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 |
| Southern Tibet : vol.4 | |
| 南チベット : vol.4 |
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引用情報
i6
as in the case of Czaiz -lung yogma, a perpendicularly cut furrow of considerable depth. Since the precipitation during post-glacial, or post-pluvial times has gradually
diminished, the morphological sculpture caused by it has still remained nearly un-
touched, and the erosion terraces are left as they were, sometimes perfectly flat on the top for miles. The fact that the atmospherical destruction has not yet been
able to destroy these terraces, proves that the excavation by the running water has taken place in a comparatively very recent time. The same phenomenon may be studied at the shores of the self-contained salt lakes in Tibet, where the beach-lines are so well conserved since the time when the basins of the lakes were filled to a much higher surface than nowadays. The extraordinary morphology observed from the thresholds of the day's march is, therefore, like a witness or a monument of an activity which has come to an end long ago. But though the amount of water in the watercourses nowadays has diminished in such a high degree, this water, especially during the flood in June and July, is still active in the same direction. It sweeps the bottom of the erosion furrows clean from detritus, sand and gravel, and excavates the valleys, though at a much slower rate than before. Therefore, the weathering gets time to follow the procedure, and the valleys, which in post-pluvial times were cut out in a vertical sense, now assume a more open and trough-shaped form.
Beyond the difficult passage we still march for a while on the top of one of the terraces where the ground is comfortable and even, and the rise, at any rate, not greater than the fall of the brook itself. Sometimes, however, disagreeable places are passed, when the precipice is yawning just at the side of the path, and the brook is hidden in its dark furrow deep below our feet.
From this passage the path goes down to the curious region at the bottom of the main valley which is called Ciuta and where hot springs crop out of the ground. The first one forms a solid pillar in the form of a mushroom, 3 m. high, in the centre of which the water crops out and drops down from its projecting edge, where stalactites are hanging down. Here the water had a temperature of 51° C. About a hundred meters lower down, there is a rather extensive whitish red cake with ten projecting hives or mounds, some of them no more active. From below the edge of this cake a stream of hot water wells out directly into the brook. Here the water is 42° C.; at other places in the immediate vicinity, 43°. At the edge there is another pyramid 4 m. high, consisting of concentric cupola-shaped layers which partly form a vault over a grotto, where there is a water basin in direct connection with the brook. From the direction of the pyramid the water drops down into the basin. The material around the springs is travertine. Some i o m. above the brook, there is another grotto with pouring water also forming a basin, which was cold. At several places on the banks and even in the bottom of the brook itself, water is
THROUGH THE KARA-KORUM VALLEYS.
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