§ 19. The next point of importance in these beds is the curvature, to which, as well as to fracture, they seem to have been subjected. This curvature is not to be confounded with that rippling or undulating character of every portion of the slaty crystalline rocks above described. I am now speaking of all kinds of rocks indifferently;—not of their appearance in small pieces, but of their great contours in masses, thousands of feet thick. And it is almost universally true of these masses that they do not merely lie in flat superposition one over another, as the books in [Fig. 8]; but they lie in waves, more or less vast and sweeping according to the scale of the country, as in [Fig. 15], where the distance from one side of the figure to the other is supposed to be four or five leagues.

§ 20. Now, observe, if the precipices which we have just been describing had been broken when their substance was in a hard state, there appears no reason why any connexion should be apparent between the energy of undulation and these broken rocks. If the continuous waves were caused by convulsive movements of the earth's surface while its substance was pliable, and were left in repose for so long a period as to become perfectly hard before they were broken into cliffs, there seems no reason why the second series of shocks should so closely have confined itself to the locality which had suffered the first, that the most abrupt precipices should always be associated with the wildest waves. We might have expected that sometimes we should have had noble cliffs raised where the waves had been slight; and sometimes low and slight fractures where the waves had been violent. But this is not so. The contortions and fractures bear always such relation to each other as appears positively to imply contemporaneous formation. Through all the lowland districts of the world the average contour of the waves of rock is somewhat as represented in [Fig. 16] a, and the little cliffs or hills formed at the edges of the beds (whether by fracture, or, as oftener happens in such countries, by gradual washing away under the surge of ancient seas) are no higher, in proportion to the extent of surface, than the little steps seen in the centre of the figure. Such is the nature, and such the scale, of the ranges of hills which form our own downs and wolds, and the French coteaux beside their winding rivers. But as we approach the hill countries, the undulation becomes more marked, and the crags more bold; so that almost any portion of such mountain ranges as the Jura or the Vosges will present itself under conditions such as those at b, the precipices at the edges being bolder in exact proportion to the violence of wave. And, finally, in the central and noblest chains the undulation becomes literally contortion; the beds occur in such positions as those at c, and the precipices are bold and terrific in exact proportion to this exaggerated and tremendous contortion.

Fig. 16.

§ 21. These facts appear to be just as contrary to the supposition of the mountains having been formed while the rocks were hard, as the considerations adduced in § 15 are to that of their being formed while they were soft. And I believe the more the reader revolves the subject in his thoughts, and the more opportunities he has of examining the existing facts, the less explicable those facts will become to him, and the more reverent will be his acknowledgment of the presence of the cloud.

For, as he examines more clearly the structure of the great mountain ranges, he will find that though invariably the boldest forms are associated with the most violent contortions, they sometimes follow the contortions, and sometimes appear entirely independent of them. For instance, in crossing the pass of the Tête Noire, if the traveller defers his journey till near the afternoon, so that from the top of the pass he may see the great limestone mountain in the Valais, called the Dent de Morcles, under the full evening light, he will observe that its peaks are hewn out of a group of contorted beds, as shown in Fig. 4, [Plate 29]. The wild and irregular zigzag of the beds, which traverse the face of the cliff with the irregularity of a flash of lightning, has apparently not the slightest influence on the outline of the peak. It has been carved out of the mass, with no reference whatever to the interior structure. In like manner, as we shall see hereafter, the most wonderful peak in the whole range of the Alps seems to have been cut out of a series of nearly horizontal beds, as a square pillar of hay is cut out of a half-consumed haystack. And yet, on the other hand, we meet perpetually with instances in which the curves of the beds have in great part directed the shape of the whole mass of mountain. The gorge which leads from the village of Ardon, in the Valais, up to the root of the Diablerets, runs between two ranges of limestone hills, of which the rude contour is given in [Fig. 17], page 154. The great slope seen on the left, rising about seven thousand feet above the ravine, is nothing but the back of one sheet of limestone, whose broken edge forms the first cliff at the top, a height of about six hundred feet, the second cliff being the edge of another bed emergent beneath it, and the slope beyond, the surface of a third. These beds of limestone all descend at a uniform inclination into the gorge, where they are snapped short off, the torrent cutting its way along the cleft, while the beds rise on the other side in a huge contorted wave, forming the ridge of mountains on the right,—a chain about seven miles in length, and from five thousand to six thousand feet in height. The actual order of the beds is seen in [Fig. 18], and it is one of the boldest and clearest examples of the form of mountains being correspondent to the curves of beds which I have ever seen; it also exhibits a condition of the summits which is of constant occurrence in stratified hills, and peculiarly important as giving rise to the serrated structure, rendered classical by the Spaniards in their universal term for mountain ridges, Sierra, and obtaining for one of the most important members of the Comasque chain of Alps its well known Italian name—Il Resegone. Such mountains are not merely successions of irregular peaks, more or less resembling the edge of a much-hacked sword; they are orderly successions of teeth set in one direction, closely resembling those of a somewhat overworn saw, and nearly always produced by successive beds emerging one from beneath the other.

Fig. 18.Fig. 17.

§ 22. In all such cases there is an infinitely greater difficulty in accounting for the forms than in explaining the fracture of a single bed. How, and when, and where, were the other portions carried away? Was each bed once continuous over a much larger space from the point where its edge is now broken off, or have such beds slipped back into some gulf behind them? It is very easy for geologists to speak generally of elevation and convulsion, but very difficult to explain what sort of convulsion it could be which passed forward from the edge of one bed to the edge of another, and broke the required portion off each without disturbing the rest. Try the experiment in the simplest way: put half a dozen of hard captain's biscuits in a sloping position on a table, and then try, as they lie, to break the edge of each, one by one, without disturbing the rest. At least, you will have to raise the edge before you can break it; to put your hand underneath, between it and the next biscuit, before you can get any purchase on it. What force was it that put its fingers between one bed of limestone 600 feet thick and the next beneath? If you try to break the biscuits by a blow from above, observe the necessary force of your blow, and then conceive, if you can, the sort of hammer that was required to break the 600 feet of rock through in the same way. But, also, you will, ten to one, break two biscuits at the same time. Now, in these serrated formations, two biscuits are never broken at the same time. There is no appearance of the slightest jar having taken place affecting the bed beneath. If there be, a huge cliff or gorge is formed at that spot, not a sierra. Thus, in [Fig. 18], the beds are affected throughout their united body by the shock which formed the ravine at a; but they are broken, one by one, into the cliffs at b and c. Sometimes one is tempted to think that they must have been slipped back, one from off the other; but there is never any appearance of friction having taken place on their exposed surfaces; in the plurality of instances their continuance or rise from their roots in waves (see [Fig. 16] above) renders the thing utterly impossible; and in the few instances which have been known of such action actually taking place (which have always been on a small scale), the sliding bed has been torn into a thousand fragments almost as soon as it began to move.[51]

§ 23. And, finally, supposing a force found capable of breaking these beds in the manner required, what force was it that carried the fragments away? How were the gigantic fields of shattered marble conveyed from the ledges which were to remain exposed? No signs of violence are found on these ledges; what marks there are, the rain and natural decay have softly traced through a long series of years. Those very time-marks may have indeed effaced mere superficial appearances of convulsion; but could they have effaced all evidence of the action of such floods as would have been necessary to carry bodily away the whole ruin of a block of marble leagues in length and breadth, and a quarter of a mile thick? Ponder over the intense marvellousness of this. The bed at c ([Fig. 18]) must first be broken through the midst of it into a sharp precipice, without at all disturbing it elsewhere; and then all of it beyond c is to be broken up, and carried perfectly away, without disturbing or wearing down the face of the cliff at c.

And yet no trace of the means by which all this was effected is left. The rock stands forth in its white and rugged mystery, as if its peak had been born out of the blue sky. The strength that raised it, and the sea that wrought upon it, have passed away, and left no sign; and we have no words wherein to describe their departure, no thoughts to form about their action, than those of the perpetual and unsatisfied interrogation,—