| Fig. 6. |
§ 5. Such, however, is the simple fact, that when the compact pact crystallines are about to pass into slaty crystallines, their mica throws itself into these bands and zones, undulating around knots of the other substances which compose the rock. Gradually the knots diminish in size, the mica becomes more abundant and more definite in direction, and at last the mass, when broken across the beds, assumes the appearance of [Fig. 6] on the last page.[46] Now it will be noticed that, in the lines of that figure, no less than in [Fig. 5], though more delicately, there is a subdued, but continual expression of undulation. This character belongs, more or less, to nearly the whole mass of slaty crystalline rocks; it is one of exquisite beauty, and of the highest importance to their picturesque forms. It is also one of as great mysteriousness as beauty. For these two figures are selected from crystallines whose beds are remarkably straight; in the greater number the undulation becomes far more violent, and, in many, passes into absolute contortion. [Fig. 7] is a piece of a slaty crystalline, rich in mica, from the Valley of St. Nicolas, below Zermatt. The rock from which it was broken was thrown into coils three or four feet across: the fragment, which is drawn of the real size, was at one of the turns, and came away like a thick portion of a crumpled quire of paper from the other sheets.[47]
| Fig. 7. |
§ 6. I might devote half a volume to a description of the fantastic and incomprehensible arrangement of these rocks and their veins; but all that is necessary for the general reader to Typical character of Slaty Crystallines. know or remember, is this broad fact of the undulation of their whole substance. For there is something, it seems to me, inexpressibly marvellous in this phenomenon, largely looked at. It is to be remembered that these are the rocks which, on the average, will be oftenest observed, and with the greatest interest, by the human race. The central granites are too far removed, the lower rocks too common, to be carefully studied; these slaty crystallines form the noblest hills that are easily accessible, and seem to be thus calculated especially to attract observation, and reward it. Well, we begin to examine them; and first, we find a notable hardness in them, and a thorough boldness of general character, which make us regard them as very types of perfect rocks. They have nothing of the look of dried earth about them, nothing petty or limited in the display of their bulk. Where they are, they seem to form the world; no mere bank of a river here, or of a lane there, peeping out among the hedges or forests: but from the lowest valley to the highest clouds, all is theirs—one adamantine dominion and rigid authority of rock. We yield ourselves to the impression of their eternal, unconquerable stubbornness of strength; their mass seems the least yielding, least to be softened, or in anywise dealt with by external force, of all earthly substance. And, behold, as we look farther into it, it is all touched and troubled, like waves by a summer breeze; rippled, far more delicately than seas or lakes are rippled; they only undulate along their surfaces—this rock trembles through its every fibre, like the chords of an Eolian harp—like the stillest air of spring with the echoes of a child's voice. Into the heart of all those great mountains, through every tossing of their boundless crests, and deep beneath all their unfathomable defiles, flows that strange quivering of their substance. Other and weaker things seem to express their subjection to an Infinite power only by momentary terrors: as the weeds bow down before the feverish wind, and the sound of the going in the tops of the taller trees passes on before the clouds, and the fitful opening of pale spaces on the dark water as if some invisible hand were casting dust abroad upon it, gives warning of the anger that is to come, we may well imagine that there is indeed a fear passing upon the grass, and leaves, and waters, at the presence of some great spirit commissioned to let the tempest loose; but the terror passes, and their sweet rest is perpetually restored to the pastures and the waves. Not so to the mountains. They, which at first seem strengthened beyond the dread of any violence or change, are yet also ordained to bear upon them the symbol of a perpetual Fear: the tremor which fades from the soft lake and gliding river is sealed, to all eternity, upon the rock; and while things that pass visibly from birth to death may sometimes forget their feebleness, the mountains are made to possess a perpetual memorial of their infancy,—that infancy which the prophet saw in his vision: "I beheld the earth, and lo, it was without form and void, and the heavens, and they had no light. I beheld the mountains, and lo, they trembled; and all the hills moved lightly."
§ 7. Thus far may we trace the apparent typical signification of the structure of those noble rocks. The material uses of this structure are not less important. These substances of the Serviceable characters of the Slaty Crystallines.
1. Fitness for building with. higher mountains, it is always to be remembered, were to be so hard as to enable them to be raised into, and remain in, the most magnificent forms; and this hardness renders it a matter of great difficulty for the peasant to break them into such masses as are required for his daily purposes. He is compelled in general to gather the fragments which are to form the walls of his house or his garden from the ruins into which the mountain suffers its ridges to be naturally broken; and if these pieces were absolutely irregular in shape, it would be a matter of much labor and skill to build securely with them. But the flattened arrangement of the layers of mica always causes the rock to break into flattish fragments, requiring hardly any pains in the placing them so as to lie securely in a wall, and furnishing light, broad, and unflawed pieces to serve for slates upon the roof; for fences, when set edgeways into the ground; or for pavements, when laid flat.
§ 8. Farther: whenever rocks break into utterly irregular fragments, the masses of débris which they form are not only excessively difficult to walk over, but the pieces touch each other in 2. Stability in débris. so few points, and suffer the water to run so easily and so far through their cavities, that it takes a long series of years to enable them either to settle themselves firmly, or receive the smallest covering of vegetation. Where the substance of the stone is soft, it may soon be worn down, so that the irregular form is of less consequence. But in the hard crystallines, unless they had a tendency to break into flattish fragments, their ruin would remain for centuries in impassable desolation. The flat shape of the separate pieces prevents this; it permits—almost necessitates—their fitting into and over each other in a tolerably close mass, and thus they become comparatively easy to the foot, less permeable to water, and therefore retentive both of surface moisture and of the seeds of vegetation.
§ 9. There is another result of nearly equal importance as far as regards the habitableness of the hills. When stones are thrown together in rounded or massy blocks, like a heap of hazel 3. Security on declivities. nuts, small force will sometimes disturb their balance; and when once set in motion, a square-built and heavy fragment will thunder down even a slightly sloping declivity, with an impetus as unlikely to be arrested as fatal in its increase. But when stones lie flatly, as dead leaves lie, it is not easy to tilt any one of them upon its edge, so as to set it in motion; and when once moved, it will nearly always slide, not roll, and be stopped by the first obstacle it encounters, catching against it by the edge, or striking into the turf where first it falls, like a hatchet. Were it not for the merciful ordinance that the slaty crystallines should break into thin and flattish fragments, the frequent falls of stones from the hill sides would render many spots among the greater mountain chains utterly uninhabitable, which are now comparatively secure.
§ 10. Of the picturesque aspects which this mode of cleavage produces in the mountains, and in the stones of the foreground, we shall have to speak presently; with regard to the uses of the 4. Tendency to form the loveliest scenery. materials it is only necessary to note farther that these slaty rocks are of course, by their wilful way of breaking, rendered unfit for sculpture, and for nearly all purposes of art; the properties which render them convenient for the peasant in building his cottage, making them unavailable for the architecture of more elaborate edifices. One very great advantage is thus secured for the scenery they compose, namely, that it is rarely broken by quarries. A single quarry will often spoil a whole Alpine landscape; the effect of the lovely bay of the Lago Maggiore, for instance, in which lie the Borromean Islands, is, in great part, destroyed by the scar caused by a quarry of pink granite on its western shore; and the valley of Chamouni itself has lost some of its loveliest rock scenery in consequence of the unfortunate discovery that the boulders which had fallen from its higher pinnacles, and were lying in massy heaps among its pines, were available for stone lintels and door-posts in the building of its new inns. But the slaty crystallines, though sometimes containing valuable mines, are hardly ever quarried for stone; and the scenes they compose retain, in general, little disturbed by man, their aspect of melancholy power, or simple and noble peace. The color of their own mass, when freshly broken, is nearly the same as that of the compact crystallines; but it is far more varied by veins and zones of included minerals, and contains usually more iron, which gives a rich brown or golden color to their exposed sides, so that the coloring of these rocks is the most glowing to be found in the mountain world. They form also soil for vegetation more quickly, and of a more fruitful kind than the granites, and appear, on the whole, intended to unite every character of grandeur and of beauty, and to constitute the loveliest as well as the noblest scenes which the earth ever unfolds to the eyes of men.