It is comparatively seldom, however, that an ascent of a great mountain can be executed exclusively upon snow and glacier. Ridges peep through which have to be surmounted. In my earlier scramblings I usually took to, or was taken upon, the summits (or arêtes) of the ridges, and a good many mountaineers habitually take to them on principle, as the natural and proper way. According to my experience, it is seldom well to do so when any other course is open. As I have already said, and presently shall repeat more particularly, the crests of all the main ridges of the great peaks of the Alps are shattered and cleft by frost; and it not unfrequently happens that a notch in a ridge, which appears perfectly insignificant from a distance, is found to be an insuperable barrier to further progress; and a great detour, or a long descent, has to be made to avoid the obstacle. When committed to an arête one is tied, almost always, to a particular course, from which it is difficult to deviate. Much loss of time must result if any serious obstruction occurs; and total defeat is not at all improbable.
But it seldom happens that a great alpine peak is seen that is cut off abruptly, in all directions, from the snows and glaciers which surround it. In its gullies snow will cling, although its faces may be too steep for the formation of permanent snow-beds. The merits of these snow-gullies (or couloirs) have been already pointed out,[1] and it is hardly necessary to observe, after that which was just now said about snow, that ascents of snow-gullies (with proper precautions) are very much to be preferred to ascents of rocky arêtes.
By following the glaciers, the snow-slopes above, and the couloirs rising out of them, it is usually possible to get very close to the summits of the great peaks in the Alps. The final climb will, perhaps, necessarily be by an arête. The less of it the better.
It occasionally occurs that considerable mountain slopes, or faces, are destitute of snow-gullies. In that case it will, very likely, be best to adhere to the faces (or to the gullies or minor ridges upon them) rather than take to the great ridges. Upon a
