IIIFカラー高解像度
国立情報学研究所 - ディジタル・シルクロード・プロジェクト
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| IIIFカラー高解像度 |
| Scientific Results of a Journey in Central Asia, 1899-1902 : vol.3 | |
| 1899-1902年の中央アジア旅行における科学的成果 : vol.3 |
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引用情報
FIRST STAGES ACROSS THE TIBETAN PLATEAU. 461
The schor-like, saliferous strip of shore, which, besides being absolutely barren, shows by its level smoothness that it must formerly have been under water, is a proof that the lake itself is shrinking; for there exist not the slightest grounds for believing that at different seasons the level fluctuates to such a remarkable extent as the amount of shore now exposed would indicate. We are precluded from making any such assumption by the simple fact, that, if such were the case, the lake ought at precisely this season, July, to have been at its highest, because it would have received not only the thaw-water from the snow that may have fallen during the winter on the neighbouring mountains, but also any moisture that may have been locked up in the ground itself by the frost. On the other hand an active evaporation goes on over the lake during the summer; but this factor again is in no slight degree counterbalanced by the circumstance, that a lake which is so salt as this will not freeze even in the severest cold, any more than the Usun-schor does. I do not of course mean to assert that fluctuations of level do not take place; but such as they are, they must be restricted to rather narrow limits. On the whole therefore the lake would at the present time appear to be pretty constant. But if we take note of its level over a relatively long period in the past, then it is pretty certainly shrinking, and its salt-impregnated strip of shore will grow steadily broader during the course of the centuries. Indeed one may venture to predict, that if the lake continues to develop in the future along the lines by which it has moved in the past it will in due time disappear altogether, leaving nothing but a salt-pan behind, of precisely the same character as the many salt basins that we shall soon meet with in middle and western Tibet.
Fig. 357.
Fig. 358.
In the next mountain-range we saw a gap to the S. 20° E. ; but we found it impossible to steer straight towards it, because the hills on the east side of the lake are traversed by a vast number of eroded watercourses, which made marching very difficult, for we had to cross over them all transversly. These hills are arranged in narrow, greatly rounded ridges, consisting of gravel and sand, hard and firm, and completely barren on the surface. In the larger watercourse that comes down from the pass there was at this time no water, though a little distance away we saw a couple of small pit-like pools (fig. 357 and 358), not more than one or two meters in diameter, and filled with foul water, though it was not salt. In a well which we dug
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