THE WESTERN PANGGONG-TSO. 347
ever; bute there is an open valley connecting the N. W. end of its basin with that of the Tanktse affluent of the Nubra river, via Muglib, the length of dormant drainage between the edge of the lake near Jaktil, and the first appearance of the Muglib rivulet in a scanty spring at Wangtong being 7 or 8 miles; and the spring, being sub-saline, is considered by the Tibetan inhabitants as a filtration of the lake water. The watershed across the head of the valley is almost imperceptible, but lies probaly at Donzho Lhato, only a mile from the lake, and scarce 1 oo feet above its present surface. The present level of the water is about 13,400 feet.
All along the banks of the lake there is a well-defined zone of horizontal watermarks, extending to a height of perhaps 7o feet above the present surface, formed both by calcareous concretions and by erosions on the foot of the marginal rocks, corresponding marks being also visible in parts of the alluvial shore; and the uppermost of these lines no doubt marks the level of the existing watershed at Donzho. The gradual subsidence of the lake is established by further evidence. The plain at Ot, which is raised only 1 o or 12 feet above the present water-line, consists of fine earthy strata full of small shells, which are very perfect and unaltered, if fossils at all of the most recent sort, and some of them closely resembling (if not identical with) a small species still living in the Tso-Rul, though none were observed in the water of the Pangong itself. Although the inhabitants of Pangong have no tradition regarding the origination of Ot by the subsidence of the lake, its gradual desiccation in the present (i. e. human v. historic) era seems probable; and I was informed by a Tibetan, who had visited the lake in company with Moor-croft . in 1821, and again with myself in 1848, that the water had receded perceptibly from the encamping ground at Jaktil during these 27 years, which, as the shore there is flat, might have been done by a very slight subsidence of the water.»*
* Physical Geography of Western Tibet, by Captain H. Strachey, in Journal of the Royal Geographical Society, vol. XXIII, P. 47 (i853).
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