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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| Scientific Results of a Journey in Central Asia, 1899-1902 : vol.2 | |
| 1899-1902年の中央アジア旅行における科学的成果 : vol.2 |
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引用情報
THE WATERS ON THE NORTH OF THE KARA-KOSCHUN. 183
the margins of the water young tamarisks a year old were growing up. Their seeds had no doubt been brought there originally by the water, and were now shooting up after being moistened afresh. The köuruk plants had however nothing to do with the water, for they were dotted about at a considerable distance from it. As compared with this quarter, the eastern part of the Desert of Lop which we had just crossed was a perfectly sterile region.
For a considerable distance we travelled north-east beside this irregular sheet of water. In the narrower passages it moved with a pretty lively current, and even in the expansions its movement was distinctly perceptible. In the channel which had stopped our progress, the flow was towards the south; here it was towards the northeast. Along the line on which I surveyed the desert, we had ascertained during the
last few days that there was a slight fall southwards; but here, not especially far west of that line, the slope was towards the north-east. That is to say, the level of the Kara-koschun was at that time somewhat higher than the portion of the desert that lay to the north of it.
At length we came to an absolutely barren neighbourhood. The last lake
with the schor islands sent off a small emissary, . only i 5 to 20 m. long, and that issued into yet another lake, which in its turn extended north-east. Thus one shallow depression after the other was being filled: as soon as the water lipped the edge of the threshold on the north-east, it broke over, formed a new canal-arm, and sought out a fresh basin to fill; and in this way this narrow offshoot from the Kara-koschun kept pushing farther and farther towards the north-east.
The canal had a breadth of 7.2 m., a mean depth of 0.32 m., and a mean
velocity of 1.02 m. in the second; so that the volume amounted to 2.35 cub.m. in the second, or 203,000 cub.m. in the 24 hours, this being the mass of water that was being drained out of Prschevalskij's Kara-koschun by this one arm alone. This was just the season, and especially a few days later when the water from the melting ice would begin to enter the marsh, that these offshoots would swell and flow away to the north; indeed there was no other way they could go. No doubt the pioneer water that arrives first is used up in moistening the schor ground, and it is not until, dry and thirsty as it is, it has become consolidated, that the channel is able to continue its progress; meanwhile the southern basins of the Kara-koschun go on filling higher and higher. Of course vast quantities of water are lost through evaporation in the dry and barren desert. On the whole the ground here is, so far as one can see, perfectly level schor. But the presence of the little current we were following proved, that even this flat schor region had its irregular surface-furrowings, and that they ran parallel to the jardangs and their intermediate gullies in the northern part of the Desert of Lop. This is also no doubt an effect of the wind; and we found that this same south-west to north-east direction characterised all the offshoots of the western Kara-koschun.
The bottom of the 7.2 m. broad channel consisted here of blue clay, as slip-
pery as ice on the surface, but quite firm enough to bear us, so that we should easily have been able to cross it with camels. The water had washed away the layer of loose schor and was flowing along a bed of firmer material. Over a considerable area northwest of the channel the surface layer was wet, so that when walking across it we
Hedin, Tourney in Central Asia. II. 24
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