I20 MY FIRST JOURNEY IN NORTH-EASTERN TIBET.
That day we only saw hard rock twice, and it barely projected above the ground, which consisted of soft disintegrated material. The rock was black crystalline schist, belonging to a ridge south-west of the lake, and dipping 56° towards the S. 50° E. and 54° towards the S. 6o° E. All the gravel we saw consisted of the same material.
During the two following afternoons and evenings it rained with extraordinary smartness, so that by the 27th August the ground in the bare, barren places was again soft and miry. As a rule however it still continued to be grassy, and consequently bore us. The rain caused the brook south of our camp to swell, and its water turned a muddy red colour. It was 17 m. broad, had a mean velocity of 0.3 m., a mean depth of 0.4 m. and a maximum depth of 0.6 m., and a volume of 2 cub.m. in the second. It appeared to issue from the mountain-group G', which rose to the S. 70° W. So far as we were able to see for the hills, the brook continued on towards the east, and it hardly seems possible that it can be connected with the two rather large pools which lie to the south of it, or can even touch them, because they are of a bright blue colour, whereas the stream was, as I have said, muddy. Probably the brook makes its way to the next salt lake to the south. The more westerly pool of the two is entered by a small brook from that same direction, and apparently it continues as far as the eastern pool.
South of these two pools the country again rises to a low swelling, from the top of which we obtained as usual a view of the next salt lake, inclosed between two series of low heights. Those on the south-east were so low, that we caught glimpses of yet other sheets of water gleaming beyond them. But on the south of them was a pretty considerable mountain-range, forming the boundary of the lake-basin on that side. Close to the shore we passed yet another large pool, likewise entered by a little brook from the west; its semi-transparent water had a temperature of 200.3, and yet the sun had not shown himself that day and the night had been frosty. Probably the pool is fed by relatively warm springs. At the point where we forded it, its bed was completely sterile, but contained an abundance of the same small Crustaceans that we had already met with in several places before, and which are described in another part of this work.* Between the pool and the lake the ground is for the most part barren, being clothed with only a thin sprinkling of moss. Otherwise it is strewn with gravel, and was often marshy.
The western shore of this lake is more irregular than usual, being diversified by a couple of long capes, several small islands, and one large island of a curious annular form, and only just rising above the water. Strange to say this lake, notwithstanding that it seems to mark a low depression in a fresh latitudinal valley, is not entered by any main stream from the west. Instead of that it is joined by several small rivulets from that direction. Probably the reason is that the country west of the lake does not possess an evenly distributed slope towards the east, but is on the whole horizontal, and is divided up into a mosaic of small basins, each containing a pool of the same kind as those which we had just left behind us.
Grass began to make its appearance again on the hills of the western shore, and between the south-western corner of the lake and an elongated pool the grazing
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