国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

THE THIRD CROSSING.

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its water has not yet become salt; it is surprising that no sign of an outlet was visible; but there may be an underground one.

Along the southern shore of the lake there is a good deal of alga where wild geese and ducks are very numerous. From the eastern and southern shore one gets the impression that the mountains at the western shore slope steep down into the lake, but probably there is a flat strip of land between the lake and the foot of the mountains. These western mountains, which I have called the Shuru range, and which have been mentioned above under the name of Do, belong to the highest and most magnificent in this part of Tibet, although there are no particularly high peaks, only a great number of pyramidal summits covered with snow. It will be a beautiful and important object for future exploration to examine this range and its probable connection with the Targo-gangri.

The consistency of the ice did not allow me to measure the depth of Shurutso. Only near the shore could some spots be examined. In the southernmost part of the lake the depth was 16 m a short distance N.E. of the mouth of the Tagelung-tsangpo; a series of soundings gave II, 8, I2, 8, 6, 3 and 2 m, along the edge of the ice which filled the middle of the lake. Probably the lake is deep in the middle. Meridional lakes in Tibet must, as a rule, be deeper than latitudinal; such must be the case especially with those lakes which have high mountains on their shores, such as Shuru-tso and Dangra-yum-tso. The Ngangtse-tso, on the other hand, being latitudinal, has only Io m as a maximum depth. An indication of considerable depth in the Shuru-tso are also the old beach-lines at a short distance from the present shore of the southern part of the lake. Near the mouth of the Tagelungtsangpo the highest visible shore-line was 43,5 m above the present level of the lake. As the highest measured shore-line of Dangra-yum-tso is at an absolute height of 4 798 m, there must be higher beach-lines round the Shuru-tso above that of 43,5 , which, however, was the highest one visible at the southern end of the lake.

The sources of the Tagelung-tsangpo are said to be situated at two days' journey S. 400 E. in the high range of Angden-la and Sha-la. Quite close to its mouth, another river, Tsargam-tsangpo, coming from the S.S.W., enters the lake. Where it enters the lake the flat shore plain is comparatively broad, but becomes narrower to

the N.W., and at some places the slopes seem to reach the very edge of the water. Instead of following the course of the Tsargam river, the road turns S.W.

amongst hills which are the last undulations of the high western mountains.

Several affluents to the Tsargam descend from them. One of them, Otsuk, has cut a deep valley at the S.W. foot of the little threshold Dunka-la. The next tributary is Amlung, in the background of which are seen snow- and ice-mountains. Then follow Gabrup, Serchung and Serchen, separated from each other by lower, rocky ridges. All these tributaries go through a deep cut valley to Tsargam-tsangpo• At this season they had very little or no water. The Tsargam and Tagelung, coming from very high mountains, bring a good deal of water down to Shuru-tso.