into such a form as that at x; and the flakes again subdividing and falling, we should have conditions such as at y. Meanwhile the glacier is still doing its work uninterruptedly on the lower bank, bringing the mountain successively into the outlines c and d, in which the forms x and y are substituted consecutively for the original summit. But the level of the whole flank of the mountain being now so much reduced, the glacier has brought itself by its own work into warmer climate, and has wrought out its own destruction. It would gradually be thinned away, and in many places at last vanish, leaving only the barren rounded mountains, and the tongues of ice still supplied from the peaks above.

§ 18. Such is the actual condition of the Alps at this moment. I do not say that they have in reality undergone any such process. But I think it right to put the supposition before the reader, more with a view of explaining what the appearance of things actually is, than with any wish that he should adopt either this or any other theory on the subject. It facilitates a description of the Brèche de Roland to say, that it looks as if the peer had indeed cut it open with a swordstroke; but it would be unfair to conclude that the describer gravely wished the supposition to be adopted as explanatory of the origin of the ravine. In like manner, the reader who has followed the steps. of the theory I have just offered, will have a clearer conception of the real look and anatomy of the Alps than I could give him by any other means. But he is welcome to accept in seriousness just as much or as little of the theory as he likes.* Only I

* For farther information respecting the glaciers and their probable action, the reader should consult the works of Professor Forbes. I believe this theory of the formation of the upper peaks has been proposed by him, and recently opposed by Mr. Sharpe, who believes that the great bank spoken of in the text was originally a sea-bottom. But I have simply stated in this chapter the results of my own watchings of the Alps; for being without hope of getting time for available examination of the voluminous works on these subjects, I thought it best to read nothing (except Forbes's most important essay on the glaciers, several times quoted in the text), and therefore to give, at all events, the force of independent witness to such impressions as I received from the actual facts; De Saussure, always a faithful recorder of those facts, and my first master in geology, being referred to, occasionally, for information respecting localities I had not been able to examine.

am well persuaded that the more familiar any one becomes with the chain of the Alps, the more, whether voluntarily or not, the idea will force itself upon him of their being mere remnants of large masses,-splinters and fragments, as of a stranded wreck, the greater part of which has been removed by the waves; and the more he will be convinced of the existence of two distinct regions, one, as it were, below the ice, another above it,-one of subjected, the other of emergent rock; the lower worn away by the action of the glaciers and rains, the higher splintering and falling to pieces by natural disintegration.

§ 19. I press, however, neither conjecture nor inquiry farther; having already stated all that is necessary to give the reader a complete idea of the different divisions of mountain form. I proceed now to examine the points of pictorial interest in greater detail; and in order to do so more conveniently, I shall adopt the order, in description, which Nature seems to have adopted in formation; beginning with the mysterious hardness of the central crystallines, and descending to the softer and lower rocks which we see in some degree modified by the slight forces still in operation. We will therefore examine: 1. the pictorial phenomena of the central peaks; 2. those of the summits of the lower mountains round them, to which we shall find it convenient to give the distinguishing name of crests; 3. the formation of Precipices, properly so called; then, the general aspect of the Banks and Slopes, produced by the action of water or of falling débris, on the sides or at the bases of mountains; and finally, remove, if it may be, a few of the undeserved scorns thrown upon our most familiar servants, Stones. To each of these subjects we shall find it necessary to devote a distinct chapter.

RESULTING FORMS-FIRST, AIGUILLES.

§ 1. I HAVE endeavored in the preceding chapters always to keep the glance of the reader on the broad aspect of things, and to separate for him the mountain masses into the most distinctly comprehensible forms. We must now consent to take more pains, and observe more closely.

§ 2. I begin with the Aiguilles. In Fig. 24, p. 170, at a, it was assumed that the mass was raised highest merely where the elevating force was greatest, being of one substance with the bank or cliff below. But it hardly ever is of the same substance. Almost always it is of compact crystallines, and the bank of slaty crystallines; or if it be of slaty crystallines the bank is of slaty coherents. The bank is almost always the softer of the two.*

Is not this very marvellous? Is it not exactly as if the substance had been prepared soft or hard with a sculpturesque view to what had to be done with it; soft, for the glacier to mould, and the torrent to divide; hard, to stand for ever, central in mountain majesty.

§ 3. Next, then, comes the question, How do these compact crystallines and slaty crystal

lines join each other? It has

FIG. 25.

long been a well recognized fact in the science of geology, that the most important mountain ranges lift up and sustain upon their sides the beds of rock which form the inferior groups of hills around them in the manner roughly shown in the section Fig. 25, where the dark mass stands for the hard rock of the great

* See, for explanatory statements, Appendix 2.

mountains (crystallines), and the lighter lines at the side of it indicate the prevalent direction of the beds in the neighboring hills (coherents), while the spotted portions represent the gravel and sand of which the great plains are usually composed. But it has not been so universally recognized, though long ago pointed out by De Saussure, that the great central groups are often themselves composed of beds lying in a precisely opposite direction; so that if we analyze carefully the structure of the dark mass in the centre of Fig. 25, we shall find it arranged in lines which slope downwards to the centre; the flanks of it being of slaty crystalline rock, and the summit of compact crystallines, as at a, Fig. 26.

In speaking of the sculpture of the central peaks in the last chapter, I made no reference to the nature of the rocks in the banks on which they stood. The diagram at a, Fig. 27, as representative of the original condition, and b, of the resultant condition will, compared with Fig. 24, p. 170, more completely illustrate the change.*

§ 4. By what secondary laws this structure may ultimately be discovered to have been produced is of no consequence to us at present; all that it is needful for us to note is the beneficence

* I have been able to examine these conditions with much care in the chain of Mont Blanc only, which I chose for the subject of investigation both as being the most interesting to the general traveller, and as being the only range of the central mountains which had been much painted by Turner. But I believe the singular arrangements of beds which take place in this chain have been found by the German geologists to prevail also in the highest peaks of the Western Alps; and there are a peculiar beauty and providence in them which induce me to expect that farther inquiries may justify our attributing them to some very extensive law of the earth's structure. See the notes from De Saussure in Appendix 2.

a

which appointed it for the mountains destined to assume the boldest forms. For into whatever outline they may be sculptured by violence or time, it is evident at a glance that their stability and security must always be the greatest possible under the given circumstances. Suppose, for instance, that the peak is in such a form as a in Fig. 26, then, however steep the slope may be on either side, there is still no chance of one piece of rock sliding off another; but if the same outline were given to beds disposed as at b, the unsupported masses might slide. off those beneath them at any moment, unless prevented by the inequalities of the surfaces. Farther, in the minor divi

FIG. 27.

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sions of the outline, the tendency of the peak at a will be always to assume contours like those at a in Fig. 28, which are, of course, perfectly safe; but the tendency of the beds at b in Fig. 27 will be to break into contours such as at b here, which are all perilous, not only in the chance of each several portion giving way, but in the manner in which they would deliver, from one to the other,

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b

FIG. 28.

the fragments which fell. A stone detached from any portion of the peak at a would be caught and stopped on the ledge beneath it; but a fragment loosened from b would not stay till it reached the valley by a series of accelerating bounds.

§ 5. While, however, the secure and noble form represented