76 FROM CENTRAL TIBET TO LADAK.
A couple of kilometers to the north of this second promontory is the low, flat, white island, which we had previously seen from the northern shore. Between the promontory and this island the lake is probably shallow, and the two together form a pretty sharp boundary between the western basin of the Selling-tso and the main body of the lake. Immediately west of the promontory is the mouth of the Alantsangpo, then quite insignificant in appearance, so that its water exercised no visible influence upon the lake water, for even opposite to the river-mouth the latter remained as clear as heretofore.
Hence we bent our faces towards the west, making for the eastern cape of the range which runs south of the Jagju-rapga. Along this stretch I obtained the following soundings — 3.57, 5.02, 7.80, 6.6o, 5. t0, 5.02, and 2.51 m., this last quite close to the cape, where the mountain-slopes descend abruptly into the water. South of this rocky cape there is a bay, not penetrating very deeply inland. The southern flank of the mountains is very much steeper than the northern flank. Continuing our trip towards the west-north-west, quite close to the foot of the range, we obtained soundings of 7.38, 6.60, 5.55, 2.88, 2.42, and 1.65 M. Camp LXXXIII was pitched in the vicinity of Camp LXXVI, but on the left bank of the river, not far from its mouth.
Regarded even as a reconnaissance, this little trip across the Selling-tso was of course far too incomplete to convey any idea of the character of the lake-bottom. The impression which I derived from different parts of the Selling-tso was that the lake is on the whole very shallow. Its position in the midst of an unusually extensive and flat self-contained basin, into which disintegration products have for a long period been accumulating, and laid down, lend support to my inference. It would however be both profitable and interesting to carry through an accurate sounding of this one of the largest salt lakes in Tibet. But for that purpose it would be necessary to have a reliable boat; such a large sheet of water in such a stormy country as that is not to be traversed without danger. If this lake becomes entirely frozen over during the winter, as I am inclined to think it does, because of its relatively slight degree of salinity and its inconsiderable depth, a sounding expedition would be attended with far less difficulty if undertaken at that season. The western bay, which is relatively sheltered, and into which the Jagju-rapga pours all the year round a large quantity of fresh water, may pretty safely be assumed to be frozen hard, for there will always be an appreciable layer of fresh water swimming upon the salt water.* Grenard tells us, that the northern part of the lake was frozen when he travelled along it on that shore (see below). With regard to the shape of the lake, we are now in a position to draw its outline, at all events roughly. I have myself mapped the greater part of the northern and the whole of the western shore, as well as a small part of the southern; while Bower has traversed the rest of the southern shore and Littledale the eastern. Both English travellers kept however at too great a distance from the water's edge to
* In this western bay and a good long way out into the lake there were immense quantities of a small Crustacean, which Prof. W. Leche identifies with the species which G. O. Sars has named and described as Daphniopsis Tibetana (vide vol. VI, Part I, p. 67). In some places the lake waters even at a distance, assumed a deeper tint owing to the presence of these animalculæ.
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