86 MY FIRST JOURNEY IN NORTH—EASTERN TIBET.
of the loose superimposed detritus the clay-slate is everywhere folded outwards. One such place is shown in the accompanying sketch (fig. 69), on the left side of the glen, where the heads of the outcropping strata have been bent into a horizontal position. Other varieties of rock, especially granite and a hard black rock, occur amongst the débris in the watercourses. The vicinity of the glaciated mass will account for the presence of these rocks, which are not visible anywhere else in the locality.
August 9th. The bluff O on the south shore of the lake, visible from our camp to the S. 55° E., and itself not at all lofty, is continued westwards in a series of low, softly rounded crests, the southern mountain-border of the latitudinal valley. The task of surmounting these chains was quite easy, for in point of altitude they were but trifling as compared with the numerous ranges that we had already crossed. Nevertheless this region proved to be an extremely difficult one to travel in. Close beside the lake the ground is practically level, and thence it ascends gently towards the foot of the mountains, being furrowed by numerous small brooks that issue from the snow-field on the mountain-mass O. The surface was excessively soft and marshy, and forced us repeatedly to turn back and make detours, for it refused to bear the weight of our horses and camels. The lower parts of the slopes were strewn with chips of dark schist, resting upon an underlying formation of yellow saturated clay ooze. Here the surface was in a measure firm enough to bear us, and the distance up to the summit appeared but short. Yet the higher we ascended the softer grew the ground. There was not a scrap of hard rock to be seen; the slope consisted entirely of rounded ridges and offshoots of the main range, between which the rivulets flowed down towards the north-west. The western water-divide is situated therefore not far from the shore of the lake. We were making our way up on a ridge between two of these brooks. But the surface soon became so soft that our animals dropped in up to the knees. We who were on foot made stepping-stones of the loose flakes of schist scattered over the ground, or rather tried to do so, but they too sank into the yellow ooze, leaving holes full of water where they disappeared. We could hear the water bubbling, gurgling, and trickling along underneath the débris. It was like walking over subterranean rivers and brooks, which every moment threatened to engulf the caravan. In fact, I marvelled that the entire mountain-side did not, through its own sheer weight, spread itself out thin like a quaking viscous porridge. The only time when it would be possible to travel in this region would be in winter, when the flanks of the mountains become frozen. In a few places, where the flakes of schist stood on edge, the ground bore rather better ; but in the broad shallow torrents, in which there were occasionally small pools of water, it was utterly impossible to advance; in one such place we nearly lost a couple of horses. Some of the men whom I sent to the top of the range to reconnoitre reported, that this was not the only crest, but that there was a whole series of similar ones farther south, all evidently consisting of the same soft and treacherous formation, and all streaked with patches of snow, which by melting only made the surface still softer and more boggy than before. In a word it was about the most hateful conformation that it would be possible to find anywhere on the earth, and it, even more than the attenuated atmosphere, made havoc with the strength of the caravan animals. One naturally inquires how these mountain quagmires originate. Well, they
IIIFカラー高解像度
