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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
JOURNEYS OF BONVALOT, DUTREUIL DE RHINS AND GRENARD.
503
which have been discovered amounts, I am sure, to something like 200. If to these we add the pools and smaller sheets of water, the number will of course easily run up to several thousands.
On the highest parts of the Tibetan plateau the French expedition in 1893 mapped 17 lakes between the Arka-tagh and the Lha-ri Mé-long, all of them of medium dimensions. Nor did they discover any lakes of large size between the sources of the Kerija-darja and the Panggong-ts'o. The largest was the Ma-ouang ts'o, with an area of about 700 sq. km. Grenard estimates the area of Lake Montcalm at less than 600 sq. km. and the A-rou ts'o at less than 500 sq. km. The Lac des Hemiones is computed to have an area of 600 sq. km. Grenard considers it possible that this lake may be made up of two separate basins. The Horpa ts'o covers an area of 300 sq. km. All the rest are each less than 200 sq. km. But large lakes occur south of the range of Mé-long gang-ri. The Tchar-gad ts'o (= Addan-tso) reaches 400 sq. km. The surface of the Gya-ring ts'o (= Sellingtso), which according to Grenard is as long as the Koko-nor, though narrower, he estimates at 1300 sq. km., while the Nam ts'o he computes at 1800 sq. km.
»Les eaux des lacs que nous avons vues sont salées et quelquefois chargées de soufre comme celle de l'Atchyk koul sur le plateau de Gougourtlouk, ou d'ammoniac comme celles du lac sur le bord duquel nous avons campé le i er novembre 1893. Nous n'avons relevé que deux exceptions: le Tchar-gad ts'o et le Nam ts'o dont les eaux sont douces, au moins potables, car nous en avons bu. Nous nous sommes même servi de l'eau du Nam ts'o pendant cinq semaines.»
Grenard states that the expedition was unable to measure the depth of any of the lakes they saw, but he assumes that they are not very deep; and he truly observes: »Le lac Pang kong, dont les eaux ont moins de 45 mètres d'épaisseur ne compte vraisemblablement pas parmi les moins profonds.»
I myself obtained a maximum depth of 48 m. in the Panggong-tso, and this value, which I also sounded in two other lakes, was the greatest I found throughout the whole of Tibet. With regard to depths Grenard distinguishes with perfect correctness between two different groups of lakes. »Les lacs de montagne aux rebords accentués et découpés, tels que le Pang kong, le Ko-né ts'o, le Nam ts'o, le Pam ts'o, le Tchar-gad ts'o, le lac Sinueux, sont plus profonds que les lacs de plaine aux limites indécises, ceints de marécages, comme le Boul-ts'o, le Gya-ring ts'o, le Tag-tsa ts'o, le Soum-dji ts'o. Tandis que le Gya-ring ts'o gèle au commencement de novembre, les eaux du lac voisin, le Tchar-gad, sont libres à la même époque, et celles du Nam-ts'o ne sont prises par les glaces que dans la seconde moitié de décembre.» Otherwise Grenard considers that the greater part of the lakes of Tibet are »mixtes» : 1. e. their shores are partly rocky, partly flat and marshy. Nowhere on the north of the high plateau did they find lakes that were entirely surrounded by mountains. These exist principally in the southern regions, where the surface relief is more accentuated. According to Grenard's observations all these lakes are shrinking in consequence of the heavy evaporation and the small compensation that they receive from clouds and inflowing streams.
»En certains endroits on voit la trace très nette de la baisse des eaux. Ainsi le petit lac Tâchlyk koul, à l'ouest, est ceint de plusieurs gradins superposés,
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