We had still some way to go before we came to the actual source, and I could not conscientiously leave Kubi-gangri without determining the absolute height of the source by the boiling-point thermometer. Our Tibetans were exceedingly friendly, and seemed to take an interest in showing us this point, of which I had spoken so often during the past days and about which I had put so many questions. I was really thankful for, and overjoyed at, this unexpected favourable opportunity of fixing the position of the source, though I knew that my excursion to Kubi-gangri could only be a very cursory and defective reconnaissance. A thorough exploration of this neighbourhood would require several years, for the summer up here is short and the time for work is over in two months. But though I succeeded in learning only the chief outlines of the physical geography, I can count this excursion as one of the most important events of my last journey in Tibet. Accordingly, we decided to ride up to the source next day, July 13. Only Rabsang, Robert, and a Tibetan were to accompany me. The rest were to wait for our return under the command of Tsering.

CHAPTER XLIII

THE SOURCE OF THE SACRED RIVER—A DEPARTURE

We started off in beautiful weather, not a cloud hanging over the summits of Kubi-gangri. We followed the left bank of the Kubi-tsangpo, and rode along the foot of the huge moraines, which here rise fully 470 feet above the valley bottom, and which were formerly thrown up on the left or western side of the gigantic glacier, whence proceeded all the glacier tongues now remaining only in short lengths. The morainic character is plainly recognizable, sometimes in curved ridges and walls falling steeply on both sides, sometimes in rounded hillocks rising one above another. The surface is often covered with fine pebbles, grass, and lovely alpine flowers trying to make the most of the short summer. Here and there a landslip has taken place, and then it can be seen that the rock shows no trace of stratification. Occasionally we pass granite boulders, but they are small, the largest not more than 280 cubic feet. On the valley bottom are swamps with rank grass, and wild-geese are enjoying the summer in the ponds. We twice met with fresh spoor of small herds of wild yaks which had moved off to the right bank of the Kubi-tsangpo. The horses’ hoofs splashed in the swampy ground, seldom varied by small patches of boulder clay.

Numerous rivulets descend from the moraines. They are fed by the melting snowfields, and therefore, in contrast to the glacier brooks, are crystal clear. They have eroded deep valleys in the moraines, and one of them has deposited a great dejection cone at the mouth, over which the brook falls in ten channels, carrying 106 cubic feet of water. A very considerable proportion of the upper Brahmaputra’s water is derived from melted snow. Rivulets rushed and spurted all about in the rubbish, and all came from the snowfields, which struggled in vain against the heat of the spring sun.

Now we have right in front of us the immense glacier which descends from an extensive firn basin on the western foot of the Mukchung-simo massive. Between its terminal moraines and the older moraines we have skirted, a rather voluminous stream has eroded its valley. Its water is tolerably clear and green, so that it proceeds from snowfields. A little below the terminal moraine it unites with the numerous arms of the muddy glacier stream, of which the largest is the one which flows nearest to the foot of the Mukchung massive. Even 200 yards below the confluence the green water can be clearly distinguished from the brown, but afterwards the cold currents intermingle. Where the river, still divided into a number of meandering arms, turns past camp 201 to the north-east, it receives considerable additions from the glaciers lying further east, and thus the Kubi-tsangpo is formed.

Then we ride up, zigzagging among boulders and pebble beds, over ridges, banks, and erosion furrows, over brooks and treacherous bog, over grass and clumps of brushwood, to a commanding point of view on the top of the old moraine (16,453 feet). Before us is a chaos of huge, precipitous, fissured, black, bare rocks, summits, pyramids, columns, domes, and ridges, moraines, tongues of ice, snow and firn fields—a scene hard to beat for wild grandeur.

Here we made a halt, and I drew the panorama while the horses grazed on the slopes. The largest glacier, which comes from the Kubi-gangri proper, is entirely below us, and we have a bird’s-eye view of it. It is fed by three different firn-fields, and has two distinct medial moraines, which here and there rise into ridges where the ice has been thrust aside. The right lateral moraine is well defined, and is still partially covered with snow. The left is broad in its upper part but narrow below, where the green stream washes its base. Up above, a glacier from the west runs into the main glacier, and where the two join the side glacier is thrown up into a mighty wall, which merges into the left lateral moraine of the other. All the bottom of the glacier front is buried in rubbish, and the ice peeps out only here and there. Here are several small sheets of water, some of an intensely blue colour, others brown, with finely pulverized matter, showing that they are connected with the water of the ground moraine. Two of these small pools have vertical sides of blue ice like entrances to marvellous fairy grottos. A series of marginal crevasses are still partly covered with snow. The terminal moraine is a chaos of mounds, pebbles, and boulders, with patches of snow on the shady side. In a hollow between these hillocks flows the middle glacier stream, after passing two pools. The terminal moraine does not increase in size, for its material is slowly disintegrated and washed away by the stream, which winds in several arms over the even bed of the valley bottom just below in the most capricious curves.