surface light, especially in its depressions. It is often transected by visible lines of strain or cleavage.
A thawing snow surface, seen from near, is dull and drenched looking, or pitted with small holes.
Surface hard-crusts, or plates, produced alike by wind and sun, which afford pleasant going but possess the avalanche potentiality if the angle is steep and their attachment to the surface below is slight, generally mark themselves off from the surrounding snow slopes by a lower, duller tone; sometimes they are tinged with a yellow shade. The plates vary in thickness, deepening towards the middle, and they can often be recognized by their edges, which run out on the neighbouring snow in darker wavelets, sometimes with eyebrow-markings round their curves.
Old hard snow, of deep attachment and sound progress, lies in alternating wave and hollow of different tones of light and shade, where the sun has been at work on the surface. It is often dust-speckled, or shows bluish finger-prints.
Granulated snow, in strong light, may show bright or prismatic reflections from its facets, similar to, but easily distinguishable from, granular ice prisms.
As confirmation, or correction, of what distant observation may have revealed about the character of ice or snow surfaces, general considerations must also be taken into account: the recency of the snowfall, the subsequent weather, etc. There is also the final test of touch, which is made on the spot, before any snow slope is traversed. The change in the condition of the snow, which may be produced by a day of sun before we can return down the slope, must not be left out of the calculation. Many slopes whose surface may be adjudged and found safe for passage in the early morning cannot be trusted by nightfall.
[Sidenote: Angle on Snow.]
It is essential to be able to judge of the inclination of a slope; for some harmless conditions may become dangerous if the snow is lying at above a certain angle. New snow, for instance, has been known to slide at as low an angle as twenty degrees. Hard old snow, melted and refrozen, may be supported in small patches, and remain reliable, at as high an angle as sixty degrees.
The power to estimate the angle of a slope by the eye only comes with practice. Most slopes look precipitous in face. But a mountaineer who has trained his eye by first going round to see a number of such slopes in profile, and by then returning to see them in face, has learned what he must deduct from an apparent angle. He is then qualified to make a truer estimate of the real angle of slopes which he may be able to examine in face alone.
Snow cannot lie at anything like the angle at which it often appears to lie when seen in face. From the presence of snow, in fact, much can be argued as to the generally mild angle of the mountain face on which it lies. Except in narrow couloirs, where it is supported by the walls, snow does not lie permanently above or even up to an angle of fifty degrees. Most big snow slopes are considerably less. The broader the face on which it lies, usually the less the real angle of the snow.
The fact that a big snow peak presents a continuous slope of snow to its summit is evidence that the mean angle of the ascent is not great, otherwise the even accumulation could not have proceeded. In prospecting a new mountain, therefore, however tempting its rock face or ridge may be to a modern climber, its snow side, if it has one, may be assumed to offer the inclination of easier ascent. And this more particularly if the snow slopes face towards the south, where the snow would naturally adhere least to the face.
Interruptions to climbing on such snow faces, whether as steeper slopes of snow or as ice walls (such as it is well to note beforehand), are at once apparent from their different shading if the snow slopes are inspected when the sun is overhead.
The inclination of a hanging slope of snow always appears still more exaggerated as seen from in front if it lies on the face of what is mainly a rock peak. We have in such case to discover if the snow is lying on ice, or only forms a coating to the rock. If it is on ice, the lower edge of the slopes, where the snow runs out on to the rock, will generally betray a rim or broken wall of ice. To judge of the quality of such a snow surface, and of the strength of its attachment to its ice or rock sub-surface, the slopes below it must be examined, and snow, stone or water furrows looked for. By the crumpled or the clean appearance of the edges of the slope itself, where it touches the rock walls on either side of its descending fan, much can be learned of its past transmutations and present condition.
Long or short spits of lighter snow, running up against darker snow or ice, are the retentions of later falls, and are indications of uneven angles of surface. They betray the presence of bulges or ribs below, and, besides their promise of easier progress on slopes where the general surface may be frozen hard or over-steep, they give us by their contrast a further basis for our estimate of the actual inclination.
The presence, the shape, and the number of cleavages or crevasses in a slope of ice or snow are a further guide to our estimate. A certain type of crevasse is only found on slopes lying at an angle of about forty-five degrees.
We may get additional evidence, in cases of doubt, by waiting for the sun to throw the shadow of another peak or shoulder upon the slope. When the sun and the interruption are located, the distortion of the reflection will allow of an approximate estimate of the angle of the snow slope.
Faces or ridges of mingled rock and snow, and surfaces interrupted by the intrusion of any detail, be it only of a shadow or tint, are always easier for the experienced eye to estimate, in angle and character. Where we have rock and snow or light and shadow in contrast, practice in the reading of snow and ice surfaces, and in the rules that govern their angles of inclination and attachment, and practice in the interpretation of the details of rock structure, become mutually and comfortably corrective.
[Sidenote: Snow Cornices.]
Cornices form against the wind, not with it. The contrary is sometimes stated; but the error is possibly due to the fact that irregularities in the configuration of a ridge often produce back eddies in a cross-wind. If the prevailing wind is snow-bearing, and across, a snow-bearing back swirl may build a small cornice on the sheltered side of a ridge. Such a small cornice would appear to have been formed with the prevailing wind: actually it would have grown against its return eddy. A wind blowing along (not across) a serrated ridge may similarly produce very small cornices facing either way on the ridge, and apparently at right angles to the prevailing current, owing to some tower or curve on one side or the other having created an inward and upward cross-eddy, and a shelter from the main-current in which the snow-laden eddy can work. Large cornices facing either way on the same ridge, and the double cornices, are produced by a shift in a snow-bearing cross-wind to the directly opposite quarter. If we find ourselves on a corniced ridge when a strong wind, and especially a strong wind from a warm quarter or with Föhn in it, is blowing against the back of big cornices, i.e. from the opposite direction to that from which the snow-bearing wind was blowing which formed the cornices, we have to be even more careful, if that be possible, in dealing with them, as such a wind will loosen their attachment and magnify the suddenness and the size of their collapse. A cornice will always form more easily on the summit of a sheer or abrupt wall, which creates a strong upward eddy in a wind blowing against it, than upon a more gradual or snow-rounded inclination which offers less resistance to the current and less ‘catch’ to its snow burden. For this reason, upon a summit or a ridge which has, as so often is the case, one more gradual snow side and one rock side inevitably steeper, we must be prepared to find cornices overhanging the rock face, larger if produced by a wind-shift, lesser if by a back eddy, even though the prevailing wind has blown regularly upon the opposite snowy face, and should have relieved us of the necessity of caution by its failure to develop cornices on that side.
In general, therefore, the direction of the prevailing wind can give us no certain guidance as to whether or not to expect the existence of cornices. If a snow-bearing wind has blown against the visible side of our ridge or summit, we shall see them. If upon the invisible side, we must assume their presence until we can disprove it. But a wind-shift or variable current may always contradict our calculations. A cornice is very quickly built.
If we have not been following the performances of the prevailing wind, or if we mistrust its portent in any case, we have to rely upon visual evidences when we are prospecting the approach to any snow summit or the traverse of any snow-crowned ridge. In the case of a single summit it is less trouble to assume the presence of a cornice, until we fail to find it. In the case of a continuous ridge it may save us much tribulation to ascertain its condition in this respect before we start out for a long day upon it. If there are cornices, and they project towards us, they will at once be recognizable; if away, it is not always easy to make certain, without getting a sight of some part of the ridge in profile. Their detection at one point of a ridge will dictate the necessity of precaution along the rest. A telescopic examination can often discover the thin dark line of junction or strain, running parallel to the crest in the snow on the near side, where the projection of a cornice towards the far side starts its inclination. (In more considerable snow ranges, such as the Andes, this crack has, I am told, on occasion been proved to be due to a longitudinal crevasse on the ridge. In the Alps, however, I know of no case of this having been observed.)
An alternative and rarer indication will be the discovery of a band of shadow or duller tint, seen in the right light, running along the snow wall just below some part of the crest. This will be due to a relative steepening of the snow wall, sometimes even taking the form of a concavity, where the back of a high, steep cornice, facing towards the far side, hummocks up off its supporting ridge. The appearance I believe to be occasioned by a fall or a shift in the prevailing wind,--a fall permitting the snow to accumulate upon the head of the cornice and form a sort of bulbous whale-back over it, or a shift of wind to the near side beginning a projection which may ultimately grow into a ‘double’ cornice, with the higher of the two facing towards us.
Failing either of these signs, any two projecting points of rock or snow, near together on the suspected ridge, should be examined. If the connecting line of snow between them shows sharp and continuous against the sky, and ascends at its either end in a continuous single curve to the points selected, the cornice on the far side, if any, will be slight and local. If, however, the snow rim seems to merge indefinitely on the skyline, and its curve ascends to the points at either end in a variable arc of different centres, so that we seem to see, as it were, round the edge of a fold where the snow-curve hangs to the rock points, a cornice is indicated. If the breadth of the points or towers is sufficiently ascertainable to enable us to estimate the average thickness of the connecting rock ridge hidden below the snow between them (as it usually is unless the towers are seen absolutely flat in face), then the look, almost a reflection, in the sky immediately above the snow curve, and the character of the snow curve where it wavers over against the sky, will indicate to an expert eye whether the cornice is large or small.
Where, again, sufficient rock points projecting from a snow ridge are visible, as we see it in face, to suggest what must be the actual line of the snow-covered rock connecting them, any wayward sweep away from us in the visible line of the snow between them is an indication that the snow rim, where the skyline thus unaccountably retreats from the eye, is superintending a cornice on the far side.
The presence of a double cornice--the fatal cornices that face two ways, one built up above the other--is not difficult to establish. A band of shadow or low light on the near side of a snow crest, below a band of higher light, means a lower cornice facing towards us under an upper cornice curving away. A band of markedly higher light, below a band of shadow or obvious concavity, means an upper cornice facing towards us above a lower cornice facing away.
For all such observations on snow, which find their opportunity in the relative positions of light and shadow, it is apparent that a time must be chosen when the sun shines from the right quarter. Their accuracy depends upon their being continued over a time sufficient for the sun to travel past, and so indicate to us dimension, by the change in, or the disappearance of, the shadows cast.
[Sidenote: Wind and Snow Signs.]
Wind is not ‘seen,’ but its immediate effects upon snow are, more especially on high ridges, corniced or otherwise. The quality and quantity of the surface snow on a ridge, which it is important to know beforehand, can be discovered in times of wind from the amount and direction of the snow particles, which are seen to be blowing off the ridge, and appear as a film or puff of vapour upon the sky just above. The absence of any halo to the ridge, in spite of the manifest action of wind upon adjacent clouds, is equally valuable evidence of the stable quality of the snow.
The direction and force of the wind will often suggest the side of the ridge to which we shall prefer to limit our passage on the morrow. On the windy side, if the ridge be snow-covered, according to the quarter and character of the wind, the snow will be crusted or hard, or we may have to encounter a bare sheet of ice. If it be rock, again according to the wind, we shall find the holds either cleared or ice glazed in the morning. On the side sheltered from the wind, on a high exposed ridge the snow should be just of good quality. But even on such ridges it may be spongy and cantankerous if the wind has had Föhn in it.
In a bad season, or after a storm of ‘dry’ snow, it is worth while examining high ridges that have been exposed to the wind, on the chance that they may not have been closed by snow for the usual three days, like other peaks. A friend and I owed our own last great climb to having observed that the Zmutt ridge of the Matterhorn had been blown black and bravely snow-clear by the same storm that sheeted all the other ridges and summits of Zermatt in white, untimely mourning.
Apart from the indirect evidences it brings, wind, keen or warm, gusty or continuous, has its direct bearing upon the comfort, the safety and even the possibility of our climbing. Of its effects on snow surface, on rock falls and upon morale I have written elsewhere.
[Sidenote: Ice.]
Ice sheets on snow peaks are located from a distance by their reflected light; but it is well to memorize or sketch their position and extent beforehand, especially if we expect to have to cross them upon our descent, since they will be usually invisible from above. If there is prospect of our glissading, the exact positions of interruptions, ice shields, bosses, etc., must be known in advance.
Ice upon rock is apparent, either as a grey-blue, bottle-glass bordering to the stippling and nestling of old snow, or in the refrozen festoons of new ice, exquisite and evil, that complete the Gothic character of granite pinnacles.
Lazy, main glaciers reveal themselves frankly. The solution of their complexity is the business of ice craft; but distant inspection is concerned to discover the easiest line of ascent or descent, if the glacier is to form part of the expedition.
The most difficult hanging glaciers--that is, those with the largest systems of crevasses--will be as a rule the most steeply inclined. They will be therefore the easiest to prospect, even in detail, as seen in face from far off. Very few hanging glaciers descend evenly or straight. Either side or the centre will be moving the faster, and receiving the fuller reinforcement. The line of the great crevasses will slant upward or across, from one side to the other, or from both sides to the centre. And along the edges where the lines of varying pace and pressure adjoin and descend in conflict will be found, if there are no abrupt ice falls due to uneven bedding, the least interrupted route. Contrary pressures often tend to squeeze up the ends of successive cross-lines of crevasses, creating a tortuous but consecutive eddy of passage. Though the crevasses may still exist, as walls, séracs, etc., they will be more compressed and negotiable on this line. Frequently the cleavages will here survive only as partial splits, and across and down the edges of the unsevered splinters or flakes a continuous descent will be possible. But climbers may skirt round the mazes of glacier causation, if they have but eyes for the visible surface clues. It is enough for them to note from afar and remember by marginal marks where the best line of traverse from side to side, or from side to centre, should be started, in order to keep or recover the mobile thoroughfare. On large glaciers this is often very difficult to rediscover once we are on the ice, when our view is restricted by its irregularities of surface.
Similarly, to enable us to get on or off any glacier, we should note beforehand the position of convenient side-bays, where the ice runs out on to the rock in smoother, spent waves.
[Sidenote: Couloirs.]
Even as the passage of couloirs might be considered as belonging to snow and ice craft or to rock craft, so also their consideration is transitional to rock reconnoitring.
On large mountains the important thing to know about a couloir beforehand, if we intend to use it, is whether it is filled with ice or with snow, and whether it is subject to stone fall.
To information on the first point, the study of the angle of the couloir is the first help. A steep angle generally implies that the lining will be ice and not snow.
But as snow, supported by retaining rock, may remain at a very high angle, we look to see if there are any furrows in the white surface. If there are furrows and they are in ice, they will show us ice reflections in sunlight. If there are no ice reflections and they are therefore in snow, or if they are only ice-backed and therefore in snow-covered ice, the depth of the furrows will tell us what depth of snow we may expect upon the ice. If there are no furrows, the edges of the supposed snow must be inspected for further information. Where the snow runs out on to the rock at the side in ice webs, the surface tone will appear of different qualities if it be snow on ice, or if it be ice throughout.
And after all our examination, we may be agreeably surprised to be able to ascend on hard snow in the early hours where we had calculated from the angle that we should be hacking in snow-ice; or as disagreeably disappointed to find snow of avalanche quality, on a late return or after warm wind, where we had located snow of the best bearing variety during a morning inspection.
The base of the couloir should be inspected for traces of previous snow avalanches, and for the character of its bergschrund. We see if we can whether the summit of the couloir is commanded by glacier or slope likely to use it for the discharge of snow or stones. If so, we note during what hours the presence of sun will increase the risk, and when shade to diminish it may be looked for.
In a big couloir we mark down islands of rock which, in case we are detained in the recesses until stone fall time, will provide us with screens below which to steer our line.
We study the lie of the strata and the containing walls for possible exits from the couloir. On big peaks the top of a couloir often opens upon an amphitheatre of slabs, too thinly ice coated for steps. It is then important to mark down a line for escape in time.
If the base of the couloir selected can be seen, the presence there of fallen stones is evidence that they have fallen; but their absence there is not conclusive that they have not. They may have been swallowed by the bergschrund, disappeared into some crevasse, or lodged in soft concealing snow. For this end we must examine the edges of the schrund and of any cleavages for traces, and the surface of the lower snow for pockling. If there are channels worn in the snow or ice at the base or back of the couloir, we shall get further evidence that something is accustomed to fall. These channels may have been made by stones, by ice trash or by water. In sunshine the difference is distinguishable. If the runnels are ‘silver-backed’ in sunlight, and there are no stones apparent, they have been made by water and are harmless.
If the couloir to be visited descends on to a visible glacier, but is itself invisible, the presence, absence or scarcity of fallen stones discoverable at the bottom end of the glacier, subject always to the possibility of the consumption by rift or crevasse, will demonstrate the couloir, or couloirs, commanding the visible glacier to be proportionately infected with, free from, or only in some cases liable to, the falling sickness.
[Sidenote: Rock.]
In prospecting rock routes we have more to help us; for rock, unlike snow, does not change its skin, and when it hides itself, under ice or snow or water or glaze, the change from the black Ethiopian is obvious and calculable. We have also preliminary information, if not in books yet in the outlines of the mountains themselves, as to what is the character of the particular rock before us. Every climber, if he can assume the presence of limestone or granite or dolomite, sandstone, trap, chalk, or a few other of the elementary and lay classifications, has a clear picture in his own mind of the kind of climbing and of rock holds that he may expect.
[Sidenote: Faces.]
The slopes of the hills will tell him in general; good glasses will tell him more of his particular route or of local modifications in the characteristics:--such as how the rock is weathering; in which direction the strata are dipping; and what is the fashion of the jointing. Putting this information and his knowledge of the type of rock together, he will know upon which side to attack his peak.
For instance, if the strata dip through the peak, the aspect of the mountain upon which the upper ends of the strata emerge will give him holds sloped upwards to his advantage. This side, with its retroussé ledges, will also hold fresh snow longest after a fall, and at such a time afford him a further chance of locating the lie of traverse and shelf. If the main cleavages, again, are vertical, he will select the most weathered face, where the jointing will give him platform and shelf. If they are in the main horizontal, he has to seek the side that presents the most sequent line of weathering rifts or fractures, in order to connect up the natural horizontal ledges.
Just as a sunny day is of most help in prospecting an unknown snow climb, so is the day after a snowfall invaluable for the examination of rock routes. I owe several fine new rock climbs to snowfalls. Not only does the lodging snow indicate particular ledges and their intervals in detail, but it discovers to the eye general connecting lines of traverse or slope, which may be too interrupted or too foreshortened to be perceptible upon a distant inspection of the bare and broken rock face. Under snow the main lines of rock structure leap into sight.
By a convenient law of rock formation, the little apes the great. Thus, if we can discover the general inclination of traverses across a face, however large in scale, broken or interrupted their lines may be, it is safe to assume that the small details which make up these lines, the ledges, etc., will be reproducing the same fashion of structure in little. Where there are big terraces, there will be small ledges copying their form and direction. If there are big visible gaps, giant slabs, or terraces interrupted and continuing at a higher level as a result of uneven upheaval, in the same or similar places, although too small to be visible, the climber has to look out for exposed passages on slabs, or he will have to search for cracks to connect up his interrupted ledges.
It is all but impossible to inspect a distant climb with sufficient minuteness to be absolutely certain that a fifteen-foot wall or a broken ledge may not stop all progress at some point. Very rarely we can say, “It is impossible;” occasionally we can say, “It will go for certain;” but generally we have to leave some portion to the ‘round the corner’ chance. In such case we can reason with advantage from the big to the small, interpreting the main features of a face or ridge into terms of detail suitable for our lesser needs, and justifying it by our experience of similar rock.
Fortunately, rocks generally prove us right. They seldom cheat us, by a petty exception, of the fruits of general conclusions which we have based upon observation of their principal tendencies. On the contrary, we are constantly helped by kindly accidents and flaws, where we might expect no mercy. The Grépon traverse is a delightful instance of unreasonable progress just made possible by a series of, apparently, gorgeous accidents. The flukes are so brilliant and so timely that the layman cheerfully assumes them to be a rule in attacking similar Aiguilles; and he is rarely disappointed. When the expected and the unexpected alike fail us, on such rock we can still count upon a kindly roughness of surface and upon homely methods of friction to join up connections which structure and luck would have, for once, denied to us.
In reconnoitring all rock faces, especially for new routes, we are alert about the matter of falling stones. On boldly sculptured faces the edges of the ribs will be the safest line. On faces of shallow relief or much interrupted modelling, we may assume that nothing but the angle or our fortune will secure us against cross-fire. We used to be told that we should avoid stones by selecting aspects where the up-lie of strata emerged in sky-ward and stone-catching ledges. But personally, I have been seldom so badly bombarded as upon the Zermatt face of the Matterhorn, where every schoolboy knows what happens to the strata. If the rock is known to be good rock, or if we can design a route which by reason of its angle or its salience on the face should be safe, we may chance a few exposed connecting links. But if the rock is notoriously bad, or the disconnections in the safe route look to be numerous, and this especially if they occur high up where the sun will have had long time to act before we reach them, we must not risk the attempt. Years ago our party turned back from completing the ascent of the Furggen ridge of the Matterhorn on the ground of risk from stone fall. Later it was climbed; and the story of the success might be read as a commentary on the mountaineering value of the virtue of renunciation.
[Sidenote: Ridges.]
The same reasoning from the big to the little helps us in prospecting ridge climbs. If the succeeding edges, towers and large interruptions on a great ridge show a disposition towards maintaining a steady family connection, each with its neighbour, in spite of their bold skyline accidentation--(I cannot put this more intelligibly, but any student of natural outline will know what is meant)--then there is every reason to hope that the ‘cuts-off’ between them will also prove more relenting than they look. In their smaller detail the same indulgences, of ledge and flake and fluke in favour of the climber, will manifest themselves.
A ridge seen end-on is very deceptive. If it rises steeply, it may appear to be a continuous incline, whereas it consists really of separated, ascending ‘steps.’ If a side view is not obtainable, the look of the walls falling on either side from the ridge crest must be our guide. The depth, extent and number of depressions indicated in these side walls, seen in profile, will tell us that there are couloirs below, and therefore probably syncopations in the seemingly continuous crest-line above.
The projection of bulges or articulated ribs on either side wall may, similarly, be identified as the edges or supporting buttresses of isolated towers, whose depth of separation from each other is concealed from us in the foreshortening of the ridge.
Towers on a ridge, seen in flat from one side, are equally misleading. They are more often the ends of short ridges which run crosswise to the line of the main ridge than the needles which they appear to the eye. An inspection of the general lie of the strata will often tell us whether we may assume this to be the case.
If we can get both an end-on view and some oblique view of the ridge, or of any tower upon it, we can reason fairly closely what the two unseen sides of any spire will be like, and even whether they can be expected to offer traverses conveniently sloping, or weathered surfaces, such as the dip of the strata and the jointing deny to us upon the visible sides.
Allowance must always be made for the deceptive outlines that are introduced by foreshortening. A view from some second point is often necessary to counteract their false impression.
In prospecting a ridge for purpose of traverse in the early morning, it is well also to note which side gets the sun soonest and keeps it longest. On this side we shall find the holds most clear of snow or morning glazing, and be able to escape the chill to the muscles of shadow on cold rock. The rock on this side also will, for the same reason, be probably the more superficially disintegrated, and so offer a greater choice of holds, though not necessarily holds of such good quality.
[Sidenote: Slabs.]
In reconnoitring slabs, on faces or on the side walls of ridges, we find that their apparent angle as seen in face is as misleading as that of snow slopes. In their case we have not the presumptive knowledge that they cannot be as steep as they seem, since rock may be as perpendicular as it looks. Nor have we the subtle variations in light and shadow which help us, on snow, to correct the eye. Rock faces are so broken that it is seldom possible to get the assistance of sun shadows in estimating the angle of portions of their surface.
On the other hand, acquaintance with the characteristics of the particular type of rock, and the visible general inclination of its strata, give us a groundwork for a preliminary estimate of its slabiferous sections.
New snow can again come to our assistance. Snow will reveal to us an easy angle by lying over our slabs as an even cloak; or it may display a vertical section by missing it altogether. It will also indicate the surface in some detail, by the fashion of its distribution on ledge or pocket.
Otherwise we must try to secure a side view of bare slabs, or at least a second, oblique view. If this is not to be managed, it is of use to inspect any near and more approachable slab of similar formation. By an examination of the profile of a ‘sample’ slab we are often able to revise our estimate of the angle and potential holds of its bigger, remoter neighbours.
But on rock the final judgment of doubtful passages must be left in the end to the practical test of attempt. The only infallible criterion is its tactile value. When we have reduced the ‘impossible’ sections of a route to a few isolated passages, it is always worth while going to see. The accidents of rock, its roughness, its whimsicality and its reticences are nearly always in the end in our favour. If we can only make sure that the rock is sound, and fix a general line of ascent, the overcoming of the ‘impossibles’ or the ‘improbables’ in detail can well be left to the moment. If we could map out a whole climb before we did it, much of the pleasure would be lost.
To the resources of rock technique no rock that is sound, and not obviously absurd, is impossible, either by attack or turning movement. And we may assume this to be so until we have ascertained by ‘rubbing our noses against it’ that we have lighted on the rare and unhappy exception.
[Sidenote: Rocks in Britain.]
In prospecting rock climbs in our own country, reconnoitring is practically confined to scrutinizing familiar faces for alternative routes or to orienting our own climbing in an unfamiliar district.
The first is a simple matter of good glasses, good sense and direct assault. In the second, there is still some room for general discretion.
We have to allow for a great difference in atmosphere as between Britain and the Alps. All alpine measures have to be reduced by about two-thirds.
We can generally assume that the north or northward inclined aspects of British hills will give us the best climbing. This judgment is subject to partial revision, according as we come to know better the local characteristics or the rock formation of the particular hill before us.
If the rock wall faces to the south, our prospect of good continuous climbing is reduced. Rocks facing south will be more disintegrated, as they will have been less protected from the sun and more subject to strong variations in temperature. If broken up or inclined on this side, they will be covered with verdure, which is offensive in itself and hastens the action of water on all the rocks it commands.
We have also to make sure of the lie of the strata, not only for convenience of hold, but also because on the side towards which the stratification dips the moisture fallen on the mountain will drain, and we shall have to look out for our principal enemies--wet rock, rock corrupted by moisture, and, in winter, an icing or glaze.
Our islands provide us with a great variety of rock structure and hill forms, and, according as we get to know the aspects of one hill of any local type, it is interesting to reconstruct the unseen aspects of its neighbours. Several good climbing cliffs were first found in this way.
The look of the outline will suggest the sort of climbing we shall find on the faces. We get further information from the nature and size of any scree slopes below a cliff. The presence or absence of verdure, and the sight of the belts, knots and surface minutiæ, tell us the rest.
All the local rock of the same aspect and in the same structural line will be similar, and may be bad; but if we can get at another aspect of it, on an opposite hillside, it may be of good holding character. For which reason rickety ridgelets may be faced across the valley by sober and admirable slabs.
Mist and cloud in Britain are our frequent companions. Mist may do us good service by throwing an unsuspected ridge or pinnacle into relief. But as a rule the alterations which cloud and fog effect in mountain details falsify rather than reveal. Their use is to place a greater value upon the fidelity with which previous reconnoitring has been conducted, and its result remembered, if we wish, in mist, to arrive at an intended climb at all, or to make descent into the right valley on our return. Not impossibly they are sent by nature to complicate what is otherwise the over-easy mountaineering training of our hills; to handicap the specializing gymnast, and to enforce the practices of observing detail, using the compass and map, and exercising judgment, memory, and the precious sense of direction.
THE HALF-SEEN
In the Alps or unfamiliar regions, to discover the truth about what may be termed the half-seen,--that is, about formation or detail which should be visible but for foreshortening, distance, angle or light,--new snow is again our best auxiliary. Its presence suggests, even emphasizes, much that is unsuspected. Seemingly straight ridges are shown to be crooked, and plain faces rough. It helps us with light in hidden corners, and annihilates distance.
Otherwise we have to use days of driving cloud, or wait for the morning or evening moments of thin mist, when the drift lies across the face or through the ridge, and picks out its angles, features and perspective. Mists will often reveal the existence of ridges and pinnacles, whose separation from the face behind is undiscoverable as seen in front or in clear light.
Of more frequent service are the hours when the sunlight falls across the face from the side, and the protuberances and hollows jump into stereoscopic clearness in shadow and the modifications of light. Invisible snow depressions, bosses and foreshortened angles of rock slab or ledge are cheerfully betrayed by the veracity of cross-shadows; and points and lines of obstinate sunlight, which remain salient and surprising after the sun has deserted all the rest of the seemingly even surface of snow or rock, proclaim to us unexpected inequalities and therefore possibilities of passage.
In cases of outside difficulty upon rock, where we are reconnoitring some great rock wall, of a granite or dolomitic type, we can generally make sure of the vertical rifts and clefts from below; but the presence or size of transverse fractures or belts is hidden from us. In this case assurance as to what has been only half-seen can be completed if a downward view of the rock, or of its local type, is also obtainable. The information is best secured from the summit of the peak itself, reached by another route, and many great first ascents have owed their discovery and safe accomplishment to such complementary inspection. Only a short section need be in sight from above in order to indicate the general character of the cross belts, and the last section on such peaks is always the more important to examine, as it will generally be the severest in its details. But even without this local visitation a downward or oblique view of any section of the face, or of an allied or neighbouring wall of similar structure, will give adequate information, and convert the half-seen into the two-thirds made certain.
A familiar instance of the use of such inspection would be almost any great Welsh cliff or Irish sea cliff. Seen from below, it appears to be continuous steep slabs, with only vertical cracks for the climber; seen from above, it looks a jumble of vague cross-terraces of grass, snow or rock, hardly offering a chance of good articulated climbs. Both estimates would be false. Only by collating the two points of view can a fair judgment of the character of the climbing be formed. A number of delightful climbs, of late discovery, have owed their neglect to the fact that they were only easily visible from a single aspect, and that this produced an abiding false estimate of their quality. The importance of securing corrective views, from different angles, be it only of a section of a proposed route, or of a passage of similar character more conveniently situated, attaches also to our inspection of the half-seen on big ridges. With points to remember in such inspection I have already dealt.
It does, in fact, belong not a little to the reasoning from the seen to the unseen; to which more metaphysical division of reconnoitring it leads over.
THE UNSEEN
The investigation of the unseen is a chief concern of mountaineers in new regions. But it can also be of service to the expert, in examining even a peak he knows well, to ascertain for him the condition of its invisible side on a particular day.
As I have said before, it is possible only to indicate where signs may be sought, and what relative differences the expert eye may discover and convert into information.
The mountaineer, after inspection of the near side of a ridge or summit in a big range, wishes to supplement this knowledge by the discovery of the character or general formation of the unseen side. He wishes to know whether it will give him snow of easier progress, or a subordinate ridge for better assault or descent; also whether he can look for clear rock on the far side, to assist his ascent of a ridge unfavourable in its visible aspects, or whether he must be prepared for ice slopes.
The first conditions for the inspection are experience, good glasses, clear sunlight and no recent snowfall. Also, if he wishes to confirm or increase the detail of his observations, he must be prepared to spend a whole day of good light, with the sun aiding him from different points in the sky.
As he looks over and across his high ridges from some distant view-point, in good sunlight, the mountaineer is able to distinguish several different kinds of sky, according to the different character of the unseen surfaces from which the sunlight is being reflected upward on to clear atmosphere or on to low clouds.
The Snow Sky.--This he will find has a distinguishable tint, identifiable by the practised eye, as different on a given day from the normal coloration of the sky above as is the light reflected from different qualities of steel, or from silver as compared with electroplate.
If the sky seen over his ridge is purely a snow sky, of uniform appearance, it is just to assume that the unseen side of the ridge consists of large snow slopes, and rises at a comparatively gentle angle, since we know already that upon broad surfaces, at a steep angle, snow can only rest while it remains new and adhesive.
If, again, the sky above is purely a snow sky, but is traversed by a band of slightly modified quality or tone, leading away from the eye, there will exist on the far side a correspondingly inclined great snow ridge, from one side of which the sun, in a given position, will be reflecting high light, but from the other, lower. By repeating the observation at different times of day, so that the light will have fallen and been reflected from different directions, we can confirm the existence of such a ridge, and may be able to locate its position and determine its magnitude with some accuracy.
A second and characteristic appearance is visible on the sky above the unseen side, if this far side consists of two large snow fields divided by a long rocky ridge extending away from us. We then have a snow sky divided by a band of sky which is not catching any reflected higher light, and which we may assume to be a ‘rock’ sky.
The Rock Sky.--If the whole expanse of the sky above is seen to have a uniform and normal tone with no local alterations, such as would be produced by partial snow reflection, then the unseen side will consist of a large wall of rock--probably, in such case, steep rock.
Under favourable conditions, a very practised observer may detect in a uniform rock sky a band of slightly modified tone going away from the eye on the far side. This will be produced by another great rock ridge extending in the corresponding direction. By watching the sky above this ridge, and observing the differences produced by the reflections of light at different hours from its different aspects, we may even be able to discover to our satisfaction whether the invisible ridge is all rock or has one side covered with snow.
The Ice Sky.--Dry glacier or large fields of ice betray themselves upon the sky in a slightly greyer tinge, distinguishable more by contrast than by an absolute tone from a snow sky under the same conditions.
There is also a ‘water’ sky--the unmistakable look in a sky which is reflecting great unseen sheets of water; but its identification is more familiar and of more service to arctic or desert travellers than to mountaineers.
Apart from these larger sky signs there are some more local indications that are of particular value to the climber. The appearance of the sky as seen across the ridge will in most cases give us evidence of a mixed character--that the unseen side is partly rock, partly snow. It is thus essential to know, if we propose to use the ridge we are prospecting for our ascent, whether the rock just over or on the ridge is bare or ice glazed, and whether the snow discovered on the far side rises up to the edge of the ridge or leaves a crest of clear rock.
If there are bare rocks close up to the edge on the unseen side, these will be at certain hours heated by the sun, and a hot current of air will be ascending. The skyline above will have a wavering appearance, showing a band of darker tint between the ridge and the normal sky.
If there is snow close up on the far side, the air will not be disturbed, and the skyline will be steady and clean.
If the rocks beyond are free from snow but glazed with ice, the skyline will remain undisturbed, but it will have a brilliant glistening appearance in strong sunlight, like a strip of polished blue steel. This last indication, if the eye can learn its significance, may often be of service on climbs where the unseen mountain structure is already known, but when there is uncertainty as to the actual condition of the rocks on the day. Many fruitless ascents might have been saved if the ice glazing on such unseen sections of a ridge could have been detected in time.
Some of these appearances may even be recognized in photographs, if they have been taken under the right conditions and left untouched. By watching a given section of ridge, while the sun is moving across the sky, all a sunny day, and by using a map at first to discover what the different sky signs as they become visible actually mean, and also how much they reveal of the unseen topography as displayed in the map, it is possible for some men to train their sight to discriminate fairly closely between a number of even more complex signs, and to ascertain actual details as to the character and direction of unseen walls and crests, the location of unseen snow summits, and the length of far ridges.
The process, in practical application, is of course throughout assisted, corrected, and its lines of observation suggested by the nearer features which the expert reconnoitrer already has in sight. For an observer who knows the forms usual in the type of mountain before him, and who has the local features, on the side visible to him, to indicate still more closely what he may look out for, the interpretation of the meaning of sky signs presents fewer alternatives, and the conclusions drawn from them can be far more detailed than would seem possible were his reasoning about the unseen based only upon one group of evidences.
Final success in reconnoitring depends upon our ability to put together, in order of their relative importance, all our assembly of large and small evidences. Experience is able to deduce the small from the large and to reconstruct the large from the small; and confirmation of the truth of our deductions, from the seen or the unseen, comes when two such lines of evidence meet: when the detail which we discover in a single quarter confirms the speculations that we have based upon our experience or on our interpretation of larger evidences, or when our induction from a number of small visible indications is proved correct by some revelation in a greater sky sign.
For a mountaineer who has to convert his observation of distant objects and signs, of a size altogether incommensurate with his own, into terms of a possible advance for his eight-foot reach or four-foot stride, no evidence is too big or too small;--and this especially because the big, in mountains, repeats itself in the small with timely consistency. A good mountaineer might almost claim to be able to construe a single favourable sky sign, under certain conditions, into the assurance of his atom-like advance up the infinite invisible detail of an unpromising-looking mountain giant.
Sunny days, patience and good glasses are first conditions for his task. The same glasses should always be used. A type should be selected that gives enhanced stereoscopic effect. Above all, the sight of the eyes must be equal, or corrective glasses should be worn. Many men never discover even what they ought to be able to see, until they learn that their eyesight is, if only slightly, astigmatic, and use spectacles for their reconnoitring.
Reconnoitring is not merely the preparation for a single day or for a particular climb. A mountaineer has to learn to see and to record all day and every day, not only distant signs for future use, but each and every detail of his surroundings. The detail may be forgotten, but its accumulation will gradually form in his mind a mass of general precedents and of knowledge of the characteristics of particular shapes and structures. This will remain with him, and will return instinctively to aid his judgment when some cognate detail presents itself to be interpreted as a piece of solitary evidence. As a last personal illustration, I may recall that one of the pleasantest new ascents in my recollection was the outcome of a simple reasoning from a detail in the seen to the memory of the unseen: the sight of a layer of excellent snow, covering for the time the usually bare slabs of one wall of a peak from which we were descending, revived the recollection that on a famous peak in another valley was a similar wall of identical aspect and character, as yet unascended on account of its normal impracticability. Without further examination we made the attempt upon it, and the speculation was confirmed in the cheeriest manner.
If care so constant that it dominates alike the exhaustion of failure and the more dangerous enervation of triumph is essential for our safe climbing, observation so continuous that it becomes unconscious is as necessary for our fortunate designing. Its habit may profit us by more even than by momentary success. For a mountaineer may read a sky sign only for the promise that it brings him of the morrow’s exercise; but he has learned to see it, and with the power of sight he has opened a new world of pleasure. It was the first scientific student of the form and reflection of clouds, of the structure and relation of hills, who was the first understanding prophet of their significance for art and imagination. The more we can learn to see or to reconstruct of the mountain forms visible or invisible about us as we climb, the more vividly will memory interpret their meaning for our lives when we are no longer among them. If we are of a mood to use both sight and its interpretation as servants of our spirit as much as of our performance, we may discover a reflection from the mountains that will permanently colour our thought. There is a reassurance no less for our journey through the years than for our march of a day in the perception that oncoming shadow, by its very quality of darker relief, can reveal to us some unsuspected and relenting aspect in the daunting precipice across our path; and a twofold message, for our mind even more than for our mountaineering, in “the light of the unseen snow-field, lying level behind the visible peaks, sent up with strange reflections upon the clouds; an everlasting light of calm aurora in the north.”
IX. MOUNTAINEERING ON SKI
BY ARNOLD LUNN
Winter mountaineering may be said to date from Mr. Moore’s crossing of the Strahlegg and Finsteraarjoch Passes in January 1865. The first big peak to be climbed in winter was the Wetterhorn, which was ascended in 1874 by the Rev. W. A. B. Coolidge and Miss Brevort; a few days later this party climbed the Jungfrau. These brilliant expeditions set a fashion which was, however, only followed by a select company of mountaineers, among whom a place of honour must be given to Mrs. Le Blonde. It was not until Paulcke crossed the Oberland at the end of 1897 on the ski that winter mountaineering began to be a popular sport. To wade up a big peak in deep snow on snow-shoes or on foot only appealed to a minority, but the number of those who were attracted by the chance of combining mountaineering with ski-ing steadily increased.
The English were slow to follow the new fashion; the number of British ski-runners who have a long list of glacier ski tours to their credit is still small, but abroad hundreds of experienced mountaineers have explored the High Alps on ski, and abroad the advisability of using the ski in the High Alps has passed beyond the limits of discussion.
The time is coming when most alpine huts will be provided with ski. A steadily increasing number of mountaineers realize that such peaks as Monte Rosa or the Zermatt Breithorn provide excellent ski-ing at all months of the year, and that the trouble of dragging a light pair of summer ski to the summit is well repaid by a magnificent run down to the hut.
There is no month in the year in which the writer has not enjoyed first-class ski-ing, and there is no season in the whole alpine calendar in which ski cannot be used on the loftier snow peaks in the Alps. Ski have come to stay as an indispensable adjunct to mountaineering. To the rock climber the ski are perhaps mainly useful in bad seasons; if the weather in summer were uniformly good the enthusiastic rock climber would have little use for the ski. But long spells of bad weather are not unknown, and many a climber who has engaged a guide or a couple of guides for a month has spent a week, a fortnight, or in some cases even longer without climbing a peak. I venture to assert that if he took himself and his ski to a club hut he would at least have the satisfaction of making good use even of an afternoon’s fine weather. I remember once finding myself at the Egon von Steiger hut during bad weather. It snowed all day and all night, and cleared at ten o’clock the next morning. Two parties on foot attempted the easy Ebnefluh. Both were driven back after a very brief struggle with deep soft snow. Myself and a friend reached the summit on ski in more or less normal time, and enjoyed a wonderful run back to the hut, where the disgruntled foot-sloggers had spent the day.
Let the rock climber learn to ski, and when the big rock peaks are deep in snow he will be able to snatch a Monte Rosa or Breithorn from the first fine day. In bad seasons individual fine days are often sandwiched between two or three days of bad weather. Such isolated days are useless to the foot-climber but invaluable to the ski-runner.
[Sidenote: Technique.]
I cannot spare the space to explain the technique of ski-ing.[18] Here I need only attempt to dispel a lingering belief, that dies hard, to the effect that there is one technique for ordinary ski-runners and another for mountaineers. This curious superstition is the last relic of an exploded system of ski-ing taught by an Austrian called Zdarsky, the main effect of which was to encourage timid, slow and clumsy ski-ing. The ‘Lillienfeld’ ski were short, and made straight running very difficult and turning very easy. The Lillienfeld system taught people to ski very quickly by dodging all difficulties and encouraged a free use of the stick. It was a bad system, and is now quite discredited; but there still lingers a curious belief that the Norwegian style may be all very well for small mountains but is too dashing and insecure for the High Alps. As a rule, glacier ski-ing is far easier than ski-ing among the lower mountains; the most difficult of all ski-ing country is wooded country, such as extends for miles round Christiania, the home of the ‘Norwegian style.’ Let me therefore urge the reader to master the free Norwegian style, to make all his turns and swings without the aid of the stick, and to acquire a free and dashing style. The mountaineer even more than the low-level ski-runner should have complete control of his ski, and complete control is impossible unless you have learned to control your ski not by means of the stick, but by means of the ski themselves.
[Illustration: SNOW WAYS [JEAN GABERELL]
There are a few occasions on which the use of the stick is permissible on tour; but it is so dangerous to begin by using the stick as a brake, that I would advise the beginner NEVER to use the stick until he has at least passed the ‘THIRD-CLASS TEST’ which is held from time to time in all ski-ing centres patronized by British runners.
Furthermore, though of course it is absurd to take risks in the High Alps, occasions often arise where speed means safety. With bad weather or night approaching, the man who can run fast stands more chance than the man who can not, and, consequently, the higher your speed consistent with safety the better your chances. Now, a high speed consistent with safety can only be maintained by those who have lost no chance on small expeditions of raising the speed at which they feel comfortable, and this, again, can only be achieved by running just a little faster than is quite comfortable.
In the High Alps a reckless runner, who is always falling, is a danger to his companions and himself, but a man who is quite incapable of a fair speed is always a nuisance on tour, and may sometimes prove a danger. Steadiness is the first requisite in the High Alps, but speed is by no means unimportant. Any man with average balance and nerve, if he is properly taught, can learn to run steadily and to make slow turns on average snow at the end of a fortnight. To become a really expert ski-runner is, of course, another matter, but some of the finest ski-turns in the High Alps have been carried through with success by men who were not even third-class runners. Let the mountaineer learn to ski and take such chances as a snowy summer may afford. In a few hours he will begin to enjoy ski-ing, and his enjoyment will steadily increase with his experience. It is easy to become a third-class ski-runner, and very well worth while taking sufficient trouble to become a second-class runner. First-class ski-ing is, of course, not within the reach of all.
In order to make much that follows comprehensible to the reader, who, though a mountaineer, has yet to become a ski-runner, a short definition of the ski-ing turns and swings is necessary.
The object of every ski-runner is to approximate as nearly as possible in his course to a straight line between the point of departure and the goal. Obviously this ideal is impossible of attainment save on comparatively short open slopes, which can be taken straight. Hence the regrettable necessity of turns and swings which, unlike skating turns and swings, are not an end in themselves, and are only incidentally beautiful and graceful to execute and to watch.
There are three principal turns or swings: the Stemming turn, the Telemark, the Christiania.
Each of these turns can be used either as a stop turn (i.e. in order to stop more or less suddenly), or as a means of linking one tack to another. For instance, a slope may be too steep to take straight; in this case the good runner descends in a series of linked curves.
According to the condition of the snow, he will make these linked curves either by means of the Stemming, the Telemark, or the Christiania turns.
The Stemming turn is the easiest and slowest turn. It is the key to alpine ski-ing, and can be employed on snow on which a Telemark or linked Christiania would be either difficult or impossible. The beginner should try to combine Stemming with Christianias, to begin his turn as a Stem and to finish with a Christiania. This swing, which is sometimes called a Stem-Christiania or a ‘Closed Christiania’ (as opposed to ‘Open Christianias’), or by a natural abbreviation a ‘Closti,’ is the most generally useful of ski-ing swings.
The Lillienfeld system placed exclusive reliance on the Stemming turn and dismissed the other two as fancy tricks. This was absurd, for in many kinds of snow the Telemark or Christiania is much the more useful manœuvre. Either of these latter turns can be executed at a very high speed, whereas the Stemming turn cannot be done at a high speed.
The Telemark is mainly useful in deep soft snow or in soft breakable crust; in either of which the Stemming turn and the linked Christiania is difficult or impossible.
The Christiania, as a stop turn, is the safest method of stopping at high speed. Linked open Christianias are not easy to master, but are very satisfactory when mastered. Wherever a linked series of Christianias can be executed, linked Stem-Christianias are easier, and safer. The power to make a series of continuous non-stop turns with the Christiania marks out the expert; nothing is more beautiful than fast descent on glacier snow, film crust or crust slightly softened by means of a series of swift-running Christianias.
For the High Alps I consider that the Stemming turn and the Christiania should always be used in preference to the Telemark, excepting in very deep soft snow--rare in the High Alps--or in soft breakable crust.
The Telemark is a one-foot turn; all the weight is on the leading foot; consequently the Telemark is less powerful and less sure than the Christiania, which is a two-foot turn. Furthermore, the falls resulting from a Telemark which has gone wrong are more dangerous than from any other turn. From a faulty Christiania or Stemming turn one is usually thrown backwards or sideways against the slope; from a faulty Telemark one is often thrown on to one’s head or outwards from the slope. Further, the ski have a nasty habit of crossing behind in a badly timed Telemark.
To sum up: Use the stick as little as possible. Make all your linked turns by Stem-Christianias, except in deep soft snow or breakable crust, where the Telemark should be used. For a sudden stop use the Christiania in preference to the Telemark.
[Sidenote: Equipment.]
In addition to the ordinary mountaineer’s equipment, the ski-runner must have ski, sealskins, ski-sticks and repair outfit for ski.
I have no space to advise on the choice of ski, but I might warn the reader against the common illusion that ski for mountaineering should be markedly shorter than ski for short tours. They should be a couple of inches shorter, but very short ski should not be used save in the summer. I have used the longest size obtainable (2·36 in.) for quite long tours, and the next longest size (2·31 in.) in the High Alps.
Sealskin are detachable, and are fixed on to the ski to prevent the ski side-slipping while climbing a steep slope. Ski-ing boots are bigger than mountaineering boots. They should be nailed--lightly nailed, of course, but on no account entirely nailless. The nailless ski-ing boot is a superstition imported from Norway, where the hills are milder in gradient than in the Alps.
For all glacier tours crampons, or, to use another word, ‘ice-claws,’ should be taken. Eight-pointers are best, though good work can be done with six-pointers. The small four pointers are most insecure and uncomfortable.
For all further details as to equipment the reader may consult my book Cross Country Ski-ing.
THE ALPINE CALENDAR
The first winter snows usually fall in October: excellent ski-ing is often obtained at the ordinary winter sports centres in October. Glacier tours should certainly not be attempted before December, as the danger from crevasses is at its maximum in October and November. January and February are the best months for ski tours up to about ten thousand feet. The winter proper is NOT the best season for glacier ski tours, though most of the classic ski tours in the High Alps have been carried out between December and the end of February. Good ski-ing can be obtained at low levels well on to the end of April, and sometimes even later. As a rule, the snow lies down to about five thousand feet on north slopes well on into the middle of May.
MAY AND JUNE ARE THE BEST MONTHS FOR GLACIER SKI-ING, though excellent ski-ing may be obtained throughout the summer. There is no month in the year in which the High Alps do not yield good snow, but the best all-round months for mountaineering on ski are undoubtedly May and June.
SNOW CRAFT
The expert cross-country ski-runner must not only be a fast and safe runner on all kinds of snow and ground, but he must also possess a thorough knowledge of snow craft. Unfortunately, there are nine ski-runners whose Telemarks are perfect for one whose knowledge of snow is even adequate, and the number of those whose understanding of snow in all seasons of the year is really expert is indeed small.
Snow craft in winter and in spring is even more complex than in summer, and requires a special study of its own. Even the most expert guides whose knowledge of summer snow leaves nothing to be desired require considerable winter experience before they are thoroughly competent to lead a party among the High Alps in winter. The same is true of spring; each season, in fact, requires a separate study.
The ski-runner needs to possess a more exact knowledge of snow than that which the foot-mountaineer requires. A mountaineer on foot is mainly interesting to discover whether the snow is hard enough to walk uphill without sinking in, and whether the snow is likely to avalanche. Hard snow, soft snow and avalanche snow are the three main categories in which the foot-mountaineer divides snow. He need not bother with all the delicate gradations of value that distinguish snow which is so hard that it will not take a Stemming turn, and snow which, though hard enough to bear a foot, will yet take a Christiania or even a Telemark.
The ski-runner who neglects snow craft is severely punished for his carelessness. He runs into fast and sticky snow and pitches heavily on his face, or from soft snow on to hard snow and falls heavily backwards. Even the least observant ski-runner soon realizes that an elementary knowledge of snow is essential to his comfort and his safety. His knowledge of snow needs to be instinctive. On foot a man has time to probe and to examine, but on ski he has to diagnose the snow while travelling at a high speed. He has to possess an accurate sense of direction so that he can foretell the changes of snow that occur when travelling from, say, a north-east slope on to an eastern slope, or an eastern slope on to a south-eastern slope.
Quite as many bad ski-ing falls are caused by deficient snow craft as by deficient balance.
Precisely because even the most casual ski-runner is bound to learn from the past experience of nasty falls, ski-ing inevitably teaches even the most unobservant some knowledge of snow craft. A ski-runner cannot hand over the whole strategy of the day’s campaign to a guide. He must think for himself and study for himself. In summer the real business of climbing usually begins when the glacier or the summer snowline is reached, but in winter a ski-runner can kill himself in an avalanche within an hour of the hotel. Snow craft begins in winter at the hotel door.
The careful study of snow is a fascinating branch of nature study. More can be learned from books than the reader might imagine. Once a ski-runner has grasped how snow is affected by altitude, orientation, wind and sun, he is in a better position to profit by his knowledge in practice than if he was forced painfully to unravel the laws of snow by personal observation. In the early days of ski-ing in the Alps the guides themselves were completely ignorant of the main laws of snow in winter. They are still, for the most part, ignorant of the subtleties of spring ski-ing, which is much more difficult to understand than winter ski-ing. In winter, if a snow slope holds good snow in the morning it will probably hold good snow throughout the day, but in spring the same slope goes through a regular cycle of changes. It may be unskiable at dawn, yield perfect ski-ing at midday, prove absolutely unsafe at three in the afternoon, and yield good running again in the evening.
To time a descent accurately, to forecast from a knowledge of the orientation and altitude of a given mountain that it will yield perfect ski-ing at a given hour, is to know one of the most satisfactory intellectual pleasures that the mountains afford.
WINTER SNOW
There are certain forms of snow which are characteristic of certain seasons. ‘Powder snow,’ for instance, is normal in winter and uncommon in the late spring; none the less powder snow is often found even in summer, just as certain forms of snow which are characteristic of spring or early summer are occasionally found even in midwinter. ‘Winter snow’ must then be taken to mean the kind of snow which is common and characteristic of, but not limited to, winter.
[Sidenote: Powder snow.]
In winter a normal snowfall is accompanied by a temperature below freezing; snow that falls with the temperature just above freezing usually descends in the form of sleet. Fortunately, such conditions are not common.
Snow will even fall when the temperature registers a degree or two of thaw. I have known dry snow fall with a temperature of two degrees above zero--centigrade, at a height of 5500 feet above the sea. Similarly, as icemakers know, water will freeze on a rink even when the temperature is above freezing-point.
The explanation for this anomaly may be sought in the well-known law that pressure lowers the freezing-point.[19] It seems a natural deduction that diminished pressure will raise the freezing-point. 0° centigrade is the freezing-point of water at sea-level. Under a pressure greater than that of the air at sea-level, the freezing-point is lowered so that the bottom of a glacier will be in a condition of liquefaction at a temperature below freezing. It should follow that an air pressure less than that of the air at sea-level should raise the freezing-point; or, in other words, that at any point above sea-level the freezing-point should be higher than zero. From my own observations I believe that water will freeze and rain turn to snow when the temperature is 2 degrees centigrade above zero at a height of 5000 feet.
Fortunately, the normal snowfall is accompanied by a temperature below freezing, for if the snow is on the point of turning to rain, it forms a crust when the temperature falls. A normal dry snowfall takes the form of small hexagonal crystals. Newly fallen snow is not compact, and contains a great deal of air, which slowly escapes as the snow settles, so that after a day or two the new snow has lost nearly a half of its apparent depth.
New snow is very soft and slow, but gives good running on steep slopes; though, of course, long steep slopes are liable to avalanche. Good running is also often obtained during a snowfall by choosing south slopes, previously covered by a hard crust; for there is nothing pleasanter than two or three inches of snow on hard crust, and during a gentle snowfall it is possible to enjoy quite good sport on such slopes. In general, expeditions--even quite short ones--are impossible till the snow stops, and unsafe for a day or two after a heavy fall. Newly fallen snow sticks badly in the sun even if the temperature is well below freezing.
Once, however, that the snow has settled it soon gives perfect running. One night’s really hard frost is sufficient to produce excellent snow. Powder snow remains good almost indefinitely in winter on northern slopes, provided it is not spoiled by wind. It steadily improves. In sheltered places the crystals gradually grow in size so that sometimes you find large leaf-like formations, which rustle under the ski like autumn leaves. Such snow is a dream of paradise.
Powder snow is the ideal running surface. It is equally good for straight running and for swings. In deep soft powder the Telemark is the best swing, but in fairly compact powder any turn or swing is easy and safe.
The ski-runner who visits the Alps in winter, and has good luck, may run for day after day on perfect powder. He is in danger of thinking himself a better runner than he is. If he concentrates on Telemarks, the first tour in the High Alps, where he will meet varieties of hard and soft crust, will find him out badly. He should therefore make a point of spending a day or two on south slopes so as to master the Stemming turn on hard snow. If he is getting pleased with his Telemarks, let him try a Telemark on the soft breakable crust to be found on south slopes at midday, and if he can do a series of fast-linked Telemarks in such crust, he may then return to his powder snow with a good conscience.
[Sidenote: The Effect of Wind on Powder Snow.]
Snow which is spoiled by the sun is never quite impossible, and is always curable by a hair of the dog that bit it; in other words, by another and stronger dose of sun. But snow which has been wrecked by the wind is the despair of the ski-runner.
The wind does not affect snow that has once been crusted, so that wind-swept snow is almost unknown in spring. The favourite victim of wind is precisely that light, dry powdery snow which is so common in winter.
The effect of wind depends on three factors, the strength of the wind, the time during which the snow is exposed to the wind, and lastly the type of snow exposed to the wind. Powder snow is the most sensitive, the quickest to spoil and the most trying when spoiled. Hard crust is entirely unaffected; heavy wet snow is very little affected.
A light wind produces on powder snow the markings which are known as ripplemark, a term which has been applied by scientists to the rippled effects which can be traced, not only in snow, but also in sand, and even in clouds which have been influenced by wind. Sand and snow behave very similarly under the influence of wind. A slightly stronger wind, or a wind blowing for a longer spell, produces caked powder, which is dense and compact, but has not quite lost its powdery quality. The ski sink in to a depth of an inch or more, and though fast running is dangerous and apt to produce broken ski points, a good runner can derive much pleasure from caked powder, and can force linked Telemarks without much trouble. The third stage in the deterioration of snow occurs when the wind produces a hard crust. Windboard is hard and slippery, but so long as it is not varied with soft patches of sticky snow or of breakable crust, windboard yields a surface which may annoy the novice but which should not prove, at any rate on slopes of moderate gradient, too troublesome to an expert who has mastered his hard snow turns. Windboard is common during the winter months in the High Alps; in appearance and texture it is not unlike the hard marble crust, which is found on south slopes after a long spell of fine weather, but it is vital to discriminate between windboard and marble crust, because the former may sometimes break away in slab avalanches whereas the latter never avalanches. Windboard betrays its origin by ripple markings, sometimes faint but seldom invisible to the practised eye. Windboard is often varied by pockets of sticky snow.
If wind produced nothing worse than caked powder or windboard, the ski-runner would have less cause for complaint. Unfortunately the wind often produces horrible surfaces which resemble each other only in their general unsuitability for ski-ing. Skavla is the generic Norwegian name for wind-swept snow, and skavla is common on the exposed fjords of Norway and Sweden, where it attains a degree of unpleasantness seldom matched in the Alps. Skavla varies. Sometimes skavla consists of patches of glittering ice varied by treacherous pockets of sticky snow; sometimes a breakable trap crust interspersed with windboard; sometimes waves of hard, icy snow which occasionally attain a height of two feet or more. The prevailing wind determines the direction of the waves and acts in precisely a contrary fashion to that of wind on water; for wind on snow has a burrowing effect, and forms these waves by excavating and eroding a slope, gradually forming a series of steps. In other words, whereas on the sea the wind will be found to be blowing up the longer slope of a wave, on snow the wind will have been blowing against the short steep side of the snowy waves.
To sum up: The effect of wind on powder snow is always bad. The stronger the wind and the longer that it blows, the worse the snow. Hence in winter avoid exposed slopes and seek out sheltered valleys. The summit slopes of winter mountains will usually be spoiled by the wind, which is one of many reasons why spring is so superior to winter as far as ski-ing in the High Alps is concerned.
[Sidenote: The Effect of Sun on Powder Snow.]
Powder snow acquires a crust if it is exposed to wind, to sun shining at a sufficiently direct angle, and to an air temperature above freezing. Wind alone has the power of forming crust without a preliminary melting of the surface. I do not know why this should be so, but no doubt the reason is to be found in the law that pressure lowers the freezing-point, so that the increased pressure caused by wind lowers the freezing-point, or, in other words, produces the effects of a thaw at the point where the wind acts even though the general air temperature may be well below zero centigrade.
At any rate, sun, wind and thaw are alike in producing a surface crust.
The effect of the sun depends mainly upon the angle of inclination. In midwinter, snow will remain unaffected by the sun on northerly slopes even though they receive several hours of sunshine in the course of the day.
In fact, in midwinter eastern and western slopes retain powder snow for a very considerable time, while a slope that is a few degrees north of west or a few degrees north of east retains powder snow throughout the winter, always providing that it is not exposed to wind or to thaw.[20]
I use the term ‘thaw’ to denote a general air temperature above freezing as opposed to the purely local melting caused by the sun’s rays, which may be, and in fact normally is, accompanied by an air temperature in the shade of several degrees below freezing.
The thermometer will often be registering more than ten degrees of frost in the shade and twenty or more degrees of warmth--centigrade--in the sun. It is, as icemakers know, quite common to find a belt of cold air, two feet in height, just above the snow and just below a strata of warm air several degrees above freezing-point.
In normal winter weather you may be uncomfortably warm in the sunshine, and yet the sun has no power to affect powder snow on any slope which has not a touch of south in it.
The steepest south slopes are the first to lose their powder snow. Afterwards, the gentler south slopes follow suit. Towards the end of February western and eastern slopes begin to crust. In March due north slopes still hold powder,--at any rate above 5000 or 6000 feet,--but slopes which are only a few degrees north of east or of west begin to crust. Finally, the level outruns get crusted, then the gentle due north slopes, and last of all steep north slopes.
Of course at high altitudes winter conditions prevail until well on into April.
In midwinter good ski-ing is usually to be had on south slopes for three or four days after a snowfall, though steep due south slopes soon crust. The time during which gentle south slopes or slopes which are just south of west or east will hold powder depends on the general air temperature and on the altitude. I have known pretty steep due south slopes hold powder below 4000 feet for three days of cloudless weather, but the temperature was about 15 degrees centigrade below freezing.
This is, however, unusual, and south slopes soon crust up even in midwinter. The sun melts the snow by day, and the melted snow refreezes at night, producing a crust. Such a crust will, at first, be soft and breakable.
Soft breakable crust is not a bad running surface. It is quite true, i.e. does not vary in pace from one place to another, and is usually soft enough to enable the ski-runner to make Telemark swings, either stop or linked, without much difficulty. Sometimes the crust is harder, and in this case the jump-round or quersprung is the only possible manœuvre.
A peculiarly villainous form of crust, fortunately rather rare, is known by the appropriate name of Trap crust. This crust is perfectly solid at one spot, and bears the weight of the ski without breaking, only to crack a few yards lower down. The ski-runner skids with great speed over the hard crust, only to be pulled up suddenly as his ski break through the soft crust below.
Trap crust is more usual in spring than in winter, especially on slopes which change in direction, so that the ski-runner passes from snow which has been sufficiently thawed to form a hard solid crust at night to slopes which have only been superficially melted. Trap crust is only found after fairly heavy falls of snow which require considerable time to form a solid crust. As a rule, trap crust covers a foot or more of powder snow.
To return, however, to more normal winter conditions. Under normal conditions the snow on south slopes in winter is gradually transformed into crust.
This crust is at first soft and breakable, but the continuous process of melting and refreezing gradually produces a solid unbreakable crust.
Unbreakable crust, as the ski-runner soon discovers, varies greatly in quality from hard crust which is so hard that the ski slip sideways without obtaining the least grip, crust which on any slope but the most gentle is almost unskiable, to the other extreme, crust which though quite hard and unbreakable is rough enough to permit even a Telemark and to make Christianias and Stemming turns delightfully easy.
The solid crust formed in winter is usually very hard and slippery before the sun strikes it. This crust is known as Marble Crust. You find marble crust on southern slopes in winter, and at high altitudes in spring. It is common in the High Alps. Even at the very end of April I have known a slope at a height of 12,000 feet remain hard, slippery and unsoftened for some little time after the sun had struck it because a bitter north wind had lowered the temperature several degrees below freezing.
In mid-winter a slope of marble crust will yield good ski-ing after the sun has struck it, unless the air temperature is several degrees below freezing. Marble crust, touched by the sun, yields a surface which will puzzle the beginner but which is pure delight to the man who has mastered Stemming turns and Christianias. The excellent running that may be obtained on south slopes is too little exploited, for winter ski-runners are firmly convinced that good ski-ing can only be found on north slopes where powder lies.
Mid-winter may be said to last till the end of January. In February you often find perfect spring snow, Telemark crust, etc., on south slopes, and in February, as often as not, the best running is obtained on southern slopes. This type of running will be dealt with later.
[Sidenote: Summary of Winter Snow.]
Winter snow may therefore be summarized as follows. The normal winter snow which is found throughout the winter on northern slopes and occasionally on southern slopes is powder snow which is perhaps the ideal ski-ing snow.
Powder snow deteriorates under the influence of wind and sun. Wind is the more mischievous. A little wind does no great harm, and the expert can even ski with pleasure on the hard crust formed by wind, but the extreme action of wind often produces varieties of snow which are all but unskiable.
The High Alps and lofty summits in general being most exposed to wind will usually yield inferior ski-ing to sheltered slopes. The best ski-ing in winter will therefore seldom be found on the glaciers.
Snow also deteriorates under the influence of sun, which forms a crust. This crust, however, once formed is often improved by a further dose of sun.
Though the best ski-ing is usually obtained on north slopes, excellent ski-ing is often obtained on south slopes by those whose knowledge of snow craft is sufficient to time their descent and to choose their route accurately.
Abnormal conditions produced by Föhn and thaw are dealt with on pp. 417-422.
SPRING SNOW
We have seen that good ski-ing in winter depends largely on the absence of wind. A sudden thaw may also produce a disastrous result, for snow which has once been rained on and refrozen will remain covered with crust until there is a new snowfall.
The best winter snow is without rival, but spring snow is, on the whole, safer and less capricious. In normal spring weather all snow is crusted in the early morning, for the sun is powerful enough to melt snow even on northern slopes. But this spring crust, as we shall soon show, is much less troublesome than crust in winter and yields very fine ski-ing indeed. Wind, the great enemy in winter, has no effect in spring, for wind cannot affect hard crust, and if wind blows while the snow is falling a few days of strong sun will melt any wind-formed crust and produce exactly the same surface as if the snow had never been touched by wind. It should, however, be added that, in the early spring, wind, though powerless on snow which has once been melted and crusted, is a great nuisance if it blows on snow which is still powdery, as is usually the case for twenty-four hours or so after a snowfall; snow which has once been crusted by the wind has a very strong resisting power to the action of the sun; I have known south snow in March retain irritating effects of wind action after several days of strong sun that would have been sufficiently potent to melt any ordinary crust.
Spring ski-ing is, as a rule, delightful. Snow is troublesome in the intermediate stage between powder and crust. Once a crust is formed, the more often that crust is remelted and refrozen the better, as there is nothing better than old crystalline snow which has been through the mill of melting and refreezing again and again. Unless wet Föhn blows such snow will always retain its crystalline character, even when remelted by the sun, and will always yield good ski-ing. Of course in the late spring at low altitudes the sun is powerful enough thoroughly to thaw and drench the snow, and in the middle of May below 7000 feet wet snow in the middle of the day is unpleasant. But in March and April ski-ing on melted crust is wholly delightful. Incidentally the best ‘Spring snow’ is often found at the end of or in the middle of February on southern slopes.
From the beginning of March onwards all slopes, save those at very high altitudes, begin to crust over. The process is gradual on northern slopes. There is a period when the northern slopes no longer hold the dry loose powder of winter but have not yet begun to crust.
Spring powder is common on north slopes in March. It is denser than winter powder, and is not so dry. It is slightly moist on the surface, and much heavier. It yields, however, a first-class running surface, and will take any turn or swing. Its main objection is the fact that it is peculiarly liable to avalanche.
Gradually, however, Spring powder disappears, save at great heights, and all slopes are covered by crust. In the afternoon the crust is melted, and the snow is soft and wet on all slopes. At night the snow is refrozen.
The normal cycle, then, of a normal spring (say April, at altitudes between 3000 and 9000 feet) is as follows: Hard crust at dawn; crust superficially softened between sunrise and midday; soft melted snow in the afternoon; soft breakable crust as the sun loses in strength; and solid hard crust after the sunset.
First let us consider the hard crust usually found at dawn.
This differs materially from the marble crust of winter, and from any of the crusts formed by wind action. It is, as a rule, slightly softer. What is more to the point, it is rougher. The surface of normal spring crust is perforated by numberless little holes. Sometimes these holes are quite small, mere pockmarks, sometimes they are as large as half-crown pieces. It is the presence of these holes and the roughness of the crust that makes steering easy, so that control is not difficult, and linked Christianias or Stemming turns are within the power of the good runner.
Perforated crust, in fact, is a delightful running surface. It is common at low altitudes in March, at moderate altitudes in April, and is normal in the High Alps in May, June, July and even August.
Film crust is found in May and June on the glaciers, and occasionally at low altitudes in April. It forms a delightful running surface. Unlike marble and perforated crust, it is not quite homogeneous. It is composed of a hard under-surface of solid crust, covered by a very thin, soft, and transparent film of ice, which glistens in the sun like burnished silver.
This film of soft ice is shorn away as the ski begin to come round on a turn. It provides a splendid purchase, preventing effectually all side-slip, and yet not sufficiently strong to make turns difficult.
Film crust is admirable for fast straight running, because at any moment the pace can be regulated by a swift turn. There is nothing finer than a run down the glaciers in the early morning on film crust.
We have seen that the cold nights of winter produce marble crust, which is hard and slippery. Marble crust is the kind of surface which needs crampons or a chip with the axe if it is climbed on foot.
Further, marble crust, and all forms of crust produced by winter winds, yield a very unsatisfactory surface, too slippery to give good purchase.
We have seen that the milder nights of April produce perforated crust which is much rougher and gives good ski-ing, while the even warmer nights of May and June produce film crust in which Christianias and Stemming turns are easy and safe. In fact film crust gives such a wonderful grip that even Telemarks are possible.
From this we deduce the following law:
Provided the night’s frost is sufficient to produce a solid unbreakable crust, the crust will give the best ski-ing when the frost has been least severe.
In other words, “THE MILDER THE FROST THE BETTER THE CRUST.”
This rule is important. It often happens in spring that one has to start down before the sun has produced a surface melting. Again and again the first thousand feet or so of descent have been spoiled because the crust was too hard and slippery. But the lower one ran down the better the ski-ing. The hard marble crust of winter gave way to the perforated or film crust of spring. In April, in the High Alps, winter conditions often prevail at high altitudes to give way to spring conditions lower down. You start a run on marble crust and end on perforated or film crust. The lower the altitude the milder the night frost, and hence the better the crust.
But of course the hard crust of dawn is soon changed under the influence of the sun. At first the sun produces a slight surface softening which is, however, quite sufficient to make a great deal of difference. Even marble crust, if superficially softened, yields excellent running. Gradually the melting process becomes more pronounced. Sun-touched crust with a slight surface moistening--quite sufficient to make Christianias and Stemming turns a joy--yields to crust covered by an inch or two of melted snow. Such crust is known as Telemark crust--not because Christianias are not easy, but because Telemarks are very simple, whereas Telemarks are difficult, if not impossible, on hard crust.
Telemark crust is a normal stage in the passage of hard crust to melted snow. It is the practical certainty of finding Telemark crust at certain hours in spring that makes spring ski-ing in fine weather such a delight.[21]
As the sun increases in strength all trace of the underlying crust disappears. The snow is melted through and through, and becomes dangerous on steep slopes.
This wet snow is often slow, but it never sticks like the wet snow of winter. On steep slopes it gives good running--if unsafe.
Snow sticks in the intermediate stage between freezing and thawing. Thus powder snow which is beginning to thaw sticks abominably, but snow which is melted through and through does not stick. Snow which has once been thoroughly melted and then refrozen will never stick badly again. A surface of wet snow overlying powder will, of course, stick, but melting snow which rests either on hard crust or on the hard ground does not stick. It may be slow, but it does not adhere in sticky lumps to the running surface.
Thus two inches of melted snow on top of crust (Telemark crust) gives a fine running surface, and an inch or even less of wet snow on grass also gives excellent sport.
Snow that has been melted and refrozen night after night soon acquires a crystalline character. When the crust begins to melt after the sun has struck it, the melting surface is composed of numerous wet crystals, sometimes about the size of salt crystals, sometimes much larger.
This granular snow is familiar to all spring runners, and gives an excellent ski-ing surface. Occasionally towards sunset, as the wet heavy snow that is usually found in the afternoon during the wet spring begins to freeze again, you will find the snow assuming a very marked crystalline formation, which resembles the wet hypo crystals with which photographers are familiar.
In general, so long as snow retains a crystalline formation it gives good running. Salt snow or hypo snow yields excellent sport. In May at low altitudes the sun, however, is so powerful that it dissolves the crystals and reduces all the snow to one consistent heavy wet slush. Such snow does not stick--that is to say, it does not adhere to the running surface--but it is very slow. Furthermore it is dangerous, because if you run suddenly on to a patch of this very heavy snow you are liable to be pitched on to your face. Often the snow is not only melted downwards but upwards, for the ground is very warm in spring, and thaws the snow from below, so that you will often find a patch of soft heavy snow resting in the form of a shallow bridge on an empty space. The ski break down the bridge of snow, and the ski-runner pitches heavily forward. Such hollow snow is seldom found in April, but is common in May at lowish altitudes. In May the best ski-ing at low altitudes (5000-7000 feet) is obtained before 10 a.m. and after 7 p.m. In the early morning and just after sunset I have often enjoyed first-class ski-ing right down to 5000 feet and lower, well on into the middle of May.
We may therefore sum up the normal cycle of a spring day as follows:
At dawn every slope will be covered by a hard homogeneous crust. This crust will be either marble crust, in which case it will yield very difficult and unpleasant ski-ing, or perforated crust or film crust. Perforated and film crusts give excellent ski-ing even before the sun has begun to soften the crust.
When the sun begins to gain in strength the hard crust is superficially softened, and gives good running even in the case of marble crust.
A later stage is reached when the hard crust is softened to a depth of about two or three inches (Telemark crust). This again gives good running.
Either before or after midday, according to altitude and inclination, all traces of crust disappear, and all slopes at moderate altitudes are reduced to wet, heavy and more or less water-logged snow. In the early spring this stage is perhaps only reached on southern slopes. In the late spring it is reached on all slopes at low altitudes and on north slopes, save, perhaps, at very high altitudes. In general, the ski-runner should not be abroad at such hours. Towards evening the slopes begin to refreeze. There may be an interval of hypo snow--soft hypo-like crystals in which fast running and every kind of swing is perfectly safe and easy. This is soon followed by the formation of a soft breakable crust, which gradually hardens until at last the cycle is complete by the formation of a hard solid crust.
THUS IN GENERAL THERE ARE TWO PERIODS OF A SPRING DAY WHEN SKI-ING IS EASY, FAST AND SAFE. THE FIRST PERIOD IS WHEN THE HARD CRUST BEGINS TO SOFTEN, AND THE SECOND PERIOD IS WHEN THE WET MELTED SNOW BEGINS TO FREEZE. THE SKI-ING IS LEAST PLEASANT AND MOST DANGEROUS BETWEEN MIDDAY AND SUNSET.
THE EFFECT OF FÖHN AND THAW
So far we have discussed normal winter and spring conditions. Föhn is, unfortunately, associated not only with spring but with winter. The conditions that are produced by Föhn are, however, spring conditions rather than winter conditions; for Föhn, though by no means uncommon in winter, is at least abnormal, whereas periods, more or less prolonged, of Föhn weather may be regarded as normal in spring. The peasants have a saying that, if the Föhn did not blow, the good God and the warm sun could do little with the snow. Certainly but for Föhn Switzerland would still be covered with glaciers.
Föhn, strictly speaking, should be used only for the warm dry wind that blows from the south, and which has been the cause of so many fires. The fire of Grindelwald was caused by this type of Föhn. The wind dries up the wooden chalets, and a spark from a cigar or a kitchen fire, carried on the wind, is enough to kindle wooden buildings from which the wind has absorbed every trace of moisture. But the word Föhn is also used for the warm, damp south-west wind, which is in every way utterly different from dry Föhn. They are alike only in that both dry and wet Föhn raise the temperature and melt the snow.
I propose to call the true Föhn DRY FÖHN and the wet, warm south-west wind WET FÖHN.
Dry Föhn is often associated with long spells of warm dry weather. The skies are cloudless, and there is no hint of rain to be seen. You know that there is Föhn in the air by a peculiar warm dryness, a marked absence of coolness and moisture in the atmosphere.
The wet Föhn always brings rain. Sometimes dry and wet Föhn will fight for the mastery. Sometimes dry Föhn will emerge into wet Föhn and bring down the rain, only to recover its mastery a day or two later.
[Sidenote: Föhn in Winter.]
Let us consider the effect of wet Föhn in winter proper. The ski-runner is bound to detect the first hint of wet Föhn in the air by a slight stickiness in any powder snow that he may chance to be ski-ing on. If the wet Föhn is slight, copious waxing will eliminate its effects; but if it is pronounced, the snow will ball and stick atrociously.
Should the Föhn disappear, it leaves its legacy behind. All slopes of powder snow which have been affected are covered with a crust, which will be more or less thick according as the thaw has been more or less severe. I assume, of course, that the thaw had been followed by the frost at night, without which crust cannot be produced. Only a new snowfall can restore a slope of powder snow which has once been melted by Föhn to its pristine conditions.
Sometimes the Föhn is so slight that the surface of the powder snow is barely touched. It is not covered by crust, but there is a suspicion of resistance as the ski drive through due to an embryo crust. Telemarks are not quite so easy, and a very fast swing is apt to throw the ski-runner outwards, owing to the fact that the side-slip is less pronounced; for the snow gives less easily when covered by the first hint of crust. More usually the Föhn, if it once begins, is accompanied by rain. Often even in December heavy rain will fall on all slopes below 12,000 feet. Directly the Föhn disappears the usual winter frosts will convert such slopes into solid icy crust which is harder and more slippery than any marble crust produced by sun or wind. I have seen crust, formed by Föhn followed by frost, so hard that neither ski nor hobnailed boots left any perceptible trace; and on an easy slope which a beginner could take straight I have slid down helplessly on my back some hundred yards, only to be saved from a further and probably fatal fall by a guide, who thoughtfully received my head in the pit of his stomach, breaking a thumb in the effort to arrest me.
That was an extreme case of ice crust produced by Föhn, but it is not uncommon to find every slope below 10,000 feet covered by an icy crust, on which ski-ing is impossible. The wise ski-runner climbs on crampons, and selects a due south slope for the descent, and times his descent for midday. The slight surface softening produced by the sun is usually enough to produce superficial stickiness, which gives capital running, provided that you have mastered the Stemming turn and Christiania. But, except at or near midday, and except on south slopes, ski-ing is impossible during such periods.
Sometimes good ski-ing is obtained near stream beds when all other slopes are covered by hard crust. The mist that rises from the stream bed descends in hoar frost and covers the crust with a layer of crystals deep enough to take a turn. But such slopes are scarce.
Occasionally the wet Föhn is followed by a period of dry Föhn.
In this case the frost at night is much milder, and you will often find instead of marble or icy crust typical spring formations. I have found perforated crust and even film crust in January, when a period of dry Föhn with high temperatures by day and mild frosts by night had followed two or three days of rain.
For weeks together I have known the crust formed by dry Föhn to resemble perforated crust, but formed of a much smoother and more slippery texture. Imagine a hard surface pitted by numberless smooth little round hollows about the size of half-crown pieces. This type of hard perforated crust gives good running, but calls for a thorough mastery of hard snow turns.
Often the dry Föhn produced a surface-melting to a depth of two or three inches--typical spring conditions in midwinter.
This again is an illustration of the law stated on p. 414: “The milder the frost the better the crust.” In other words, once the snow in midwinter has been thoroughly spoiled by thaw followed by frost, the ski-ing will be best when the conditions approximate as nearly as possible to those characteristic of spring.
Spring snow is quite common in winter when dry Föhn follows wet Föhn, and the wise ski-runner will seize every chance of securing spring conditions once he has despaired of proper winter conditions. He will choose south slopes instead of north slopes, low altitudes instead of high altitudes, and time his descent for the sunny rather than the shady hours. “The milder the frost the better the crust.” From which it follows that the lower the altitude and the drier the Föhn the better the ski-ing--once normal winter conditions have been interrupted.
It is most interesting to observe how the same slope will be composed of typical spring crust one day and of impossible slippery winter marble crust the next day. The difference is solely due to the fact that, in the first case, the night’s frost had been mild, and in the second case severe.
After Föhn you will often, for instance, find a queer kind of surface, called Foam crust, composed of innumerable overlapping edges, miniature cornices formed by a little trickle of water, a mere drop, which has run off a thin small eave of snow. Now hard frozen foam crust is very unpleasant, but directly the dry Föhn gains the mastery, and directly the hard foam crust is exposed to a hot sun and a hot dry Föhn atmosphere, it immediately softens, and yields very fine ski-ing not unlike the best Telemark crust.
To summarize the effect of Föhn in WINTER:
Wet Föhn followed by frosts produces a crust on all slopes which have been exposed to thaw. If the Föhn is very pronounced, and is accompanied by rain, which is followed by frost, all slopes will be covered by a hard solid crust.
If a period of normal cold winter weather sets in, this crust will be very hard and very slippery, and will only yield good ski-ing on south slopes exposed to the sun.
If the wet Föhn is followed by dry Föhn, you will get spring conditions at any rate at low altitudes--a hard crust, smoother but not unlike perforated crust, in the early morning, and a soft crust, not unlike Telemark crust, on south slopes when the sun is shining on them.
[Sidenote: Föhn in Spring.]
The Föhn is less deadly in spring, because snow which has been crusted by Föhn and frost is remelted by the sun, and the sun and frost together will always produce the same surface, whatever has gone before. A wind-swept slope or a Föhn-crusted slope are affected in precisely the same way. In winter Föhn spoils all snow that it has affected, and, save for the lucky accident of dry Föhn, one has to wait for a new fall till normal winter conditions are restored. But in spring, once the Föhn has ceased, a single sunny day followed by a single cold night’s frost is sufficient to produce the normal spring conditions, hard crust in the morning passing through the normal transformations of the spring day.
Wet Föhn is, however, most unpleasant in spring while it lasts. If you are caught by wet Föhn in a club hut you are imprisoned till the Föhn passes, for the wet Föhn brings down the avalanches on every slope above 23 degrees (see p. 430). Ski-ing, while there is a touch of wet Föhn in the air, is always unpleasant. Snow which has been melted by the sun in a dry atmosphere never entirely loses its crystalline formation, excepting at low altitudes in the very late spring. And even then sun-melted snow is never so unpleasant as snow melted by the Föhn. The Föhn disintegrates the snow, destroys the crystalline formation, reduces the snow to one uniform heavy mass.
Such snow does not stick in spring, provided it has been through the usual process of melting and refreezing on previous days. But though the spring Föhn does not produce stickiness, it gives the snow a dragging, clogging grip. It may not ‘ball’ under the ski like sticky snow in winter, but on all but steep slopes it makes ski-ing desperately slow. Uphill work is most trying, for the friction between wet Föhn snow and the ski is very marked. The ski have to be thrust through the clinging surface, and the wet Föhn not only affects the snow, it affects one’s whole body and produces a general sense of lassitude.
SUMMER SNOW
Between July and the end of September the snowline climbs ever higher. The snow above this snowline obeys the laws that we have tried to explain in the preceding pages. Snow is transformed into crust by the action of sun or thaw or wind, and the crust itself affords good or bad ski-ing, according to the conditions under which it has been produced and the conditions that affect it when once it has been formed.
In the summer you will meet with every type of snow in the High Alps. After a fresh snowfall the snow will often remain powdery for days on northern slopes at great altitudes. Between July and the beginning of the winter you will find typical winter snow, powder snow or wind-driven snow: you will find typical spring snow, such as film crust or perforated crust, but you will not find any type of snow which can fairly be described as mainly characteristic of the summer. The conditions in July and the first half of August will approximate to those of June, though of course there will be far less snow in August than in June. Towards the end of September the snow conditions will approximate to those of the winter proper, with the important difference that the snow at the end of September approaches a minimum.
Once the ski are left behind and the final climb begun on foot, there will be many complex and difficult problems of snow craft to solve which, however, hardly come within the scope of pure ski-ing. Of these the most important is the problem of safety. Once the ski are left behind, the climber’s interest in the snow is reduced to two main problems: Is the snow hard enough to make going easy and yet not so hard as to need step-cutting? Is the snow safe or will it avalanche?
The avalanche question will be treated in its proper place. Summer Ski-ing will be dealt with on pp. 468-470.
I have tried to condense this section, and, like all condensed and theoretic writing, it will no doubt prove rather dull reading. In the later sections I shall try to provide concrete illustrations of the principles here explained, and to show how the laws of snow craft may be applied in order to get good ski-ing in the months of the alpine calendar.
SNOW AVALANCHES
Snow avalanches may be classified either as Ground avalanches or as Superficial avalanches.
GROUND AVALANCHES--the ‘Grundlawinen’ of Continental writers--may be defined as avalanches in which the entire snow surface is stripped off a slope, revealing the underlying earth, grass or rock.
SUPERFICIAL AVALANCHES may be defined as avalanches in which a layer of snow, more or less deep, slides off an underlying layer of snow or ice.
Before proceeding to discuss avalanches in general, and to analyse more exactly the various subdivisions of these two principal categories, it is essential to analyse the primary conditions that produce avalanches. Primary conditions may be defined as those which exist before the snow has covered a slope, originally bare of snow. These primary conditions are the contour and gradient of the slope and the nature of the surface that underlies the snow.
No avalanche has yet been observed on slopes whose gradient is less than 23 degrees, though, of course, even level slopes have often been overwhelmed by avalanches falling from steep slopes above.
Other things being equal, the stability of a snow slope depends not only on its gradient, but also on the gradient of the slopes just below and the slopes just above.
A concave slope, for instance, which has an even outflow so that there is no sudden change of gradient and so that the steeper slopes merge gradually into gentle slopes and these gentle slopes into a level outrun, is infinitely safer than a convex slope the higher portions of which are more gradual than the lower portions below. Slopes that steepen suddenly below a comparatively safe gradient should always be treated with great respect.
A slope, whose gradient would be perfectly safe if the slope petered out gradually, may be highly dangerous if the gentler slope ends suddenly in a steep slope, for the snow on the gentle slope is, so to speak, ‘in the air.’ It has lost the natural support which is afforded by a gradual concave base leading out on to the level, and there is a reasonable chance of the weight of the snow on the safer slope proving just too much to stand the strain at the point where the slope steepens. In general concave slopes are safer than convex slopes, and slopes where the gradient steadily diminishes towards the base are safer than those in which the gradient increases before the base is reached. Of course, any slope overhanging a cliff is always to be treated with very great care, as even a superficial snow slide which would be quite innocuous if the slope ended on easy safe ground may prove fatal if it carries the ski-runner to the edge of a cliff below.
The chance of surviving an avalanche depends greatly on the nature of the ground where the avalanche comes to rest. Many ski-runners have escaped unhurt after being carried down several hundred feet because they have managed to keep on the surface of the avalanche and because the avalanche has gradually spread out fan-shaped on open, gentle slopes. But an avalanche falling into the bed of a narrow V-shaped valley with steep sides is almost certain to prove fatal, for the victim of this avalanche will be buried by the snow falling above, and this snow will fill up the narrow bed of the valley and freeze solid instantaneously by pressure. Thus all narrow valleys such as the Urbachthal, or the upper Rhone valley between Gletsch and Oberwald, should only be ascended when the snow is thoroughly safe.
An analogous case is where a tributary ridge runs across a hillside. An avalanche falling down this hillside will pile itself up against the tributary ridge and a ski-runner will probably be crushed below the avalanche, squeezed in between the tributary ridge and the main slope. Often a large moraine fulfils these conditions, so that an avalanche falling from a neighbouring slope is arrested at the moraine and piled up against it.
Similarly, if you are caught by an avalanche while ascending a gully, your chance of escape is much greater if the gully widens below the point where the avalanche overwhelms you. If it contracts, the pressure of the snow forcing its way through a narrow space may crush you to death. Compare the account of the avalanche that killed Bennen quoted in Scrambles in the Alps.
The bottom of a valley is not only dangerous for reasons just stated, but also because the stream at the bottom of a valley often exercises, especially in spring, an undercutting effect on the snow slopes that end in the stream bed.
The nature of the underlying surface, apart from its contour and gradient, is a factor of vital importance, especially in the early winter and in the spring. At intervening periods most avalanches are superficial, and slide from an underlying surface of hard snow; but in the early winter and in the late spring the whole snow slope slides away, so that the nature of the underlying surface and the probable support that it affords is of great importance.
Steep grass-slopes form a dangerous under-surface, especially where it is never or seldom mown; for long unmown grass generally lies facing downwards, and offers a most slippery surface.
Grass which is regularly mown is usually short and stubby in winter, and gives better purchase to the snow. A slope covered by stony boulders, bushes or trees is usually fairly safe, though a big avalanche, once it is fairly under weigh, will sweep over shrubs and even over small trees. Fairly dense wood may usually be considered as safe, provided one avoids the long open clearings made by old avalanches, which so often run down the middle of a forest.
An elementary knowledge of geology is useful; the excellent geological maps published by the Swiss Survey can often be consulted with benefit. Rocks which suffer much surface disintegration provide a better purchase for snow than very hard and consequently very smooth rocks. The hard ‘Hochgebirgskalk,’ an alpine variety of limestone, which is very common, especially in high regions, is slippery, and instead of disintegrating gradually, as gneiss or granite disintegrates, has a habit of breaking away along vertical and horizontal joints.
The common rock known as ‘Flysch,’ common in the lower Alps, provides a much safer surface.
Glacier-polished rocks are, of course, especially dangerous, and the whole Grimsel region is consequently swept by avalanches throughout the winter.
The lie of the strata is an important factor. Where, as is usually the case, the strata are inclined, one slope of a mountain will usually be safer than the other. Diagrams I and II represent the north and south slopes of a ridge running more or less east and west. The ridge is formed by parallel but inclined bands of strata. Rock climbers know that the slope in Diagram I, though of the same gradient as the slope in Diagram II, is very much more difficult to climb. It is also much more liable to avalanche, as the outcrop of the strata provide a natural check to avalanches in Diagram II; whereas in Diagram I each outcrop forms a small steep snow slope quite unsupported. If the outcrops are of reasonable breadth, there will be belts running across the face of the slope at A’, B’, C’, D’ which will be inclined into the slope, and provide a safe line of traverse; whereas there is no safe line for a ski-runner desiring to traverse or ascend the slope A, B, C, D.
Geological maps indicate the ‘strike’ of the strata, and therefore provide useful clues as to the varying liability of slopes to avalanche.
Loose scree guarantees the ski-runner against ground avalanches, but, as the winter advances, loose scree is soon covered with deep snow, from which later layers of snow can slide uninfluenced by the underlying scree. In fact, as the winter advances, the original underlying surface plays a smaller part in the problem of avalanches. Hard-crusted snow covered by soft snow is especially dangerous, and of course ice, as is so often met with in the High Alps, is the worst under-surface of all. Fortunately, snow often attaches itself firmly to ice, transforming an ice slope into a snow slope.
The conditions necessary for this transformation will be explained on pp. 426-427.
So far we have dealt with primary conditions, the nature of the ground before the snow has begun to fall and the gradient of the slope from which the avalanche slides. An important factor is the quantity of snow on the slope. It often happens that a shallow superficial layer detaches itself and carries a ski-runner down the slope. If the slope ends on gentle ground, no damage is done beyond the loss of height and the consequent waste of time and effort in reascending to the spot from which the avalanche started. But if the snow slide carries the ski-runner over a cliff or into a bergschrund or crevasse, it is clearly immaterial to the ski-runner whether his original snow slide was 1 inch or 6 feet in thickness.
I propose to use the word SNOW SLIDE for such small avalanches as are only dangerous where they carry the ski-runner on to dangerous ground, such as the edge of a precipice, and to reserve the word AVALANCHE for avalanches deep enough in themselves to overwhelm and possibly to kill a ski-runner.
Though a very small layer of snow--an inch or even less--is enough to produce a snow slide, especially if the shallow layer rests on ice, the amount of snow necessary to produce a real avalanche is much greater, and varies very much with the quality of the snow.
CLASSIFICATION OF AVALANCHES
The old writers divided avalanches into ‘Grundlawinen’ (ground avalanches) and ‘Staublawinen’ (dust avalanches)--a misleading classification, for a ground avalanche may be composed of dry powder snow, and produce all the appearance of a ‘Staublawinen’: the clouds of white snow dust, once supposed to be peculiar to avalanches of powder snow, are really common in almost every type of big avalanche, especially where the avalanche falls over steep cliffs. I prefer to divide snow avalanches into four main classes:
I. Dry powder avalanches.
II. Wet new snow avalanches (i.e. powder snow which has begun to thaw as differentiated from old wet snow which is formed by crust which has been thoroughly melted).
III. Snow-slabs.
IV. Wet old snow avalanches--the Grundlawinen of the older authors.
I. DRY POWDER AVALANCHES.--Newly fallen snow, which has not been subject to thaw or sun, contains a great deal of air until it settles, and even when it has settled it still imprisons a considerable quantity of air. This makes for stability, for snow is less likely to avalanche when it lacks cohesion. I have often experimented on newly fallen snow at a low temperature, and I have found it almost impossible to start an avalanche on any slope below about 35 degrees and less than about 200 feet in height. Small snow slides are common enough if the underlying surface is hard; but as a rule even snow slides come to a standstill after a few yards. The really dangerous dry powder avalanches only occur on very long and steep slopes, where the amount and mass of the snow is sufficient to produce the necessary momentum for a big avalanche. Dry powder has a strong internal friction, and, as a rule, some powerful external impact is necessary to start an avalanche. Of such impacts wind is the most dangerous. A sudden blizzard may convert a valley, safe when the ski-runner entered it, into a veritable death-trap. Further, the fall of an avalanche on one side of a valley may precipitate other avalanches on the opposite side. Partly owing to the air imprisoned in dry powder, and partly owing to the momentum of the avalanche itself, the wind caused by a big fall of snow is extremely powerful and destructive. Houses and trees are torn away by the blast, even though they may be beyond the track of the avalanche. The force of the wind is multiplied manifold when the avalanche falls into a constricted space, such as the floor of a narrow valley. I have seen a bridge just below Gletsch destroyed by a spring avalanche, or rather by the wind caused by an avalanche on the opposite side of this very narrow valley. A large part of the bridge, weighing several tons, had been thrown upwards to a height of about 150 feet!
After a heavy snowfall the danger of dry powder avalanches may last for a day or two, or even more; but as a rule two or three days of settled weather and keen frosts render most northern slopes--in winter, though not in spring--safe enough. When the powder snow has passed into the stage known as Crystal powder--i.e. when the small light dry powder has been converted into crystals of an appreciable size--the danger of avalanches is very remote. On a windless day with a temperature in the shade below freezing, I should not hesitate to cross almost any slope up to 35 degrees which was covered by genuine crystal powder snow, provided that the slope petered out gradually on to the level and did not overhang a cliff.
II. WET NEW SNOW AVALANCHES.--Directly the powder snow is exposed to surface thaw, either owing to a rise of temperature or to the sun, its weight and cohesiveness increase, and the danger of avalanches is consequently much greater. Sometimes the snow falls with a temperature above freezing. This wet new snow is dangerous, but as it is also extremely unpleasant for ski-ing, few ski-runners are likely to be abroad. On the other hand, ski-runners are often tempted to cross a southern slope where the powder is beginning to melt. Snow on a steep southern slope soon gets thawed through the bottom, so that ground avalanches are quite normal in winter on south slopes. As a rule, south slopes in winter get rid of their superfluous snow in the first two or three days of fine weather. The snow that remains is thawed by day and frozen by night, so that at the end of four or five days the south slopes have got rid of their avalanches, and the snow that remains is a crust more or less hard and slippery. This crust by day may become soft breakable crust, but once it has crusted, a slope in the winter is not likely to avalanche until there is a new snowfall. A very marked rise in temperature may make a south slope that has been crusted dangerous again; but such sudden and marked rises of temperature are rare in winter.
In general, therefore, south slopes in winter are safer than north slopes. They give rise to more avalanches, but such avalanches as fall off south slopes generally fall within two or three days after a snowfall, after which a south slope is crusted and safe in winter; and though after a few days of settled weather most north slopes are absolutely safe, very steep and very long north slopes, or short steep slopes overhanging a cliff, are always dangerous. Of course, whenever the wet Föhn is blowing, or whenever there is a general thaw, all steep slopes, and a great many moderate slopes, become very dangerous indeed. The effect of the thaw is to give the snow the cohesiveness and weight which it lacks in its pristine dry condition. The dampness in the air saturates the snow with moisture and increases its weight. During a severe Föhn you will often see huge ground avalanches almost as destructive as those that fall in spring. When the Föhn is blowing ski-ing is always extremely dangerous. Fortunately, it is also extremely unpleasant, or fatal avalanche accidents would be more frequent.
The dry Föhn (see p. 418) is much less dangerous. Unless it is very pronounced, it will hardly affect northern slopes in winter, though it may convert a south slope, usually covered by hard crust, and therefore safe, into soft wet and dangerous snow.
In spring northern slopes usually hold powder snow for a few days at high altitudes, and even at moderate altitudes in the early spring, such as March. This powder snow soon loses the dry, light, powdery characteristics of winter powder. Though it continues to yield excellent running, spring powder is very liable to avalanche. It is damper and more cohesive than dry powder, and therefore more dangerous. Dry powder often rests on the ground below. A northern slope will often be covered with a homogeneous layer of powder some feet in depth, but spring powder (see p. 413) invariably rests on a hard-crusted slope below. It therefore tends to slide away during the warm hours of the day, and should be treated with very great caution.
Avalanches composed of spring powder are, properly speaking, new wet snow avalanches. They must be carefully distinguished from old wet snow avalanches, for old wet snow is formed by the melting of crust, whereas spring powder is formed by the melting of powder snow, i.e. ‘new snow.’ Snow may be defined as ‘new’ before it has been crusted, and as ‘old’ when it has been through the crusting process. Thus powder snow is always ‘new,’ however long it may be since it fell. On the other hand, a snowfall in June may be turned into crust within twenty-four hours, and thereby become ‘old snow.’ Crust and soft snow formed by the melting of crust are both ‘old’ snow.
Spring powder is all the more dangerous, because it yields wonderful ski-ing at a time when other slopes have been spoiled by the sun. Furthermore, as spring powder is found on north slopes, ignorant ski-runners underestimate its danger; for it is a common fallacy among the inexperienced that south slopes are more dangerous than north. In spring the reverse is usually the case, for avalanches in spring are occasioned by the general air temperature just as much as by the sun. (See also below, p. 438)
III. THE WIND-SLAB.--The wind-slab is the most treacherous of all avalanches, the most difficult to foresee, and the most incalculable in effect.
Falling snow is usually accompanied in the High Alps, and often accompanied in the lower regions, by wind. If the wind is powerful, the falling snow is driven over exposed ridges in whirlwinds, and comes to rest on the lee-side and in sheltered hollows. In this way the snowy avenues leading to glacier passes and the more sheltered snow-fields receive more than a fair share of snow. This action of the wind, denuding the exposed ridges and feeding the hollows and lee-sides, takes place on both a large and a small scale: on a large scale, when snowy valleys are fed from the snow blown off the exposed ridges that rise out of them, and on a small scale on any slope exposed to wind which is divided by ridges, however small. Any tributary ridge on a slope across which a wind is blowing will have a wind-side and a lee-side, and will accumulate snow on the lee-side and give off snow on the wind-side. A stone wall or even a hedge provides an example of this on a small scale.
Snow driven by wind and settled on lee-sides may either be more or less powdery, a denser, heavier powder than normal powder, or it may assume one of the many forms of wind-caused crust. We have described on p. 407 the various forms of winded powder, such as ripplemark, caked powder, etc., and on p. 408 the various forms of wind-formed crust, such as windboard and Skavla.
In general, the greatest caution should be exercised when crossing any slope which has accumulated much wind-driven snow. Wind-driven powder snow is heavier and more adhesive than ordinary powder. It is more detached from the underlying surface, and is much more conducive to avalanches. The ski-runner should keep his eyes open for traces of wind action, and when he finds snow which has obviously been exposed to severe wind, he should exercise the greatest possible caution on crossing over to the lee-side of a ridge dividing slopes, whence the snow has obviously been blown away, from slopes where the wind-driven snow may have fallen back to earth. Wind-driven powder may in turn be covered by a new snowfall, which adds to the difficulties of diagnosing the avalanche risk.
So far we have been dealing with wind-driven snow which still retains some suggestion of powder, which is soft and dense and caky. A still more treacherous and dangerous wind formation is the wind-slab, or ‘Schneebrett,’ of Continental authors.
Windboard, as already explained (p. 407), is a hard, slippery crust formed by wind. Windboard is common on glaciers in the winter months, and though disagreeable to ski on, it is safe enough in most cases. Sometimes, however, this windboard, instead of being homogeneous with the underlying snow, is loosely attached, and in places forms a vault with a hollow space between the windboard and the snow beneath. The windboard is, then, properly speaking, a wind-slab. The wind-slab, or, as some writers prefer to call it, the snow-slab, is formed by wind-driven snow, which eventually settles into a hard crust. As the wind-drifted snow is of a different density to the snow on which it settles, it tends to form a distinct stratum from the underlying snow. In winter the temperature is usually considerably below freezing, so that snow which falls, or snow which is drifted by the wind, cannot bind with the snow below. In order for two strata of snow of very different density to form a homogeneous whole, there must be a period when the temperature is just above freezing in order to produce the melting followed by frost, which is a necessary factor in the fusing together of two successive layers of different types of snow.
The wind-drifted snow, ultimately transformed into a hard crust, is then of a different density to the snow below, to which it is loosely attached. This underlying snow may be either soft snow or hard crust; in either case the wind-slab forms a covering layer insecurely attached to the foundation snow. This superficial layer is subject to different strains from those which affect the underlying snow; for the tension due to the expansion and contraction which follows changes of temperature affects the layers formed of snows of different density and character in varying ways. The surface layer, or wind-slab, may contract more obviously than the snow below, so that if the slope is concave in shape, the wind-slab, in contracting, tends to form an arch above a more or less shallow vault.
There is little if any surface indication to betray the fact that the wind-slab is not homogeneous with the underlying snow; the ski-runner may cross some such slope without the least suspicion that the hard, slippery crust is not quite so solid as it appears. Suddenly he will hear a sharp cracking noise; the hard crust will settle under him and cave in; the crust cracks along the line made by his ski, and the whole slope comes down on top of him in a cataract of tumbling blocks. The strata formed by the wind comes away, tearing with it much of the soft underlying snow, and pours down in a floor of hard, icy blocks of snow.
The wind-slab is the most dangerous and deceptive form of avalanche. Its hard polished surface gives a false sense of security. The temperature is no guide, for wind-slabs can avalanche at any temperature. Indeed, extreme frost tends to make the wind-slab more brittle. It can avalanche after days or weeks of fine weather when all the more obvious avalanches have fallen. Lastly, this wind-slab is to be found in the natural line of approach to glacier passes, in the long sheltered avenues that collect the snow blown off the exposed ridges.
It is of primary importance to distinguish most carefully between the crust formed by sun action and the crust formed by wind. A south slope crusted by sun followed by frost will never avalanche so long as the crust remains unmelted. Sun-formed crusts never avalanche. A careful study of south slopes will soon teach the ski-runner to recognize crust formed by sun and to distinguish it from crust formed by wind. The wind-slab is usually patchy, granulated, and often betrays the action of wind by a slight rippled appearance. The expert can detect wind-formed crust and can distinguish it from sun-formed crust.
The contrast between crust formed by sun (or by any process of alternate melting and frost) and crust formed by wind is instructive. The fact that the former is safe and the latter often dangerous is due not to any surface differences but to the difference in the nature of the connection between the under-surface of the crust and the underlying snow.
Sun-formed crust always merges gradually into the underlying snow. There is no sharp plane of cleavage. The hard crust merges into softer crust; the softer crust into soft snow. There is often, of course, a plane of cleavage between two successive falls of snow--the upper layer may be soft snow resting on crust; or it may be snow which is superficially crusted resting on crust. And directly the sun melts the superficial crust there may be danger. But so long as crust formed by alternate melting and frost remains unsoftened by the sun, it may be deemed to be absolutely safe so far as avalanches are concerned, for this sun-formed crust will merge gradually into the snow immediately below it.
Wind-formed crust is, however, often sharply separated from the snow underneath it. Wind-swept crust may overlie powder snow with no intervening and softer crust to act as a binding influence. The crust may be absolutely separate, susceptible to different strains and tensions, and forming the shallow vault described above.
Should you suspect a wind-slab, sound with the ice-axe, and try to discover whether the snow is homogeneous or rests on a soft streak of snow below. If, at the border of the dangerous slope, a sharp stamping with your ski produces a settling noise, followed by the breaking away of detached fragments of snow-slab, you will know that the slab is probably insecurely poised on a shallow vault below.
Wind-slabs are, fortunately, not very common. They can only exist under winter conditions, heavy snowfalls, severe wind and comparatively weak sun action. After April, for instance, the formation of a wind-slab would be impossible, for the May sun is strong enough to melt any crust formed by wind or by any other action. In summer they are uncommon excepting under unusual conditions. They sometimes occur in late summer, when the sun has lost much of its strength and is no longer powerful enough to thaw snow which has been converted by wind into a wind-slab.
IV. OLD WET SNOW AVALANCHES.--For the distinction between old wet snow and new wet snow, see p. 427.
Old wet snow avalanches are very common in spring. The snow, which has been melted and frozen, and remelted again and again, gradually becomes denser and heavier. As the spring advances the power of the sun becomes very great. In the afternoon, and at lower altitudes long before midday, most snow slopes are saturated to a greater or a lesser depth by the melting power of the sun. Such old wet snow is of course extremely dangerous.
The great spring avalanches, the ‘Grundlawinen’ of Continental writers, usually select well-known tracks. Some of them have local names, and their annual occurrence is as regular as the return of spring. The long tongues of bare spaces between forests mark their track. Incredible quantities of snow are torn from the mountain side; trees are uprooted and boulders carried downwards. The avalanche comes to rest far below, and spreads out a discoloured tongue of snow-blocks, dark with the earth rooted from the mountain side, and strewn with small trees and shrubs. Sometimes, after an unusually severe winter, these big spring avalanches extend their domain, and destroy chalets, and bridges, and even villages. Roads that cross the line of these spring avalanches must be ensured against destruction by tunnels.
Superficial avalanches of old wet snow are more common than these big ground avalanches. These superficial avalanches occur daily in spring weather. The snow is saturated with water, which acts as a lubricant between one layer of snow and the harder crust beneath. Sometimes avalanches are started by the snow thawing from the ground upwards, for the ground in the late spring is warm enough to thaw the snow immediately above it. I have seen a vault one foot in height between the ground and the overlying snow.
The power of avalanches is best appreciated by those who have visited the Alps in May. It is an interesting, if annoying, experience to be confined to some high alpine club hut in May by a sudden invasion of Föhn. If the club hut can only be approached over steep ground or up a steep and narrow valley, there is nothing to be done but to wait till the Föhn disappears. Hardly a minute passes without an avalanche falling off some near or distant slope. The roar of big avalanches is varied by the hiss of the smaller snow-slides. Thousands of tons of snow are removed from the steeper slopes every hour.
Old wet snow avalanches are much more deadly than avalanches formed of new snow. Newly fallen snow weighs about 1½ cwt. the cubic yard. Old wet spring snow weighs about 15 cwt. or ¾ of a ton the cubic yard--in other words, ten times as much as newly fallen snow.
Furthermore, if you are overwhelmed by old wet snow, you will find the very greatest difficulty in freeing yourself, even if you are only covered by a layer a foot or so in depth. Powder snow contains a great deal of air, so that you can live for some time even if buried in a powder avalanche, but the wet spring snow contains nothing but water, and suffocation is a matter of minutes.
Whenever the Föhn blows in spring, all slopes above a very moderate degree of steepness immediately become extremely dangerous. In normal clear weather there is a frost at night, so that any slope, however steep, can be crossed without fear of avalanches between sunset and dawn. As soon as the superficial soft crust begins to form on the wet snow all danger of avalanches disappears.
On the lower slopes in May, the interval after the dawn during which a steep slope may be crossed with safety varies greatly. In May hard crust softens with surprising speed, and after 9 a.m., or even earlier, the risk of avalanches below the glacier level soon becomes formidable.
A vital distinction must be drawn between the kind of softening that is produced when a solid homogeneous crust softens superficially, and the melting of a superficial layer or crust resting on an older crust below. The second case occurs when a layer of soft snow, or of crust, rests on the older strata of crust. Once this new layer has melted it is very liable to slide off from the older layer below. On the other hand, a homogeneous crust softening superficially is usually safe enough so long as the underlying crust remains hard. Telemark crust, which is crust softened superficially so that Telemarks are easy (p. 415), is usually safe.
The great danger is the existence of a layer of crust formed by a recent snowfall resting on an older layer. I was once climbing the steep slopes that lead from Zinal to the Mountet glacier. It was on the last day of April, and the sun had just struck the slope. The local guide was leading, and I ventured to suggest a detour to avoid a traverse across a slope that had begun to soften. He ignored the risk, and proceeded. I remained behind and watched him. Suddenly a layer of snow about six inches in thickness, which had softened down to the old hard crust beneath, slid away with startling rapidity. The guide gave a small jump, and got his ski into the old layer, while the softened snow slid away and disappeared over the cliff below. The guide’s top ski had cut through to the old layer before the snow slipped, otherwise he would have been killed.
In May in the High Alps the risks of such avalanches is small on all save very steep slopes. Most of the big spring avalanches fall below the limits of the summer snowline. They slide off slopes which are bare of snow in summer. Once the region of the névés is reached the danger is very much less, though of course by no means non-existent, especially when the Föhn is blowing. The May ski-runner must often time his ascent to a club hut to arrive in the early hours of the morning, and wait for his descent from the glaciers to the lower valleys for the hour after sunset.
As the winter advances the danger from avalanches increases, not only because the quantity of snow increases and because the sun is more powerful and the temperature higher, but also because the inequalities on the underlying surface gradually disappear. Scree, small boulders, shrubs and other natural checks to the flow of an avalanche vanish in the ever-deepening snow. Roads and small shelving plateaus, which break up a steep slope, get buried. Each succeeding avalanche leaves some of its burden on all protruding shelves, and thereby tends to smooth out the mountain side, creating, in place of a slope broken by inequalities, one long, even flow which presents no hindrance to the avalanche. Thus big avalanches tend to take the place of the smaller avalanches which fell down part of the slope, only to be arrested at some convenient terrace, such as a road or small plateau.
In the spring avalanches often fall right across rivers, which very soon form a tunnel beneath the snow-bridge of the avalanche. Such snow-bridges should be crossed with caution. More than one ski-runner has been killed by breaking through the remains of an avalanche into a river.
It is a common illusion among the inexperienced that north slopes are safer than south slopes in spring. They are not--in fact, north slopes are more dangerous than south slopes. In spring it is the general air temperature which determines the fall of avalanches. True, the south slopes avalanche first, and for this reason north slopes hold much more snow, so that when they finally get rid of their superfluous snow they produce far and away the most destructive avalanches. Of course in spring the sun shines on all slopes, and it shines with quite sufficient force even on due north slopes to produce an avalanche. In fact, the really great spring avalanches are those which fall from northerly slopes.
SUMMER SNOW AVALANCHES
During the summer months, as already explained, every type of snow can be found in the High Alps from pure winter powder to the numberless varieties of spring crusts and spring soft snow.
It follows that avalanches in summer obey the same laws as in spring. There are far fewer avalanches in summer than in spring, for there is far less snow to fall. Quite enough, however, is left to make the avalanche problem of vital importance for the ski-runner and the summer climber.
The various types of avalanches described in this chapter are not confined to winter or spring, with the possible exception of the wind-slab avalanche. I should have said, a priori, that wind-slab avalanches were peculiar to winter and the early spring, for they depend for their existence on snow falling at a very low temperature, and on the snowfall being followed by strong and cold winds before the sun has time to melt the snow and to bind it into the underlying surface. I am told by Mr. Young that he has seen wind-slab avalanches in summer--probably, I should imagine, in the very late summer or early autumn, when the conditions begin to approximate to winter conditions. Apart, then, from wind-slab avalanches, which must be very uncommon in summer, all the other types are by no means unusual. Avalanches of powder snow, of old wet snow and new wet snow can occur at any month of the year.
It is not necessary to give separate rules for summer and for spring. The important factors in the problem are not so much the season as the amount of snow that has fallen, the temperature, the angle of the sun, etc. etc. If the reader thoroughly understands avalanche craft in winter and in spring, he should be able to cope with the same or with similar problems in summer.
The majority of fatal avalanche accidents in summer are due to snow slides. I have for convenience’ sake adopted the arbitrary distinction of avalanches into avalanches proper--those which are dangerous owing to the weight and quantity of the snow that falls--and snow-slides, which are only dangerous in so far as they carry the climber or ski-runner with them over a cliff or into a crevasse. Most summer avalanche accidents are due to snow slides, and occur in places which the ski-runner could not reach on ski. Snow resting on ice in gullies, or snow resting on smooth slabs, etc., are frequent causes of fatal accidents. Such avalanches or snow-slides have been described by Mr. Young.
The classical device for testing whether snow is resting on ice--i.e. throwing a big rock down the suspicious slope--is often of use to a ski-runner who is in doubt whether to descend a doubtful slope on ski or on foot.
TACTICS ON AVALANCHE GROUND
The simplest rule is to avoid avalanche ground. Unfortunately, this is not always possible. The limits of danger are so wide that one may occasionally find oneself on a slope which might conceivably avalanche. Such a slope may provide the only possible means of getting down to the valley, so that the choice is not merely between giving up an expedition or risking an avalanche, but between the certainty of a night out if one recrosses the pass and the possibility of an avalanche.
It has sometimes been asserted that a ski-runner could escape an avalanche by turning his ski downhill and making a sudden dive downward. Of course this is wildly absurd. I have only once been caught in an avalanche, and, long before I could have turned my ski downhill, the avalanche had carried me some twenty yards downhill. An avalanche does not start by a kind of snowball action. It starts with a sharp crack, and the sudden sliding away of a deep layer of snow. Watch snow sliding off a roof and you will understand that an avalanche is very sudden and overwhelming. Almost every avalanche leaves a clean line of cleavage behind--a wall of snow which is exactly as deep as the avalanche at its birth.
The chance of escaping an avalanche by flight is infinitesimal if you are near the point where the avalanche starts. You are lucky if you have time enough to kick your ski off, and you will only be able to do this if you have unloosened the bindings previous to crossing the dangerous slope. There will be no chance of unstrapping them once the avalanche is upon you. If you cannot kick them off instantaneously, they will remain attached to you.
Your chance of surviving is very much greater if you can get rid of your ski, for the ski drag you under, and prevent all hope of fighting your way to the surface of the avalanche. Once you are overwhelmed you should adopt a swimming motion. Above all, try to keep your head uppermost. A vigorous swimming motion with the hands is said to be useful by people who have survived.
Dangerous slopes should always be crossed as high as possible. An avalanche is much more dangerous if it overwhelms you from above than if it starts from the immediate neighbourhood of your ski. Steep slopes below a cliff usually yield a fairly safe passage just below the rocks, for there is often a little gap between the edge of the snow and the rocks which affords a secure route. Take advantage of every belt or shelf of gentler ground that may run across a steep slope. Traces of old roads or even of footpaths are better than nothing.
Clearly a man on ski is much more likely to start an avalanche than a man on foot. I have often been surprised to see chamois-tracks down slopes 40-50 degrees steep. It is true chamois occasionally get killed by avalanches, but they certainly possess a great immunity. The reason is obvious. The chamois’ slender hoofs sink in very deeply. They penetrate right through the snow to any hard underlying crust that there may be beneath. Further, the chamois does not, like the ski-runner, cut the snow by a continuous line which divides the slope in two, and deprives the snow above the ski-tracks of much of its support. Chamois-tracks form a row of small holes, and therefore have a much less unsettling effect.
A man on foot has some of the advantages of the chamois. He is at least much safer than on ski. His feet get down to the old crust below unless the soft snow is very deep. On ski it is extremely easy to start a small superficial avalanche or snow-slide; and on ski it is very difficult to check such a small or big avalanche once it is started. The ski may sink just into the superficial layer and help to detach it.
On dangerous ground you should therefore remove the ski and proceed on foot. If possible, tackle such slopes by a direct ascent or descent in single file. Traversing is much more likely to cut the snow slope and start an avalanche.
Never rope on avalanche ground unless one member of the party can remain on safe ground, i.e. a cluster of rocks, and secure the man who is traversing a short stretch of dangerous snow. If two or three ski-runners are caught by an avalanche while roped together, their chance of escape is slight, as the rope tends to get caught, to drag them under the snow and to suffocate them.
Dangerous ground should, of course, be crossed by only one man at a time.
It has been suggested by an experienced mountaineer that each member of the party should drag behind him a long thin red cord, which would provide a clue to the whereabouts of a man who had been buried by an avalanche. The ski-ing mountaineer’s kit is already so overcharged that few people would be likely to add to it for this purpose.
For the descent of dangerous slopes, if the party do not proceed on foot, they should put on their sealskins, so as to run the slopes as steeply and directly as possible.
The ice-axe should always be driven in as far as possible, so as to find purchase in the underlying snow. Ski-sticks that are provided with removable disks are very useful, as they can be driven in much deeper than ordinary ski-sticks.
When in doubt, sound with an axe or stick and try to discover whether the snow is homogeneous, and if not, what lies below the surface layer and what lies below the snow itself.
When in doubt, turn back if possible. If it is necessary to proceed, take off your ski. If speed is important, keep on your ski; and if you are descending, put on sealskins. If you cannot spare the time to put on sealskins, sit on your ski and descend by a sitting ski-glissade, which is, by the way, a knack in itself.
THE HIGH ALPS IN WINTER
[Sidenote: Weather Conditions.]
The weather after the New Year is usually more settled than in the summer. A spell of absolutely unbroken weather lasting from three weeks to a month or more is almost inevitable some time in January or February. As a rule, February is the finest month in the winter.
These typical fine-weather periods are often accompanied by mild weather. The temperature even by night is often surprisingly high on the glaciers, even when there is no touch of Föhn in the air. This has led some observers to claim that the temperature in winter--even in the shade--is often lower in the valleys than on the mountains. I have never seen any evidence produced for the phenomenon which has been romantically described as ‘inverted temperature,’ and have no reason to believe that any such violation of the laws of temperature really exists. It is often, of course, colder in the plains when the plains are covered by nebelmeer than in sunny alpine stations, but this is very different to any general inversion of temperature. I have, it is true, sat on the summit of the Finsteraarhorn in midwinter stripped to the waist, and I have often been uncomfortably hot at great altitudes in the sun. But it is dangerous to generalize from such experiences, and though on a windless day, winter mountaineering may be as warm and comfortable as summer climbing, the ski-runner must always be prepared for sudden danger of temperature, and severe cold.
The variations in temperature are surprising. A cushion of cold air, several degrees below freezing, may exist near the surface of the snow, and three feet above the surface of the snow the air may be quite mild. This is a phenomenon well known to rink-makers. In the sun the heat may be quite intense, and yet, a few yards off, in the shade the temperature may be several degrees below freezing.
A suspicion of wind may transform a mild and equable into an unpleasantly cold atmosphere. The changes of temperature are very sudden. You may be basking in shirt-sleeves on one side of a ridge, and be frost-bitten within a few minutes on turning a corner into the wind.
The great danger of winter mountaineering is the risk of a sudden change of weather. Storms seem to blow up out of clear skies with a suddenness to which summer affords no parallel. The man who is caught in a big winter storm is lucky if he escapes without casualty. A driving wind makes ski-ing almost impossible. The snow is blown into one’s face, and in a few minutes one’s eyelashes are gummed up with miniature icicles.
The big storms that sometimes prevail for more than a week at a time may imprison the climber in a club hut until all his provisions are exhausted. From most club huts escape is completely impossible till the storm drops. Even when the storm has given place to fine weather, retreat may be very dangerous owing to the avalanche peril.
Under fair conditions winter mountaineering is often surprisingly easy. Men who have enjoyed unbroken good luck with their weather are tempted to discount the very real dangers of mountaineering in winter, and to adopt a paradoxical attitude towards the Alps in winter, implying that the only danger to be feared is sunstroke and snow-blindness. Those who have not been so uniformly lucky realize that winter mountaineering on a big scale is a sport from which the element of danger will never be lacking; that a sudden storm may transform even an easy expedition into a desperate struggle for safety.
[Sidenote: The Approaches to the High Alps.]
Often the most difficult, and sometimes the most dangerous, part of a winter expedition in the High Alps is the first day’s march to the club hut. Once the upper regions are attained, progress is usually fairly straightforward. It is quite normal for ski-runners to make nearly as good time on the ascent of a snow-peak as summer climbers, but it is very rare indeed that the club hut is reached in anything approaching summer time. From one and a half to twice as long must be allowed for the ascent to most club huts.
The long, narrow valleys that so often lead to huts are usually very deep in soft powdery snow, so that progress must be slow, whereas in the upper regions the snow is usually more or less packed by the wind, which makes for easier going on the ascent, even though the descent may be far from pleasant. Moreover, the danger from avalanches is usually much more serious in the lower regions, where the slopes are much steeper and the valleys narrower.
On the first day’s march the guides will be heavily loaded, for the full equipment for a serious expedition in the High Alps is very much more bulky and weighty than that necessary in summer. In the first place, no prudent ski-runner commits himself to a High Alp tour without ample reserves of food. He must allow for the danger of finding himself stormbound in a hut for a period which may be anything from a day to a fortnight. Plenty of compressed reserve food is essential until the club huts begin to store emergency rations. Further, as a broken ski may involve serious consequences, he must burden himself with spare ski-tips and all the apparatus for mending ski. Extra clothes, plenty of gloves, and, of course, crampons add to the overburdened rucksacks. Unless one is prepared to carry very heavy sacks it does not pay to economize in porters. As a rule, you should reckon two guides or porters for every member of the party if you contemplate an expedition of some five to six days in length, unless, of course, you are prepared to carry some thirty pounds or so in your own sack for the first day. Of course, if you take two porters to the hut, they may be sent back from the hut; but it is obviously unfair to expect a solitary porter to make the descent alone.
Everything should be done to make matters easy. If the first part of the ascent lies up a path or a wood-track, a boy should be hired to carry your ski. If the ascent begins from some out-of-the-way alpine valley, it will often pay to send a guide on ahead the day before to make tracks for part of the distance in soft snow. This is especially useful if you are attempting a very big climb from one of the rather higher alpine valleys or mountain inns without using a club hut. It is unwise to reckon on climbing more than an average of 500 feet per hour for the first day.
An early start is essential. The longest days pass fairly comfortably if you break them up with frequent short halts and short feeds. It is often impossible in winter to make a prolonged halt owing to the cold. A few caramels or some chocolate, which can be easily got at, should be kept in one’s pocket, and munched during short halts. Napoleon’s rule of a short rest and something to eat every hour is a good rule for climbers, especially winter climbers who are heavily laden.
The huts as a rule are comfortable enough in winter, though the stoves often prove troublesome. Wood is usually kept in large quantities, brought up at the end of the autumn, though it is as well to make inquiries on this point before starting. On reaching the hut, set the aneroid barometer usually found in most huts. A pocket-barometer is not so reliable, for, as Whymper pointed out and conclusively proved, the usual aneroid tends to lose on the mercurial. In other words, if you carry a pocket-aneroid up some thousands of feet and then set it at the hut, it will usually fall a point during the night, where a mercurial barometer would have remained stationary.
So, too, if you descend from a peak to a hut, the pocket-aneroid will rise where a mercurial would remain stationary, thereby often conveying very dangerous and misleading information. It is most important to set the hut aneroid, so as to have some warning of the approach of a sudden storm.
If you are unlucky enough to be caught by bad weather in a hut, and if your provisions run short, you should spend as much of your time as possible lying down and keeping warm, for the less exercise you take the less food you will need. People who practise the ‘fast cure’ have proved that a man can go without any food for a week and carry on his ordinary business without feeling unduly weakened. It is therefore in every way better to stay at the hut fasting--even for three or four days--than to attempt to descend in a bad storm. If the worst comes to the worst, and the party is thoroughly weakened by lack of food, they can always stay at the hut and await the search party.
If a sally is attempted in bad weather from a hut which is situated among glacier snow-fields, it is advisable to cut up a number of small stakes from the firewood. These can be planted in the snow at intervals of a hundred yards or so in order that a retreat can always be made back to the hut if further advance is impossible.
[Sidenote: Snow Conditions in the High Alps.]
If the Alps were windless, the snow that falls between November and the end of February would remain powdery and unspoiled on all save very steep south slopes. At high altitudes the sun is powerless to affect the snow in midwinter on gentle south slopes. The snow would remain powdery on northern slopes till the middle of April but for wind. Unfortunately, the High Alps are swept by wind, more especially during long spells of fine cloudless weather, during which the ‘bise,’ or north wind, sweeps across all exposed ridges and faces. Consequently, the snow seldom remains long unspoiled. In sheltered glacier valleys it may retain its powdery condition, but on all more or less exposed slopes it soon hardens. Of course, if an expedition is planned within two or three days of a fresh snowfall, the party may have perfect powder snow; but such snow is the exception in winter in the High Alps, whereas it is the rule in spring.
[Sidenote: Rock Ridges and Ice Slopes.]
Rock climbing does not properly come within the scope of mountaineering on ski; but so many ski-runners combine a ski tour with a final scramble up a rock ridge, such as the last arête of Monte Rosa or the Zinal Rothhorn, that some discussion of the condition of rocks and ice slopes in winter is essential.
As a rule, rock ridges are as dry, or drier, in winter than in summer. Snow that falls in summer often falls at a temperature little below freezing. It is often most adhesive stuff. The strong summer sun followed by frosts at night turns this snow into crust, or at least into snow with a considerable power of sticking to the rocks. In summer it is often several days before the big rock peaks will go after a heavy snowfall. But in winter the snow that falls in the High Alps is light and powdery. The low temperatures and the reduced power of the sun prevent the snow melting; it retains its light powdery character, and is swept away from exposed ridges by the wind. It offers no resistance to the wind, for it is composed of light dry crystals with no cohesive or adhesive power. Consequently, the rock ridges in the winter are often freer from snow than in average summer weather, which is a mixture of good and bad. In winter, cornices have little chance of forming. In fact, if the weather is mild and the ridge windless on the day of the ascent, it is scarcely more difficult to climb a rock ridge of average difficulty in winter than in summer. South ridges are, of course, much warmer than north ridges, but they are not necessarily more free of snow; for the agent that reduces the snow on the rock ridges is not the sun--powerless as a melting agent at these altitudes in winter--but the wind; and in fine weather the wind, as often as not, blows from the north. Of course, if the north wind is blowing, a north ridge may be impossible, for the rocks promptly become extremely cold to touch, so that in general it is wisest to select south rock ridges in preference to north. None the less, rock ridges facing north, such as the north ridge of the Zinal Rothhorn or the north ridge of the Gspaltenhorn, have been climbed without difficulty in midwinter.[22]
The same causes which keep the rock ridges comparatively free from snow tend to remove any snow that may fall on to steep ice slopes.
Inexperienced winter mountaineers are often surprised to find as much or more ice on summit slopes in winter than in summer.
As a matter of fact, there is often quite as much ice on steep exposed slopes in winter as in summer.
An ice slope is transformed into a snow slope when falling snow is accompanied by a temperature just above freezing-point--in other words, when the snow is very nearly sleet. Such snow adheres to the underlying ice, and by the normal process of alternate thaw and frost becomes more and more firmly attached. The next snowfall that occurs attaches itself to the underlying thin stratum of snow crust lying on ice, so that in the course of time the ice slope is covered by a compact and reliable layer of crusted snow.
But the dry powder of midwinter has no chance of finding a permanent resting-place on steep ice. The first strong wind that blows will remove it.
Many slopes vary from season to season and from month to month. Sometimes they are ice, sometimes snow. Such slopes, if they are ice in October, will remain ice until the following spring. May and June are the months in which the conversion of ice slopes into snow slopes usually takes place.
GLACIERS IN WINTER
The light powder snow which is swept from rock and ice ridges is deposited on the broad glacier snow-fields, which therefore receive more than their fair share of snow. In midwinter there are few open crevasses to be seen, save at the icefalls, and most traces of concealed crevasses disappear from the upper névés. None the less, the danger from concealed crevasses is by no means trivial. The dry powder snow forms the most brittle of snow-bridges.
In the Grenz glacier accident a snow-bridge fourteen feet thick collapsed beneath a party of ski-runners. Of course, sooner or later, most crevasses are bridged, not only by powder snow, but various forms of wind-driven snow and wind-formed crust. Such crust is, of course, less brittle than powder snow-bridges, but it is quite brittle enough. The low temperature tends to increase the brittleness of snow-bridges.
In the early hours of a summer morning a snow-bridge two or three inches thick will usually be safe enough; for such bridges are generally formed of a mixture of ice and hard snow which is due to alternate melting and freezing. Such crust is much more compact, more solid, and far less brittle than crust formed by wind.
Glaciers are, in fact, safer in summer than in winter; for though there are many more crevasses open, there are far fewer dangerous crevasses whose existence cannot easily be detected. The droop on the snow and other unmistakable signs in ordinary seasons betray most concealed crevasses to the experienced eye. In winter the winds are so powerful, and their effect is so much greater (for reasons explained on pp. 446-447), that they obliterate all traces of underlying crevasses. The surface of the snow is apparently one uniform field of wind-driven snow, and even the most expert cannot possibly detect the presence of concealed crevasses.
This raises the very vexed question of ski-ing on a rope. It is quite easy with a little practice to ski at a reasonably high speed on a rope, and to make combined swings. Roped running is, in fact, quite enjoyable, but it is not, and never can be, as enjoyable or as easy as free ski-ing. Consequently, many ski-runners will never consent to rope on the descent, save on glaciers, which are known to be badly crevassed.
There are three methods of ski-ing on a glacier:
1. A Roped Descent.--For the technique of ski-ing on a rope, see pp. 452-456.
2. A Descent in exactly the same Tracks as were used for the Ascent.--This method is based on the presumption that a snow-bridge which held in the morning during the ascent will hold during the descent. Obviously the strain is much less during the fast descent than during the climb. Also, as the variations of temperature in winter are of no great importance, provided that the temperature remains below freezing, a snow-bridge which holds in the morning should hold in the afternoon, though the same cannot, of course, be said in summer. As the tracks of the ascent were presumably made on sealskins, the descent must also be made on sealskins if it be desired to follow with any accuracy the line of the ascent and to avoid rapid swings and turns which are liable to test severely a snow-bridge strong enough to resist the ordinary uphill track. For my part, though this method is sometimes used, I consider that the necessity to wear skins and to keep exactly along one line is just as troublesome and not nearly so safe as the rope.
What usually happens when people start a descent without skins, but with the pious intention of keeping to the uphill tracks, is that they very soon find themselves curving and swinging some considerable distance from their old tracks.
3. A Free Descent Unroped.--If you discard the rope, you should be doubly careful to reduce risk to a minimum by paying attention to the general laws of crevasse formation. The middle of a glacier is usually the safest part of the glacier in winter. Lateral crevasses, i.e. crevasses at the side of the glacier, are wider, more numerous, and more complicated than transverse crevasses. The crevasses in the middle of a glacier are usually at right angles to the line of flow, so that a ski-runner who is running straight will cross them at their narrowest breadth. Lateral crevasses usually run at an angle of 30-45 degrees to the line of flow,[23] so that they will usually be crossed by a ski-runner at a more or less wide angle, and the danger of running along the whole length instead of across a snow-bridge is therefore great.
The principal rules for glacier ski-ing in order of importance are as follows: (1) Don’t fall. (2) Don’t make sudden swings. (3) Run straight. (4) Don’t use your stick. (5) Keep to the middle of the glacier.
In other words, run as straight as you can consistent with not falling. It is better to run straight and to use your stick to reduce your speed than to check your speed by swings and turns, for a swing to a standstill above a crevasse is more likely than any other ski-ing manœuvre to break a snow-bridge.
Keep close together on the descent, but not too close. Above all things, avoid crossing the same snow-bridge while another member of the party is crossing it. In the Grenz glacier accident three members of the party fell into the same crevasse.
Avoid short sharp turns, and cultivate long gentle turns if you cannot run straight.
It is often advisable to follow the leader’s tracks, for if the leader has passed over a crevasse without falling in, the chances are that you will be equally fortunate.
There should be two ropes in the party, so that if one rope disappears with its bearer into a crevasse the second rope may be available to pull him out.
At least one rope, and, in addition, the first-aid case and mending apparatus for ski, should be in the rear of the party, as nothing is more annoying than to see the leader disappearing far below with the spare ski-tip just as your ski-point has snapped off.
“Always rope on snow-covered glaciers.” This is the law, and in theory the law admits of no exceptions. But in winter, as in summer, this law is often broken. Few climbers have a clear record on this point. The temptation to break the law is, of course, much stronger for the ski-runner than for the foot-climber. There have been comparatively few accidents in which ski-runners have fallen into crevasses. On glaciers that are known to be little, if at all, crevassed in summer, only a pedant would rope in winter. Local knowledge is therefore very useful indeed, and if a local guide can be taken, so much the better.
Such accidents as have happened have been either on the ascent, or during a more or less level traverse, or as the result of a sudden swing or stem which has disturbed the snow. I know of no case in which a ski-runner has fallen into a crevasse during a fast, free, unchecked descent. Indeed, I should doubt if it would be possible to break through a snow-bridge while moving fast and running straight. I have myself shot an open crevasse about ten feet or more in breadth while travelling at a fairly high speed.
Most ski-runners would rope in winter on a glacier that was known to be very crevassed in summer. Many ski-runners always rope in winter, but far more only rope when they know the glacier to be very crevassed.
In May or June there is no reason to rope for the descent, save under very exceptional circumstances. The risk of falling into a crevasse in May or June is so slight that the rope may usually be discarded.
[Sidenote: Ski-ing on a Rope.]
Ski-ing on a rope is not so difficult as the inexperienced might suppose. Experts who have practised together can attain high speeds, and perform all the turns while roped together. A couple of good runners with a little practice should be able to run safely at a fair speed. But practice is necessary, and an hour or two of roped running in the valley is well worth while.
Two is the most manageable number on a rope, and of course, there need never be more than three, for larger parties can divide up into two twos, a two and a three, etc.
First a word as to roping. Most guides make a loop at the very end of the rope. This is quite unsound. The loop should be made about four feet from the end of the rope, and this four feet of spare rope should again be tied round the waist. Otherwise, if you fall into a crevasse, the pressure on your waist may almost suffocate you before you are withdrawn; whereas, if you have four feet of spare rope, you can uncoil this, make a new loop into which you can place a foot, thereby at once relieving the pressure on your body. With a little effort you should be able to wriggle out of the main noose, standing in what may be called the stirrup noose. If you are not exhausted, you might then be able to swarm up the rope, which would of course be quite impossible if, as would otherwise be the case, the end of the rope was originally tied round your body. Two men on a glacier alone sometimes adopt Mummery’s plan of wearing a second rope, which, in the event of a fall into a crevasse, is untied by the man above and wound round the head of an axe driven into the snow. The man below pulls on to the rope wound round the axe. The man above pulls on to the rope round the fallen man’s body. Thus there are virtually two men pulling one.
There is another method of roping sometimes used when three ski-runners are tied to the same rope, which--though it has been employed by experienced guides--seems to me most unsound. In this method two ski-runners are tied to one rope, along which runs a small iron ring. To this ring a second rope is fastened, and to this second rope the third ski-runner attaches himself. The theory is that the third ski-runner, being attached to a rope which in turn is attached to a movable ring free to slide on the main rope, is far less constrained in his movements than if all three were on the same rope. This is true, but I should be sorry to be the third ski-runner if I was to fall into a crevasse. Suppose the other two ski-runners are on opposite sides of this crevasse. The man in the crevasse is then attached to a rope which slides helplessly with the ring along the main rope. The iron ring probably buries itself in the lower lip of the crevasse. I do not quite see how any tension is to be exerted on the secondary rope.
It is simpler to begin by considering the case of two ski-runners, A and B, running on a rope. If there is a marked difference in the ability of A and B, the poorer ski-runner should lead, for it is much easier to lead on a rope than to be the last man. The last man on the rope has to moderate his pace and his direction in accordance with the movements of the leader. If, however, A and B are equally good runners, then the leader should be the one whose ski are the faster: I do not mean the faster ski-runner, but the one whose ski are running better, either because the ski themselves are faster and more slippery, or because their owner is the heavier of the two, and therefore, other things being equal, tends to get downhill quicker. For if, on a gradual slope which is to be taken straight without braking or stemming, A (whose ski are faster) is constantly overrunning B, the rope will get mixed up with the ski, and A will have to regulate his pace by stemming or braking in order to keep the proper distance. On the other hand, if A leads, his extra speed will keep the rope taut, and the tension of the rope will enable B to keep a uniform distance.
On easy ground A and B can ski in single file. B, whose ski are slower, will be kept in line by the tension of the rope. It is not necessary nor desirable for B to follow exactly the same spoor as A: his spoor should be an inch or two to the side of, and parallel to, A’s spoor.
B must be on the look out for sudden increases in pace on the part of A: A may, for instance, come to a steeper gradient, and B, if he is not on the look out, is liable to be pulled over and pitched on to his head. Similarly B, if A runs on to a gentler gradient, will have to guard against overrunning A, and thereby rendering the rope useless; for if A and B are on the same snow-bridge they may both fall in. At least 75 feet of rope should be allowed between A and B. On easy ground this rope may be allowed to be taut; on more difficult ground B should keep a coil of rope in his hand to allow a margin in the event of A suddenly increasing his speed.
The normal position for straight running should be modified. In free running lateral strains may usually be disregarded; the main risk of a fall lies in fore and aft changes of speed. Consequently, for normal running the narrow groove and the lengthened base, as in the Telemark position, are usually preferable to a broad track. But a ski-runner on a rope is always liable to lateral strains. It is rare that one runs exactly in line; whenever one’s track is parallel rather than coincident with the track of the leader, and whenever the leader changes his direction, however slightly, the rope exercises a certain amount of sideways pull. The greater the distance between the parallel tracks, the greater the lateral tension of the rope. Consequently, the ski-runner on a rope must be prepared, not only for forward and, in the case of the leader, for backward jerks, but also for sideway strains.
The best position for roped running is to hold the ski about 8 inches apart. One ski should be a few inches ahead of the other, and the knees should be loose. The body should be slightly bent below the waist. The Telemark position is, of course, most unsound.
On average ground the ski-sticks should be held together in the left hand, leaving the right hand free to hold a spare coil of rope. If it is necessary to brake or to control your speed, you should do so by stemming and not by the stick.
On difficult ground you should use the stick to control your speed--a recourse which is seldom, if ever, justified, except when running on the rope. It is quite easy to hold both the sticks and also a spare coil of rope in your two hands; and if you intend to brake with your sticks, you must, of course, put your sticks together and get both your hands on to them. The most efficient stop turn on a rope is the Christiania helped out with the sticks. If you are unroped, a yard or two of sideslip after a sudden stop is quite a good thing, but if you are roped, you need to stop in the smallest possible compass, especially if you are leading and the man behind falls. For this purpose there is nothing to beat the stop Christiania helped out with the sticks. As a rule, however, stemming is sufficient without using the sticks. Good runners can, of course, make a series of linked turns on ski, and there are few prettier sights than a skilful party on a rope descending in a series of Stemming turns.
Whether leading or going last, always keep your partner fully informed as to your changes of speed or direction. If the back man feels that he is going to fall, he must shout out at once, so as to give the leader time to stop by a stick Christiania. Similarly the leader, if he comes to a steeper gradient, should warn his partner that the speed is likely to increase.
Be prepared to fall neatly and with the maximum of effect. Should the leader fall into a crevasse, don’t allow yourself to be dragged after him. Throw yourself on the ground, and bring your ski round, as you fall, at right angles to the track and below you. This is more difficult than might be imagined. An indifferent runner, or even a good runner who had not trained himself to expect a fall, would run a big risk of being pulled into the crevasse by the first man.
The ‘falling Christiania’ is the best method of avoiding being pulled after the leader into a crevasse.
On fairly steep slopes it is best not to run in line. A and B should run side by side. Provided the rope is long enough (and at least 75 feet should be allowed between each partner), there is no danger that A and B will fall into the same crevasse. A and B will probably not be exactly side by side. B will be just a little behind A. In other words, the line of the rope will not be exactly at right angles to the parallel lines of the two tracks cut by A and B. This side-by-side method is much easier than running in line; if A suddenly quickens in speed, the only result is that A, instead of being side by side with B, tends to run on ahead, and the two tracks tend to close up together until the speed is readjusted. So, too, if B falls suddenly, A has much more chance and more room in which to make a stop Christiania than if they were running exactly in line. Also it is not necessary for either A or B to hold a coil of rope in his hands. If the snow is smooth, the rope need not be taut between the runners if they are running side by side. It cannot be allowed to hang loose and to sweep the snow.
All that has been said above applies equally to three men on a rope: three on a rope is, however, a more difficult combination; the position of the middle man liable to both fore and aft jerks is far from enviable. The best man should be placed in the middle. It is, however, surprising how easily a party of three practised roped runners can execute straight running and even combined turns on a rope.
Ropes that are employed in winter should be new. Old summer ropes should not be used up in winter. Ropes break much more easily in winter than in summer, and the strain is much greater in the event of a fall into a crevasse owing to the greater speed on ski than on foot.
THE HIGH ALPS IN SPRING
There is a fascination about the High Alps in winter that is unique. Never are the great peaks so icily aloof, the silences of the glaciers so inviolate. No moon compares with the full moon of January shining on some great glacier causeway; no views are clearer than the summit panorama of February. None the less, winter is not the proper season for ski tours in the High Alps. It is true that the rock ridges are usually free from snow in the winter and corniced in spring, so that for expeditions which combine ski-ing with more or less difficult rock climbing, winter is preferable to spring. At the same time, it is possible to exaggerate this point. An ardent champion of winter mountaineering once cited to me the Lyskamm as a mountain that could not be climbed in May owing to cornices. Unfortunately for his case, the Lyskamm had been climbed in May. I have known the cornice on the Wetterhorn almost invisible in May, whereas in many winters it is quite formidable.
Still we may concede that rock ridges are certainly far easier in February than in May, and cornices in general much larger in spring than in winter.
And of course the snowline is lower in winter than in spring; but, as we shall try to prove, this is not of very great importance.
The winter is the season for ski tours of modest length. It is the season for what may be called sub-alpine ski-ing. (We need some handy expression in English for the most useful German word Mittelgebirge.) Spring, on the other hand, is eminently suitable for ski tours in the High Alps.
The best month for glacier ski-ing is May. June is also excellent. Indeed, from about the middle of May to the middle of June is, on the average, as good a month as any in the year for glacier ski-ing.
February is usually the best of the winter months, and May is the best month for spring ski-ing. May is, among other things, usually fine. April is almost always stormy; but the weather usually mends at the end of April, and a long spell of perfect weather is as common in May as in February.
Let us then compare ski-ing among the glaciers in May and in February from the point of view of (1) Safety; (2) Quality of ski-ing; (3) Effort; (4) Scenery.
(1) Safety.--The shortness of the days and the great variations of temperature, from mild and equable to bitterly cold, all add an element of danger to the High Alps in February. A small mishap may have very serious consequences. A broken leg half-way down Monte Rosa or the Wetterhorn probably means a night in the open, and a night in the open may mean a fatal ending. The sudden changes of weather, the storms that rise in a night and last for days, all make February ski-ing among the glaciers a sport with its own dangers. In May all these risks are reduced almost to vanishing-point. A broken leg is a broken leg in February or in May, but a night in the open in May should have no permanent effect on any but a very badly wounded climber.
We have already dealt with avalanches. Here we need only repeat that though avalanches are of daily occurrence in May, an experienced party has no difficulty in avoiding them. They have a regular time-table, and, provided one times one’s ascent or descent so as to avoid crossing certain slopes at certain hours, one is absolutely safe. In winter, avalanches can fall at any hour of the day, under certain circumstances, and at any temperature. To take a concrete example: the Gauli hut. This hut lies at the head of a very steep and narrow valley, the Urbachthal. In winter one would never be quite safe in this valley. A sudden wind might rise and bring down a powder avalanche; and even in steady weather the risk of a powder avalanche from the very steep sides of this valley is never entirely absent.
In spring one leaves Meiringen before midnight, climbs this valley at night, and, provided the weather is fine, one is absolutely safe; for in spring, avalanches fall in the afternoon and never fall at night, save when the Föhn is blowing. And when the Föhn is blowing the ski-runner stays at home, or remains in a club hut.
Finally, the glaciers are not oversafe in winter, for reasons explained on pp. 448-449. In May all save very badly crevassed glaciers can be descended on ski by an unroped party, without greater risks than those which must be faced by every bold pedestrian that crosses Piccadilly Circus. The crevasses are never so securely bridged as in spring.
(2) Quality of the Ski-ing.--In winter it is the exception to find good snow in the High Alps. The wind, as has already been explained, spoils the snow on all exposed slopes. But in May the wind is powerless, for the first fine day and hot sun will melt the snow so thoroughly that all traces of wind action during the snowfall will entirely disappear. Thenceforward the wind is powerless, for the wind cannot churn up the heavy melted snow of spring, still less the hard crust which is found in the early morning.
Snow in spring is hard crust in the early morning, Telemark crust up to midday or later on high north slopes. In the afternoon it is usually soft and heavy, but in the evening it once again yields fine ski-ing.
The ski-runner who visits the High Alps in winter can form no forecast as to the possible conditions of the snow, for the snow is dependent on the direction and on the strength of the winds that have blown since the snow fell. It is therefore a matter of chance whether the snow is good or bad, for nobody can foretell the conditions which depend on such a fickle element as the wind. The longer fine weather endures in winter, the greater the chance that the snow will be spoiled. In spring the reverse is the case. The more often snow is melted and refrozen the better it becomes. In general, provided the weather remains fine, the spring ski-runner can count almost with certainty on perfect ski-ing and perfect snow.
An important point in favour of spring is the fact that one usually gets good ski-ing for every foot that one climbs on snow. In winter the summit snow slopes are often so windswept, that the ski are left some distance below the actual top and the final ascent is made on foot. In spring the snow is just as good on the most exposed summit slope as lower down. I have started spring or summer ski descents from the actual summits of such peaks as the Dom, Ebnefluh, Galmihorn, etc. This is an important advantage, and more than counterbalances the fact that the snowline is higher in May than in February; for though one may lose a thousand feet of ski-ing on the last day, one more than balances this loss by the fact that good ski-ing is obtained from the highest limit of the snow.
The snowline in May usually extends down to 5000 feet. I have spent three May months in the Alps, and I have always been able to get good ski-ing well on to the middle of May down to about 5500 feet, and sometimes lower. In narrow valleys the remains of spring avalanches survive into the summer. I have skied in the middle of June below 6000 feet in the Gredetschthal, and I have often, in the middle or end of June, obtained first-class ski-ing below 7000 feet.
Of course the height of the snowline is of no very great importance if, as is usually the case, one spends four or five days on the glaciers. One can sacrifice a thousand or two thousand feet of ski-ing on the last day with complete composure if one is certain, as one is never certain in winter, that one will get really good ski-ing for every foot of snow slope that one climbs.
(3) Effort.--Much less energy is expended on a spring than on a winter ski tour. In winter most of the climbing is done on ski. Tracks have to be made in the soft snow; a gradual zigzag course has to be taken; time is wasted over ‘kick turns.’
In spring one climbs on foot or on crampons. The ski are dragged behind on string. On level or gentle slopes the weight of the ski is almost imperceptible if they are pulled along on string. On steep slopes they are by no means a great hindrance. It is surprising what can be accomplished by a man who is dragging instead of carrying ski. I have seen Knubel climb a short but very steep snow and ice wall in which he had to cut half a dozen handholds, and on which he had to steady himself with one hand while he cut hand and foot holes with the axe held in his right hand. Meanwhile his ski were dangling on string--attached to his waist--over the bergschrund below.
The ski should, of course, always be secured by two strings in case one breaks.
In spring on hard snow one climbs very nearly as fast dragging one’s ski as one would climb without ski, and from 50-100 per cent faster than one would climb if one was forced to ascend the same slope on ski with soft winter snow.
The saving of effort is as remarkable as the saving of time, for it is much easier to climb direct on foot than to zigzag up soft snow on ski.
Apart from the upper snows, the approaches to the High Alps are easier in spring than in winter. The snow at night is nearly always hard in May. The narrow valleys, filled with soft powder snow, are covered with a firm groundwork of hard crust in spring. The climb to the club hut is usually done at night or in the early morning. Though the snow lies down to five thousand feet well on into the middle or end of May, so that the ski descent can be prolonged down to very low levels, it is usually possible to pick a route up snow-free slopes (either on southern or south-westerly or south-easterly slopes) far higher than the lowest levels of the snowline. Paths can be utilized instead of snow slopes, more especially if the peasants have begun to tramp out the paths for their own purposes. The long detours, often necessary in winter, to avoid dangerous avalanche slopes are needless in spring, for such slopes can always be crossed with safety at night when the snow is crusted.
(4) Scenery.--I have tried to show that the High Alps yield better and safer ski-ing in May than in winter. Even if this were not so, May would possess a charm for the mountaineer that no other month affords. It is perhaps idle to compare the rival beauties of the four great alpine seasons, for, even if one season could be proved paramount, the true mountaineer would wish to study the mountains in all their moods. The icy virginity of the High Alps in winter reveals secrets that are hidden in spring and in summer.
None the less, if it be permitted to state a preference, I for one should give my vote to May months. Contrast is the greater teacher, and May is the month of contrasts. I think of moments when one stepped on to a high ridge after hours among the burning snow-fields of May, and looked down, with a shock of surprise, on to the valleys dressed in a green that was different, transfigured, miraculous--a green that the valley-dweller has never seen. I think of quiet evenings after long days among the snows, when one strolled down through the scented pines with one’s ski on one’s back and the music of a perfect run still echoing in one’s heart--of the Dollfuss in May, a little oasis of green young turf covered with gentian and anemone in a wilderness of burning snow and granite ridges. I think of a sunset hour just above Rosenlaui, following four perfect days among the May glaciers, the foreground of marsh-marigolds a sheet of flame, and the whole valley one full-throated chorus of spring. Running water is always beautiful, but there is no music in all the harmonies of Nature to compare with mountain torrents in spring after days among the dead silence of the upper snows. Such are the contrasts that reward the mountaineer in May. Within the compass of dawn and sunset he can live through the cycle of the seasons, can pass from winter to spring, can enjoy the best that snow yields to the ski-runner, and the chiefest rewards that the hills yield to those that explore them when the great rebirth of colour and music has finally prevailed over the stubborn obstinacy of the retreating snows.
In order to understand the conditions that prevail in the High Alps in spring, the effect of sun on snow and the various habits of sun-formed and sun-melted crust must be grasped. These are dealt with on pp. 412-417. Avalanches are analysed on pp. 423-438. All that now remains is to consider the application of the principles laid down to the various months of spring.
[Sidenote: March.]
The winter of the calendar ends officially on 23 March, and the calendar spring lasts from 24 March to 23 June. None the less March, whatever the calendar may say, is winter in the High Alps. The snow, unless disturbed by wind, remains powdery on all north slopes and gentle south slopes. March is often a month of snowstorms, though occasionally it is distinguished by really fine weather. On the whole, however, it cannot be said to be a good month for glacier ski-ing, though, on the other hand, the days are longer than in February. The sun is stronger and the crevasses more securely bridged.
[Sidenote: April.]
April marks the transition from winter to spring. As a rule, April is marked in the Alps by frequent storms, varied by periods of wet Föhn. Occasionally one gets a week of really good weather and fine ski-ing, even at very low altitudes, and it often happens that the last week in April is perfect succeeding to a long period of snowstorms. But as a rule good weather is less common in April than in any month of the alpine year.
The snow itself varies. Powder snow is found on north slopes at high altitudes. South slopes are usually crusted. The crust varies a great deal, and resembles, in general, the crust found in winter at low altitudes. In other words, April crust on the glaciers is usually marble crust in the early mornings. The law, explained on p. 414, “The milder the frost the better the crust,” often gives the clue to timing a successful descent. As one descends on an early morning in April the crust usually improves.
As a rule, the sun is strong enough to melt the crust just before or just after midday, and in this case you get perfect running on Telemark crust. Owing to the lower temperature the snow remains good much longer than in May. In fact, at high altitudes it seldom becomes completely thawed, so that the ski-ing on April afternoons is usually better than on May afternoons.
It is important to notice that when, as in spring and summer, the sun remains above the horizon after 6 p.m., the northern slopes will be in the sun after the southern slopes have lost the sun, for the sun at 6 p.m. is due west and after 6 p.m. is north of west. Of course, as the sun is low in the sky only north slopes that are not shut in by neighbouring slopes will keep the sun.
If a north wind is blowing, the snow on north slopes, previously crusted by sun and frost, may remain quite unmelted throughout the day. I have found hard slippery crust in the late afternoon at the end of April just below the rocks of the Zinal Rothhorn, with the result that the ski-ing was most unpleasant. A bitter north wind was blowing at the time. So, too, south slopes when the north wind is blowing may resist the sun, and though they will not, like north slopes, remain really hard, they will not be thoroughly melted.
If you are lucky enough to get fine weather, April ski-ing is often delightful. After a few days of sun traces of wind action disappear from all slopes, save perhaps north slopes at very high altitudes. Telemark crust towards midday, and even later, and salt snow or hypo snow (p. 417) as you descend from the glaciers to the lower regions, are characteristic of April ski-ing.
It may be necessary to time your descent to the valley so as to pass a dangerous slope before the sun has struck it. With ordinary caution an experienced party should run no risk whatever of being caught by an avalanche; but it is undeniable that inexperienced parties come to grief more frequently in April than in any other month. This does not prove that the avalanche danger is really greater, but only that it is greater for the inexperienced.
[Sidenote: May.]
In May newly fallen snow usually remains powdery for one or two days on north slopes, and even longer at high altitudes. But, in general, powder snow is the exception in May. At high altitudes you will find hard marble crust in the early morning. At lower altitudes you will usually find ‘film crust’ and ‘perforated crust.’ For the formation of these excellent running surfaces, see p. 414.
The main difference between marble crust on the one hand, and either film crust or perforated crust on the other hand, is that the former is too slippery to give the ski purchase, whereas film or perforated crust is a splendid surface for Stemming turns or Christianias.
As a rule, in spring one descends after the sun has softened the crust. Whether the original morning crust was hard and slippery, or covered by a film or perforated crust, does not matter once the sun has melted its surface.[24] In any case, there will be a period of ski-ing on Telemark crust (p. 415). The main importance of film or perforated crust is its value when you have to begin a descent before the sun has softened the snow. I remember starting one morning just after the dawn from the Oberaarjoch. I intended to ski down to the Grimsel and thence to climb the Galenstock, and I hoped to go from the Oberaarjoch hut to the Furka between dawn and sunset, taking the Galenstock en route. It was obvious that an early start was necessary. At that date I had done little ski-ing in June, and I fully expected that the top slopes of the Oberaarjoch would be covered by very hard and slippery marble crust. To my great surprise the crust, though hard, was covered by a beautiful film of soft, transparent brittle ice. As the ski swung round on a turn, this soft film peeled away and rustled down the slope with a soft splashing sound. No surface could be finer. Straight running was absolutely safe on the even, unchanging gradients of those summit slopes. There were no hidden rocks or hidden crevasses to fear. The film crust was absolutely true. There was no risk of running into a soft sticky patch or a windswept pocket. One could run as fast as one liked, secure in the knowledge that at any moment one could stop by a long-drawn-out Christiania. On really steep slopes one could link a succession of sweeping Christianias, the loveliest of all conceivable turns, and on gentle slopes one could run straight. The soft film gave an excellent purchase and prevented the ski side-slipping helplessly as one began to turn, for the ski cut in under the film and peeled it away.
Until a man has skied down from some glacier pass at dawn on film crust he has yet to learn the best that ski-ing can yield. That run from the Oberaarjoch stands out as one of the finest runs of my life. The great charm of film crust is that fast running can be combined with absolute safety, for a dangerous fall is almost impossible on this surface. I remember that we took twenty minutes from the pass to the snout of the glacier, and duly arrived at Gletsch after taking the Galenstock en route before sunset.
Perforated crust is harder and firmer than film crust. On very steep slopes it is a little too slippery, but on anything below 25 degrees it gives perfect running.
In May film crust and perforated crust are common in the early morning, and marble crust is unusual. After fresh snow one finds all sorts of shades of snow from pure winter snow to film crust, but a few days of cloudless weather is usually sufficient to change powder into crust on all but very high north slopes.
[Sidenote: June.]
June differs mainly from May in that the snowline is higher and that winter snow is even more uncommon. Film crust and perforated crust is the rule at all save high altitudes and just after fresh snow.
As a rule the snow is even better in June than in May. The more frequently spring snow is melted and refrozen the better it becomes. Old snow that has passed through this process again and again acquires a granular and crystalline character. It does not melt so thoroughly. Provided there is no touch of Föhn in the air, it retains this crystalline form even when it is melted. In June the snow remains good for ski-ing much later in the day than in May, even though the sun is higher in the sky. In May the period of transition from wet snow to crust is very sudden. One moment the snow is wet and heavy, and half an hour later the first crust has formed. In June there is often a well-marked intermediate period when the snow gradually gets colder and more crystalline. This granular snow is very fast and very true, and suitable for every kind of turn and swing at high speed. On May evenings the soft crust is very pleasant, but it is a little too soft and the snow underneath the crust is a little too woolly; but in June when the sun goes off the slopes the snow becomes crystalline, cold, fast and just compact enough to prevent the ski sinking in too deep.
In June the lower limits of the névé often show signs of furrowing. The action of the sun forms ridges and furrows producing a wavy effect. These ridges are unpleasant to ski on or to ski over when the snow is hard, but quite harmless when the snow has begun to soften. On steep slopes the ridges run roughly parallel with the fall of the slope. On the level the snow is divided into numberless little hillocks with corresponding holes.
The action is similar on a small scale to the erosive action of water on a large scale. Water furrows an even mountain side with gullies and a more or less level plain with intersecting ravines that produce a series of hills. And just as in the geological cycle the last stage of a mountainous country is a peneplane, so on snow the action of the sun acts on the ridges and hillocks formed by previous action of the sun and once again reduces the surface to a plain. I have seen in winter one heavy rainstorm furrow the hillsides with miniature ridges and a level snow slope with miniature hillocks, and I have seen the next rainstorm--which followed two days later--erode the ridges and hillocks formed by the first storm and once again produce slopes of even contour and levels unbroken by hillocks.
THE SPRING TIME-TABLE
The spring ski-runner has, in general, the choice of two periods of the day for his descent. He can descend in the morning just after the sun has begun to soften the surface of the hard crust, or in the evening when the soft melted snow is beginning to freeze again. If the day’s run ends at some club hut situated at a reasonable height, say 9000-10,000 feet, he can usually leave the hut about dawn and return about midday, for the snow at this height is usually perfect just before midday; or he can time his descent for just before or just after sunset. If he is descending to the valley, it is usually best to time his descent a great deal earlier. In May the snow below 8000 feet softens very quickly directly the sun touches it, and becomes dangerous on steep slopes. In this case, should the snow on the glaciers be film or perforated crust, he can start his descent before the sun has softened the crust, so as to reach the lowest limits of the snow before they have been softened by the sun.
As this is often impossible, it is best to time the descent from the peak to the club hut for midday, or rather before midday, and then to wait in the hut till sunset, and continue the run down to the valley after the sun has set and the snow begun to freeze again. Guides are often dreadfully impatient, and have the greatest objection to spending a long time on the summit of a peak. Many guides seem to regard summit views with studied malevolence, and very few guides really understand spring snow. If, as often happens, the arrival on the summit occurs after midday, it is absurd to spoil a perfect descent by running down in the afternoon. The amateur must exercise reasonable restraint and insist on waiting. There are many things more unpleasant than to lie about on the summit of some great peak for three or four hours studying the changing effect of a May afternoon on distant hills and valleys, what time the snow gradually improves.
Great judgment is required in spring to get the best value out of the descent; it will often pay a party to wait three or four hours for the snow to improve. Summer climbers seldom linger on the summit, for in summer the wind usually makes itself felt, but in May or June one can bask on the top of a peak in shirt sleeves even after the sun has set.
Eastern slopes, of course, are the first to soften in the morning and the first to freeze at night. The best moment to descend varies with the orientation of a slope. It is often possible to choose one of two alternatives,--an eastern or a western route,--and the wise ski-runner can often improve the quality of the descent by a clever choice of line and slope.
Considerable experience is needed after a fresh fall of snow. Snow usually remains powdery for a day or two on north slopes in May or June. Perfect powder snow is by no means the exception in spring; an inch or two of winter powder on spring crust provides a surface which is absolutely unrivalled. When, however, the powder begins to turn into crust the ski-ing may often be difficult. After a snowfall you should try either to find slopes holding winter snow or slopes holding spring snow, but not slopes on which the snow is just changing from powder to crust. You may, for instance, have spent the night at a club hut at a height of 9000 feet above the sea. You have arrived in the middle of June on the first fine day after a snowstorm. The snow near the hut has been thoroughly melted by the sun before your arrival. The weather is clear, and there is a north wind blowing. You may reasonably expect powder snow on north slopes down to about 10,000 feet, so that if you have a choice of an expedition on north snow, say a peak 13,000 feet high, you should attempt it, and you will probably find powder snow most of the way. On the other hand, a peak of the same height that faced south might be an unpleasant condition, powder turning into sticky snow or crust. It might therefore be best to choose a small peak, say 11,000 feet, facing south, and run down below the hut, remounting in the evening. Such an expedition might yield better ski-ing than a high peak.
After a day or two of fine weather all snow, excepting snow on north slopes at a very great height, is transformed into ordinary spring snow. Thenceforward the ski-runner may count on perfect snow, provided he times his descent right.
It is only with forty-eight hours of a snowfall that there is any real difficulty. During such short periods the experienced spring ski-runner will know whether to go for north slopes in the hope of winter snow or for southern slopes, or north slopes at lower altitudes, in search of spring snow.
SUMMER AND AUTUMN SKI-ING
In summer the snowline climbs ever higher, and the scope of the ski-runner is accordingly limited. Climbers who go straight up a peak and down again to the valley will therefore be unwilling to burden themselves with ski; but for a man who spends several days in club huts without ever descending far below the summer snowline, the use of ski for snow-peaks is as valuable as at any other season of the year. Monte Rosa, Ebnefluh, Fiescherhorn, etc., yield quite as good ski-ing down to the club-hut levels in August as in January--better, in fact, for the snow is usually better in August than in January.
Of course the crevasses are more open than in spring, and the greatest care is needed after a fresh fall of snow.
The snow conditions as the summer advances gradually change. July is not unlike June, excepting that there is less snow on the mountains and that the snowline is higher. Otherwise one finds in July all the varieties of spring snow from film crust to granular snow.
On 20 August the sun is at the same altitude as on 20 April, and on 20 September it is at the same altitude as on 20 March. So that towards the end of September we should expect that the sun would be powerless to affect powder snow on north slopes just as it is powerless at the end of March to transform powder into crust on north slopes at reasonably high altitudes.
In August powder snow on north slopes usually remains uncrusted for two or three days after a fall. The wind, which was powerless in May or June, begins to regain its ascendancy. In August one finds at high altitudes on north slopes all the usual effects of wind action that one may observe in April. One does not see the same traces of wind that one observes in January, for the snowfalls are lighter and the sun is stronger, but windboard and rippled snow are common enough in August.
In September and October snow remains powdery unless affected by Föhn on north slopes above 9000 feet.
In October the snowfalls usually begin at the ordinary alpine centres. I have enjoyed perfect ski-ing at Mürren by the middle of October; ski expeditions in the High Alps have also been carried out at this date, though the practice is to be discouraged; for, of course, the glaciers are never so dangerous as in October or November, when the maximum number of crevasses are open and the snow bridges more insecure than at any other period of the year.
In a few years’ time many club huts will be provided with ski, so that the trouble of carrying ski to the summer snowline will no longer exist. When once this obstacle to summer ski-ing is removed, I confidently expect that it will be the exception rather than the rule to see climbers ascending Monte Rosa or similar peaks without ski at any period of the year.
SUMMER SKI
Short summer ski are very useful. A handy size is about 5½ feet in length. Such ski are very light and easily carried, and can be tied on between the rucksack and the back. They are becoming very popular, and have a great future.
On hard snow short ski are nearly as fast and as steady as long ski. On soft snow they are, of course, nothing like so fast, and are apt to be jerky and unpleasant if the snow varies in density or in speed. On steep slopes of soft snow they are quite as good as long ski, for they are very easy to turn; and so long as the slope is steep enough to descend with continuous turns, short ski are as good or better than long ski. It is on gradual slopes of soft snow or crust that their disadvantage is marked.
They are amazingly handy for really steep narrow slopes, such as gullies. On short summer ski one can descend a gully 40 degrees steep and about 12 feet wide with sharp continuous turns. Stemming turns and Christianias are ridiculously easy.
Mountaineers who have never been on ski will find short ski quite easy to manage. A man who can glissade with safety down a steep gully will be able to ski almost at once on good snow and on easy slopes without too many falls, and should be able to make slow turns on short ski after a day or two’s practice. Provided the snow is good, the average névé is an ideal practice-ground for beginners owing to the absence of obstacles.
Even very short ski, 3 feet or 4 feet in length, are a great deal better than no ski. On steep slopes they are most useful, and even on gentle slopes, provided the snow is hard, one can get a really fine run on a pair of ski no more than a yard in length.
FOOTNOTES:
[18] I may perhaps refer the reader to my own book Cross Country Ski-ing (Methuen) or to V. Caulfeild’s book How to Ski for the technique of ski-ing.
[19] I am ignorant of physics and should be glad to have this guess corroborated by a physicist.
[20] Eastern slopes retain powder snow rather longer than western slopes, possibly because the morning sun is less powerful than the evening sun, as the atmosphere warms up as the day proceeds. Further, as the prevailing alpine winds blow from the west, slopes that face east are less often spoiled by wind than those which face west.
[21] Sometimes when the night is unusually mild the crust is not sufficiently firm, and at the first touch of sun, it does not merely melt superficially producing Telemark crust, but gives under the ski and yields very nasty running. This is usually the case at low altitudes in May.
[22] As the prevailing alpine winds blow from the west, western rock ridges and rock faces are usually more free from snow than eastern ridges. See footnote, p. 409.
[23] As the middle of the glacier moves faster than the sides, and as the line of cleavage is at right angles to the line of tension, lateral crevasses, contrary to what casual deduction might suppose, run backwards from the side of the glacier to the centre.
[24] Provided that the night has been cloudless. An overcast sky, or Föhn, will only produce a very weak crust which gives at once when the sun rises. See footnote on p. 415. A couple of hours of a cloudless sky is, however, quite enough to produce a good firm crust at night.