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
DESCENDING FROM THE HIGH PLATEAU.
251
.1
and then trickles slowly westwards towards the big basin, which no doubt possesses an underground emissary. Thus the water is renewed with extreme slowness, though still fast enough not to acquire even so much as the slightest flavour of salt.
After that we left all the gypsum expanse to the south, travelling across hard gravelly saj, which slopes down gradually from the foot of the moderately high, rocky range, that ran quite close to us on the north. The opposite range on the south is bigger, and was then streaked with snow. The lake was once narrow, of the same type as the Luma-ring-tso. On its northern side it has only a single strand-terrace, two or three meters above the lowest part of the depression, distinctly though not sharply outlined, and with a gentle fall. It looks as if it were so long since the lake dried up that all its older, higher strand-terraces have been planed away. But that is so in appearance only; as we shall soon see, there exists another explanation of the absence of strand-terraces here. Although this lake may be said to be akin to the Luma-ring-tso and the Tsolla-ring-tso, it has reached a more advanced stage of desiccation than they have. In their case portions of the former
Fig. I47. GYPSUM ELEVATIONS.
,.,
lake still survive, their area varying according to the season; but in this new depression there is no part of the old lake left, for the pools which we observed are fed continuously by springs. In order to understand why no strand-terraces have been able to form around this old lake above a certain height, we have only to call to mind two or three hypsometrical data, which, although not per se absolutely trustworthy, are nevertheless in agreement with the conclusions suggested by a study of the conformation of the ground, that is to say of the eroded watercourses. We found that the old lake depression lies at an altitude of 4,573 m.; Camp CXXXIII, farther on in the same latitudinal valley, had an altitude of 4,597 m.; and a spot quite close to Camp CXXXIV an altitude of 4,549 m., though after that the surface slopes steadily down to the Tso-ngombo. Thus Camp CXXXIII will have stood very nearly on a swelling that serves as a water-divide in the latitudinal valley, but the divide rises so little above the existing level of the lake that any idea of the existence of old strand-terraces is absolutely precluded. In other words the depression belongs now to quite a different category of lake depression from, say, the Lakor-tso. That is to say it cannot have been deep; it was a lake
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