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.1 |
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| Mutual relations of thresholds and winds. | |
| Formation of a threshold. | |
| Movement of sand upon a dune. |
Citation Information
Fig. 224.
From what has been already said, it will readily be seen that the procedure will be to some extent affected when the depression is filled with water. In that case the western shore remains practically unaltered. We may not assume, that the meeting of the two approaching promontories, under circumstances similar to the bolt() of the Karaunelik-köl, is in any way accelerated by drift-sand being blown from the summit of the dune down into the sound, thus filling it up. If that were indeed the case, the sound would be a good deal shallower than it actually is. Its depth runs to 7.75 m. and 6.13 m., whereas the very deepest sounding we obtained anywhere in this lake was 9.40 m. In other words, the sound is traversed by a deep trough or trench, and this lies immediately underneath the steep leeward wall of the sand-dunes. True drift-sand is not in fact carried to any great distance by the wind, but is brushed up and driven along the face of the dune, over its top, and then falls down on the other side. It is true that, whilst the tempest was careering across the Gölme-käti, we did indeed observe the sand hanging over from the sharp edges of the dunes in the shape of plumes and comets' tails; but they were in each case of brief duration, being speedily broken up by the wind, which
sifted the light dust from the heavy sand, dropping the latter down the leeward face of the dune, but wafting the lighter material away, and
Fig. 225. thus in conformity with the laws of
THE LAKES BESIDE THE LOWER TARIM.
Fig. 223.
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~~~ z //
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