We were impressed anew by the abnormal and manifold cleavages of the granite. It was like climbing amid the overthrown and fire-blasted blocks of a Titan citadel. Everywhere the slope was rent into huge, obliquely angled masses, often partly vitrified, which made the ascent a more arduous problem than we had expected. Plainly, at some former time, the stone had been subjected to the action of heat; and yet there were no volcanic craters amid the nearby mountains. Puzzling greatly, I recalled a passage in the old volume, hinting ambiguously at the dark fate that had long ago destroyed the city's inhabitants. But from this passage I could still draw no definite conclusion: for the ideation was too fantastic to be understood as anything more than a dubious figure of speech. We had left our three llamas at the slope's bottom, merely taking with us provisions for a night. Thus unhampered, we made fair progress in spite of the ever-varying obstacles offered by the shattered scarps. After a while we came to the hewn steps of a stairway mounting to the summit; but the steps had been wrought for the feet of colossi, and, in many places, they were part of the heaved and tilted ruin; so they did not greatly facilitate our climbing. The sun was still high above the western pass behind us; and for this reason, as we went on, I was much surprised by a sudden deepening of the char-like blackness on the rocks. Turning, I saw that several greyish vapory masses, which might have been either cloud or smoke, were drifting idly about the summits that overlooked the pass; and one of these masses rearing like a limbless figure, upright and colossal, had interposed itself between us and the sun. Sebastian and the guide had also noted this phenomenon. Clouds were almost unheard-of amid those mountains in summer; and the presence of smoke would have been equally hard to explain. Moreover, the grey masses were wholly detached from each other and showed a peculiar opacity and sharpness of outline. At second glance they did not really resemble any cloud forms we had ever seen; for about them there was a baffling suggestion of weight and solidity. Moving sluggishly into the heavens above the pass, they preserved their original contours and their separateness. They seemed to swell and tower, coming toward us on the blue air from which, as yet, no lightest stirring of wind had reached us. Floating thus, they maintained the rectitude of massive columns or of giants marching on a broad plain. I think we all felt an alarm that was none the less urgent for its vagueness. Somehow, from that instant, it seemed that we were penned up by unknown powers and were cut off from all possibility of retreat. We had ventured into a place of hidden peril--and the peril was upon us. In the movement of the strange clouds there was something alert, deliberate--and implacable. Polder spoke with a sort of horror in his voice, uttering the thought which had already occurred to me.