of mud delta, which the water flows over, and below that again the arms reunite into one common bed before entering the lake. There are also various salt pools on the east side of this river, which flows, at any rate in its lower part, towards the north-east. When first we caught sight of this stream, we greeted it joyfully, because for two days our caravan animals had had nothing to drink. I hardly expected to find these mountainous regions so poorly supplied with water, especially now that the rainy season had fairly begun, and yet we had marched two entire days without finding so much as a single drinkable pool. The reason of this must be that the loose, pulverised, disintegrated matter absorbs the water, so that it is unable to give rise to running brooks; besides which, in this valley the mountains on both north and south stand a great distance away. The only place where we found water was in the vicinity of the salt lake (alt. 4972 m.), namely in the lake itself, in the pools, and in the river, but the water in all these was heavily charged with salt. The earth in all that neighbourhood must consequently be strongly impregnated with salt. If my observations in central and western Tibet will permit of application here, then I should venture to suggest, that this lake was formerly much more extensive than it is now, and possibly the numerous pools beside it were once integral parts of the lake itself. From the extraordinarily slight fall in the lower part of the river, I should say even a very slight rise in the level of the lake would be followed by a considerable increase in its area, in which it would again incorporate several of the pools and the whole of the lower part of the river. When however the lake shrunk to its present contracted area, it left all round it a ring of saline deposits of varying breadth, but these in consequence of the conjoint activity of disintegration, erosion, and sedimentation have subsequently become covered with a layer of powdery earth. And as the lower part of the river has to cross over this former portion of the lake bottom, it is inevitable that its water should become as bitterly salt as we found it to be. This explanation of the salinity of the river appears to me now to be more probable than that which I noted down on the spot. I then fancied that, as the level of the river at the ford is only a shade higher than the level of the lake, if some other stream, originating after a violent local rain farther east, were to enter the lake at its eastern end, it might chance to raise the lake level sufficiently to drive the lake water up into the river which we had forded.
After leaving the last of the salt pools behind us, we crossed over yet another series of ridges, though these were less rugged than those around the lake. By this we had, it was evident, passed beyond the saline area of the lake, and then after climbing a little towards the south-east we at length hit upon a small freshwater spring in a ravine. The scenery continued to wear the same aspect all the way to Camp XXXVI, at an altitude of 5057 m. Grass was exceedingly sparse, but there was japkak. Skulls and other skeletal parts of kulans and orongo antelopes were extraordinarily numerous in this region; bleached and rotting bones littered every dry watercourse amongst the ridges. They conveyed the impression that the animals had deliberately sought out this desolate region in order to be able to die in peace; it is quite out of the question that all these bones should be the result of excursions by Tibetan hunters, for not only are they scattered about everywhere,
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