Modern Painters, Volume 4 (of 5)

by John Ruskin

The heap formed by the sand falling in an hour-glass presents, in its straight sides, the simplest result of such a condition; and any heap of sand thrown up by the spade will show the slopes here and there, interrupted only by knotty portions, held together by moisture, or agglutinated by pressure,—interruptions which cannot occur to the same extent on a large scale, unless the soil is really hardened nearly to the nature of rock. As long as it remains incoherent, every removal of substance at the bottom of the heap, or addition of it at the top, occasions a sliding disturbance of the whole slope, which smooths it into rectitude of line; and there is hardly any great mountain mass among the Alps which does not show towards its foundation perfectly regular descents of this nature, often two or three miles long without a break. Several of considerable extent are seen on the left of [Plate 46].

§ 15. I call these lines of rest, because, though the bulk of the mass may be continually increasing or diminishing, the line of the profile does not change, being fixed at a certain angle by the nature of the earth. It is usually stated carelessly as an angle of about 45 degrees, but it never really reaches such a slope. I measured carefully the angles of a very large number of slopes of mountain in various parts of the Mont Blanc district. The few examples given in the note below are enough to exhibit the general fact that loose débris lies at various angles up to about 30° or 32°; débris protected by grass or pines may reach 35°, and rocky slopes 40° or 41°, but in continuous lines of rest I never found a steeper angle.[98]

§ 16. I speak of some rocky slopes as lines of rest, because, whenever a mountain side is composed of soft stone which splits and decomposes fast, it has a tendency to choke itself up with the ruins, and gradually to get abraded or ground down towards the débris slope; so that vast masses of the sides of Alpine valleys are formed by ascents of nearly uniform inclination, partly loose, partly of jagged rocks, which break, but do not materially alter the general line of ground. In such cases the fragments usually have accumulated without disturbance at the foot of the slope, and the pine forests fasten the soil and prevent it from being carried down in large masses. But numerous instances occur in which the mountain is consumed away gradually by its own torrents, not having strength enough to form clefts or precipices, but falling on each side of the ravines into even banks, which slide down from above as they are wasted below.

§ 17. By all these various expedients, Nature secures, in the midst of her mountain curvatures, vast series of perfectly straight lines opposing and relieving them; lines, however, which artists have almost universally agreed to alter or ignore, partly disliking them intrinsically, on account of their formality, and partly because the mind instantly associates them with the idea of mountain decay. Turner, however, saw that this very decay having its use and nobleness, the contours which were significative of it ought no more to be omitted than, in the portrait of an aged man, the furrows on his hand or brow; besides, he liked the lines themselves, for their contrast with the mountain wildness, just as he liked the straightness of sunbeams penetrating the soft waywardness of clouds. He introduced them constantly into his noblest compositions; but in order to the full understanding of their employment in the instance I am about to give, one or two more points yet need to be noticed.

§ 18. Generally speaking, the curved lines of convex, fall belong to mountains of hard rock, over whose surfaces the fragments bound to the valley, and which are worn by wrath of avalanches and wildness of torrents, like that of the Cascade des Pélerins, described in the note above. Generally speaking, the straight lines of rest belong to softer mountains, or softer surfaces and places of mountains, which, exposed to no violent wearing from external force, nevertheless keep slipping and mouldering down spontaneously or receiving gradual accession of material from incoherent masses above them.

§ 19. It follows, rather, that where the gigantic wearing forces are in operation, the stones or fragments of rock brought down by the torrents and avalanches are likely, however hard, to be rounded on all their edges; but where the straight shaly slopes are found, the stones which glide or totter down their surfaces frequently retain all their angles, and form jagged and flaky heaps at the bottom.

And farther, it is to be supposed that the rocks which are habitually subjected to these colossal forces of destruction are in their own mass firm and secure, otherwise they would long ago have given way; but that where the gliding and crumbling surfaces are found without much external violence, it is very possible that the whole framework of the mountain may be full of flaws; and a danger exist of vast portions of its mass giving way, or slipping down in heaps, as the sand suddenly yields in an hour-glass after some moments of accumulation.

§ 20. Hence, generally, in the mind of any one familiar with mountains, the conditions will be associated, on the one hand, of the curved, convex, and overhanging bank or cliff, the roaring torrent, and the rounded boulder of massive stone; and, on the other, of the straight and even slope of bank, the comparatively quiet and peaceful lapse of streams, and the sharp-edged and unworn look of the fallen stones, together with a sense of danger greater, though more occult, than in the wilder scenery.

J. M. W. Turner.	J. Cousen.
50. Goldau.