THE FIRST VIEW OF DUMBOK-TSO. 163
Lamlung -la we had brownish grey quartzitic sandstone or quartzite. On the slopes, down to the camp, the living rock consisted of dark grey phyllitic argillaceous schist.
A short distance above Tomo-shapko, the springs and frozen swamps come to an end; the springs situated highest up in the valley were the most abundant and formed very extensive ice-sheets. Here two nianis have been built, the biggest being 7 m. in length. The valley there is dry, even without ice. The ground is hard, covered with fine gravel, and partly free from rabbits' holes. The hills on both sides are rounded soft ramifications from the range, and hard rock is seldom seen. Most of the side valleys are small and short, only two or three reaching far into the range. The bed of the principal watercourse in the valley is very shallow, only 5 or 1 o m. broad, and its erosion terraces are not much worked out by running water. As a rule there are no signs of energetic water action, though it seems that a great deal of water ought to come down after heavy rains. But perhaps the greater part sinks into the ground, and lower down, reappears in form of the extensive springs and swamps we had passed.
At the point where the valleys from Gurtse-la and Lamlung- la meet, two tents and several sheepfolds were passed. Our guide took us to the latter valley, though the Gurtse-la road, which had been recommended by the Tibetans of Sumja, probably would have been both easier and shorter. On the eastern road we had the opportunity to discover the depression of Dumbok-tso; on the western road we would perhaps have discovered some other depression. Still we had nothing to complain of, for the road taken proved to be interesting.
Ascending at a moderate rate, we suddenly found ourselves on the flat platform of Lamlung-la; there is no sign of a road and no cairn, which made it still more likely that the most frequented road goes past Gurtse-la. There is no distant view at all from this pass, as it is hidden by rounded hills in the immediate vicinity, as shown on Pan. i oo, Tab. 17. The valley that goes down on the other side, to the S. 55° E., is rather narrow and very steep, and we preferred to continue to the S. E. across the hills, thus reaching a second flat pass of the same height as Lamlung-la and being of secondary importance. From here the view was both surprising and interesting. It is seen on Pan. I 1 1, Tab. 2 0. From N. 15 ° E. to S. 1o° E., there is a semi-circle of considerable mountains, among which the Chag-a lung-nak Peaks to the E. N. E., are the highest. Inside this ring of mountains is a depression, to the western edge of which our hills fall steeply down with their gravelly slopes, finally forming a barren plain of gravel, across which several dry watercourses wind their way down to a little lake called Dumbok-tso. In the middle of the depression there is a little isolated ridge, rocky and picturesquely modelled by weathering and erosion. Its name is Tso-ri, or the »mount of the lake». To the S. W., from Tso-ri, a neck of land connects the isolated mount with the last ramifications from
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