| | | 200 WESTWARDS TO LADAK. race only, which however was very conspicuous in the flat country, for it is 4 to 5 m. high and slopes down steeply towards the depression. Here was a little rivulet issuing from a spring and still flowing, which had carved out for itself a deep and sheltered bed. Next we passed a projecting elbow of the terrace and then crossed over a dry watercourse. After that we came out upon the open country southwest of the lake. Here, upon looking around us, we perceived three terraces, all very distinct, though the highest was not, I suppose, more than 20 to 30 m. above the level of the lake. The lowest, which we followed, sometimes close at hand and sometimes at a greater distance, defines a former beach-line of the Perutse-tso, and it is not so very long since it was abandoned, as is abundantly proved by the properties of the ground. Where dry, this was rough, lumpy, and cracked, of the sanie type as the similar dry expanses that occur, for example, west of Temirlik, or in the vast region of Tsajdam or around the Kara-koschun. It is in fact typical schor, the bottom of a salt lake recently laid bare. Such surfaces are however relatively rare below the lowest of the terraces which I have mentioned, for the greater part cf the country there is occupied with extensive marshes, with grass growing amongst them, and several open pools, all at that time frozen over. In numerous places there were also springs ; and the water in the locality was generally fresh. It would require but a slight rise in the level of the lake to put this marsh under water, and possibly this does sometimes happen. Except the relatively low terraces which I have mentioned, we saw no others in the region round this lake. However, they are sufficient to justify us in subsuming the Perutse-tso under the general rule, that all the salt lakes in central and western Tibet, indeed we may safely say all the salt lakes throughout the Tibetan highlands, are undergoing a process of desiccation. On the northern and north-western shore of the lake rise three mountain bluffs, though at the great distance at which we were from them it was impossible to determine whether they stood close to the lake or were separated from it by a broader stretch of flat, level ground. These mountains, which are practically isolated, are of insignificant size. To the west we perceived several ranges of higher mountains, though to the north-west the country was open right away to a very far-off range. This was the latitudinal valley in which we were to march during the next few clays, and of which the Perutse-tso forms a special part. Our Camp CXVII, beside the Perutse-tso, stood at an elevation of 4497 m., only a couple of meters above the lake. Here the grass was thick and soft, although withered; for that part of Tibet it might however be pronounced excellent. West of our camp was a long belt of balghun bushes, which not very long ago stood on the actual lake-shore. These furnished us with a plentiful fuel. As there was likewise an abundance of spring-water, this locality may with reason be pronounced one of the very best that we had seen since we left "hscharklik. There were marshes also to the south-west of the camp. On our arrival we found 25 Tibetan horsemen, with some forty yaks, waiting to escort us on our way. It was from them that we learned the true name of the lake, Perutse-tso; for our old escort had called it Jim-tso. From this place the distance to Tok-dschalung, to which there was said to be a road farther south, was approximately the same as to the lake of Tschag-tsaga, or about six days' march. |
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