off in channels which as a rule are but slightly eroded and practically always terminate in a salt lake. The crests and peaks upon which the precipitation rests in the form of perpetual snow are far rarer on the plateau than is generally believed. In the course of the journey which I have thus far described we have passed but few glaciated mountains and they all rise above the plateau in the form of insular, round flattened domes, while their relative altitudes are not great. These mountain masses are scattered sporadically over the highlands without any connection one with another, but all the same they always constitute the culminating parts of the parallel ranges, and if only we knew them all, and were able to prick their positions on a map, they would form more or less parallel chains of glacial »islands» of the kind I have described. Seeing now that, as happened during the summer of 1900, at all events during the latter part of August, rain falls nearly every day, and often in vast quantities, one is at first amazed at not finding more extensive areas of perpetual snow, and a greater number of glaciated regions, than actually is the case. But then it happens that the summer is just the rainy season, and during the rest of the year little or no snow falls, as we shall find later on. When I have concluded this physical-geographical and morphological account of the important parts of Tibet through which I travelled during this journey, I shall, in a special chapter, return and deal at greater length with this interesting problem, although the data at disposal are unfortunately not sufficient to permit of definitive conclusions.
On August 19th the glacier stream showed us the way down to lower regions, where there was reasonable hope of finding better grazing. The stream had however shrunk considerably; the water, thick with clay, flowed along silently like oil, and yet the velocity was not less than 1.6 cub.m. in the second. At 9 a. m. the water had a temperature of 6.3°. We forded the stream just below the camp, at a point where it is joined by another stream, equally as big as itself and of the same brick-red colour. The latter issues from the western frontal part of the great glacier arm situated in the S. 8o° W. At first we marched down the middle of the channel; the ground there, although wet and muddy, was mingled with gravel, and was hard, the loose material having been packed together firmly by the running water. But after fording the river a certain number of times, we kept for a while to the hills on the left bank. At the last fording the whole of the volume was collected into one channel 28 m. broad. The hills were very low, rounded, and grass-grown; but the brick-red colour predominates everywhere. Here there were a couple of small pools. Opposite to us on the right bank was a small isolated mountain, which plunged steeply down into the bed of the stream and appeared to possess relatively good grazing in its smaller hollows. Here again our stream was joined by another coming from the west, this too as big as itself. The dimensions of our stream were gradually increasing, and when we finally lost sight of it, it was so large that it could not have been forded without difficulty. As a rule it is divided into several arms. At that time only a small portion of the channel was covered with water; but it was nevertheless everywhere wet, showing that quite recently, probably after the last continuous rain, the volume had been very considerable indeed. One branch of the stream flows close in under the isolated mountain I have just spoken of, and there the red sandstone is again exposed in the face of the deeply scarped bank.
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