Hazards

The craft of climbing has been developed to avoid three main types of danger: the danger of things falling on the climber (objective danger), the danger of the climber falling and inclement weather. The things that may fall include rocks, ice, snow, other climbers or their gear; the mountaineer may fall from rocks, ice or snow, or into a crevasse. In all, there are eight chief dangers: ,falling rocks, falling ice, snow-avalanches, falls,the climber falling falls from ice slopes, falls down snow slopes, falls into crevasses and dangers from weather. To select and follow a route using one's skills and experience to mitigate these dangers is to exercise the climber's craft.

Falling rocks

Every rock mountain is slowly disintegrating due to erosion, the process being especially rapid above the snow-line. Rock faces are constantly swept by falling stones, which are generally possible to dodge. Falling rocks tend to form furrows in a mountain face, and these furrows (couloirs) have to be ascended with caution, their sides often being safe when the middle is stoneswept. Rocks fall more frequently on some days than on others, according to the recent weather. Ice formed during the night may temporarily bind rocks to the face but warmth of the day or direct sun exposure may easily dislodge these rocks. Local experience is a valuable help on determining typical rockfall on such routes.

The direction of the dip of rock strata often determines the degree of danger on a particular face; the character of the rock must also be considered. Where stones fall frequently debris will be found below, whilst on snow slopes falling stones cut furrows visible from a great distance. In planning an ascent of a new peak mountaineers must look for such traces. When falling stones get mixed in considerable quantity with slushy snow or water a mud avalanche is formed (common in the Himalaya). It is vital to avoid camping in their possible line of fall.

Falling ice

The places where ice may fall can always be determined beforehand. It falls in the broken parts of glaciers (seracs) and from overhanging cornices formed on the crests of narrow ridges. Large icicles are often formed on steep rock faces, and these fall frequently in fine weather following cold and stormy days. They have to be avoided like falling stones. Seracs are slow in formation, and slow in arriving (by glacier motion) at a condition of unstable equilibrium. They generally fall in or just after the hottest part of the day, and their debris seldom goes far. A skillful and experienced ice-man will usually devise a safe route through a most intricate ice-fall, but such places should be avoided in the afternoon of a hot day. Hanging glaciers (i.e. glaciers perched on steep slopes) often discharge themselves over steep rock-faces, the snout breaking off at intervals. They can always be detected by their debris below. Their track should be avoided.

Falls from rocks

The skill of a rock climber is shown by one's choice of handhold and foothold, and his adhesion to those one has chosen. Much depends on a correct estimate of the firmness of the rock where weight is to be thrown upon it. Many loose rocks are quite firm enough to bear a person's weight, but experience is needed to know which can be trusted, and skill is required in transferring the weight to them without jerking. On rotten rocks the rope must be handled with special care, lest it should start loose stones on to the heads of those below. Similar care must be given to handholds and footholds, for the same reason. When a horizontal traverse has to be made across very difficult rocks, a dangerous situation may arise unless at both ends of the traverse there be firm positions. Mutual assistance on hard rocks takes all manner of forms: two, or even three, people climbing on one another's shoulders, or using an ice axe propped up by others for a foothold. The great principle is that of co-operation, all the members of the party climbing with reference to the others, and not as independent units; each when moving must know what the climber in front and the one behind are doing. After bad weather steep rocks are often found covered with a veneer of ice (verglas), which may even render them inaccessible. Crampons are useful on such occasions.