IIIF Color HighRes
National Institute of Informatics - Digital Silk Road Project
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| IIIF Color HighRes |
| Scientific Results of a Journey in Central Asia, 1899-1902 : vol.4 |
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Citation Information
THE OMAN-TSO, THE 1>ADAP-TSI), AN1) THE PERUTSE-TSO. 20I
The rocks we saw this day were as follows : at the salt pool immediately east of the little pass a dark greenish schist, dipping 51° to the N. 85° E. and seamed with a vein of fresh and beautiful grey granite, at the sides of which the schist was especially hard and assumed an angle of 40° towards the N. 72° E. The same crystalline schist, together with the granite, cropped out also in a small steep side-glen, that comes down from the southern mountains to the lake. The lower part of this little side-glen cuts through certain soft white strata, lying 18° to the N. 3o° W. A specimen which has been examined by Mr. Aminoff turns out to consist for the most part of calcium carbonate with a smaller percentage of gypsum. On the left side of the threshold pass is a rather coarse granite, bedded at 48° to the S. i2° «W.; in it occurred veins of a hard, finely crystalline schist, of a dark-green colour. The flanks of the red mountains are everywhere strewn with fragments of this rock. The same rock occurs again in a little knoll that crops out on the very shore of the Perutse-tso, dipping 74° to the N. i7° E. Fragments as well as blocks of this stone are likewise common in places on the southern shore of
the lake.
During the four days that we spent beside the Perutse-tso the wind blew incessantly from the west, sometimes with hurricane force, driving before it in thick clouds along the ground everything of the nature of loose dust or fragments of dry plants. It was impossible to screen yourself against it: even the bell-shaped yurt which I occupied was not enough; for even when you have your tent-opening to the
leeward, there is always an eddy of dust and sand dancing and whirling up like smoke in front of it.
At this lake wild-geese were numerous, though they were all birds of passage. Indeed they did not even rest on the shores of the Perutse-tso, but kept flying over it, with loud screamings, though only at night. They were evidently on their way from the lowlands of inner Asia to India. As it was a long time since we had seen wild-geese, and as after this we very seldom saw them either, this depression would seem to form one of the great highways which they have no doubt followed in their migrations from time immemorial. It is of course quite reasonable that they should endeavour to fly across the flat parts of the plateau, and, consistently with keeping to as straight a line as possible, should avail themselves of the biggest depressions, for over them the air is relatively less attenuated, and in that way the geese avoid crossing over the tops of the high ranges. They have of course many similar routes; indeed we observed several of their stopping-stations in the lacustrine regions of eastern Tibet and others at the Bacch-kum-köl. How interesting and instructive it would be to have a general map of the whole of Tibet with all the isohypsometrical curves entered on it, and also with the migration tracks of the wild-geese! But the construction of such a map is at present impossible, and indeed it will long
Hedin, Tourney in Central Asia. IV. 26
Fig. 115. LOOKING N 50 E FROM CAMP CXVII; MT NAGBO.
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