the bedded structure in all the instances of mountain form given in the preceding chapter; and must have asked himself, Why are mountains always built in this masonry-like way, rather than in compact masses? Now, it is true that according to present geological theories, the bedded structure was a necessary consequence of the mode in which the materials were accumulated; but it is not less true that this bedded structure is now the principal means of securing the stability of the mass, and is to be regarded as a beneficent appointment, with such special view. That structure compels each mountain to assume the safest contour of which under the given circumstances of upheaval it is capable. If it were all composed of an amorphous mass of

stone as at A, Fig. 19, a crack beginning from the top, as at x in A, might gradually extend downwards in the direction xy in B, until the whole mass, indicated by the shade, separated itself and fell. But when the whole mountain is arranged in beds, as at c, the crack beginning at the top stops in the uppermost bed, or, if it extends to the next, it will be in a different place, and the detached blocks, marked by the shaded portions, are of course still as secure in their positions as before the crack took place. If, indeed, the beds sloped towards the precipice, as at D, the danger would be greater; but if the reader looks to any of the examples of mountain form hitherto given, he will find that the universal tendency of the modes of elevation is to

cause the beds to slope away from the precipice, and to build the whole mountain in the form c, which affords the utmost possible degree of security. Nearly all the mountains which rise immediately above thickly peopled districts, though they may appear to be thrown into isolated peaks, are in reality nothing more than flattish ranks of rock, terminated by walls of cliff, of this perfectly safe kind; and it will be part of our task in the succeeding chapter to examine at some length the modes in which sublime and threatening forms are almost deceptively assumed by arrangements of mountain which are in themselves thus simple and secure.

§ 3. It, however, fell within the purpose of the Great Builder to give, in the highest peaks of mountains, examples of form more strange and majestic than any which could be attained by structures so beneficently adapted to the welfare of the human race. And the admission of other modes of elevation, more terrific and less secure, takes place exactly in proportion to the increasing presence of such conditions in the locality as shall render it on other grounds unlikely to be inhabited, or incapable of being so. Where the soil is rich and the climate soft, the hills are low and safe;* as the ground becomes poorer and the air keener, they rise into forms of more peril and pride; and their utmost terror is shown only where their fragments fall on trackless ice, and the thunder of their ruin can be heard but by the ibex and the eagle.

§ 4. The safety of the lower mountains depends, as has just been observed, on their tendency to divide themselves into beds. But it will easily be understood that, together with security, such a structure involves some monotony of aspect; and that the possibility of a rent like that indicated in the last figure, extending itself without a check, so as to detach some vast portion of the mountain at once, would be a means of obtaining accidental forms of far greater awfulness. We find, accordingly, that the bedded structure is departed from in the central peaks; that

* It may be thought I should have reversed these sentences, and written where the hills are low and safe, the climate is soft, &c. But it is not so. No antecedent reason can be shown why the Mont Cervin or Finsteraarhorn should not have risen sharp out of the plains of Lombardy, instead of out of glaciers.

they are in reality gifted with this power, or, if we choose so to regard it, affected with this weakness, of rending downwards throughout into vertical sheets; and that to this end they are usually composed of that structureless and massive rock which we have characterized by the term "compact crystalline."

§ 5. This, indeed, is not universal. It happens sometimes that toward the centre of great hill ranges ordinary stratified rocks of the coherent groups are hardened into more compact strength than is usual with them; and out of the hardened mass a peak, or range of peaks, is cut as if out of a single block. Thus the well known Dent du Midi of Bex, a mountain of peculiar interest to the English travellers who crowd the various inns and pensions which now glitter along the shores of the Lake of Geneva at Vevay, Clarens, and Montreux, is cut out of horizontal beds of rock which are traceable in the evening light by their dark and light lines along its sides, like courses of masonry; the real form of the mountain being that of the ridge of a steep house-roof, jagged and broken at the top, so that, seen from near St. Maurice, the extremity of the ridge appears a sharp pyramid. The Dent de Morcles, opposite the Dent du Midi, has been already noticed, and is figured in Plate 29, Fig. 4. In like manner, the Matterhorn is cut out of a block of nearly horizontal beds of gneiss. But in all these cases the materials are so hardened and knit together that to all intents and purposes they form one solid mass, and when the forms are to be of the boldest character possible, this solid mass is unstratified, and of compact crystalline rock.

§ 6. In looking from Geneva in the morning light, when Mont Blanc and its companion hills are seen dark against the dawn, almost every traveller must have been struck by the notable range of jagged peaks which bound the horizon immediately to the north-east of Mont Blanc. In ordinary weather they appear a single chain, but if any clouds or mists happen to float into the heart of the group, it divides itself into two ranges, lower and higher, as in Fig. 1, Plate 29, of which the uppermost and more distant chain is the real crest of the Alps, and the lower and darker line is composed of subordinate peaks which form the south side of the valley of Chamouni, and are therefore ordinarily known as the " Aiguilles of Chamouni."