it had, it would have followed the shore-line, which, as a consequence of the uninterrupted shrinkage of the lake-basin, has steadily advanced southwards. The information which the Lopliks have to give agrees in an unambiguous way with the actual circumstances. The Lopliks say, that this long strip of dead poplars, often broken and irregular though it is, stood formerly on the banks of the Schirge-tschapghan arm, through which the Tarim at one time poured its entire flood, and beside the Lake of Utschu-köl, of the existence of which Pjevtsoff also learned something. In his book already quoted he says (p. 307), »In the far distant past, when the Jarkentdarja (Tarim) emptied itself into the lake of Utschu-köl, 7 versts north of its present mouth, there was no connection of any kind between the lakes of Kara-buran and Lop-nor (i. e. Kara-koschun). They were separated by a belt of dry ground at least 4o versts in breadth, and each lake was fed by a different river, the Lop-nor by the Jarkent-darja and the Kara-buran by the Tschertschen-darja. According to tradition, the Jarkent-darja in the space of four years carved a path for itself southwards to the Kara-buran, and from this lake there issued soon afterwards an arm which joined the adjacent lakes, whereupon the Utschu-köl, began to dwindle, until finally it dried up altogether. Traces of its basin still remain.»
It was therefore through the existing Tokus-tarim that the Tarim formerly emptied its water into the Utschu-köl. The actual position of this lake is however somewhat doubtful, though it is probable that it, or a part of it, was situated where Pjevtsoff supposes it to have been. The poplar forest we are discussing grew on its southern shore, and it is very likely that the lakes which were formed to the north of the Kara-koschun in 1900 and 1901 coincide with the basin formerly occupied by the Utschu-köl. However that may be, it is certain that these old poplars were associated with a former lake which has now disappeared, and not with the existing Kara-koschun. If this latter were the case, we should be able to find at least one small poplar on its present shores, but for such we look in vain. The specimens, Io and 15 years old, which are found near the lake farther west, came with the water from above. But on the land journeys that I made in the neighbourhood of the lake I never saw the slightest indication of a young toghrak. The strip of toghrak in question is exceedingly sharply defined and narrow. The fact of our not finding here any old river-bed to cross suggests that we were in the basin of the old lake. On the other hand, jardangs of the kind we are familiar with were common everywhere, and had evidently been scooped out by the wind since the Utschu-köl disappeared, so that its disappearance must date a good long time back. The kamisch-stubble was now more abundant; but whether it belonged to the Utschu-köl or to an expansion of the Kara-koschun it would be difficult to say. Here too it stands upon clay terraces seldom more than one meter high; this points to the kamisch being old, so that it can hardly have anything to do with the last-mentioned lake.
The dunes grew lower and lower, and were scattered, with their horns pointing towards the south-west. This sudden decrease in the amount of the sand in the vicinity of the belt of forest is not due to chance, but is a direct consequence of the hindrance placed in the way of the moving sand by the waterways that formerly existed here. During the interval that has elapsed since this region was laid dry,
Hedin, ,journey in Central Asia. II. . 22
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