302 THE LOP-NOR PROBLEM.
historical Lop-nor, one of my most noteworthy proofs, that this could not be the case, was the circumstance that poplar forest is entirely absent on the shores of the former, and alongside the Tarim downwards from Tschigelik-uj. To this observation I never received any satisfactory answer; and, so far as I now remember, the only suggestion offered was that the saliferous character of the ,ground rendered it less adapted for the growth of forests. In Kosloff's pointed reply to me I look equally in vain for any acceptable explanation of the absence of forest. He does, it is true, institute a comparison between the Lop-nor (i. e. Kara-koschun) and barren salt lagoons. As in the case of the latter, the wide-spread tracts of schor round the lake, sometimes as hard as stone, sometimes moist and heavily impregnated with salt, cannot but be destitute of vegetation. »On the immense expanses of schor which cover the greater part of Lop-nor vegetation can only thrive in the parts that are well supplied with fresh water, and even then it consists at first of grass and bushes only.» Then he goes on to say, »Let me once more emphasise the following fact, that formerly the Kontsche-darja abandoned its ancient bed, and now forms between Gerilghan and the Tokum-kul the easternmost arm of the system. At a later period the Kontsche-darja exercised an influence upon the oscillations of the lower Tarim; and every time the masses of water waxed uneasy in their bed there ensued an augmentation of the volume of the western waterway at the expense of the eastern (the Ilek), which was on the point of drying up. In proportion as the water receded step by step, in that same proportion did the vegetable life diminish, and close on the heels of this latter followed the sand-dunes, as they still continue to do, so that as the desert conquered ever wider and wider areas, it strewed its pathway with dead and smothered trees. The highest dunes built themselves up on the border-line between life and death, and it was only that far that the poplar forests and tamarisk bushes died out definitively. In moist places, and these sometimes occupied pretty extensive areas, there appeared here and there salt lagoons and very tiny patches showing traces of kamisch.»
With regard to the first point raised, it will be sufficient to call to mind, that in the whole of the western Kara-koschun, especially along the northern shore, the water is fresh; and that there is nothing in the properties of either soil or water calculated in the slightest degree to prevent the growth of forest is proved by the occurrence of abundant poplar woods in places beside the Tokus-tarim arm all the way from Schirge-tschapghan. No, the real reason is, that the Kara-koschun is so recent a creation that forest, which of course requires time to spread and grow up, has not yet been able to propagate itself into that region. But it will grow up there as time goes on, and in evidence of this I point to the solitary young poplars which have already struck root in a few, but a very few, places. Along several, and sometimes long, stretches of the Tarim, e. g. the Jumalak-darja, we have already noticed the absence of forest, the reason being that the river has changed its bed; and the same thing occurs again beside the great sandy desert below Karaul. Beside the Ettek-tarim and the Ilek, as well as beside the Tokus-tarim, we found, on the other hand, fairly vigorous forest, but then these streams have been stationary for a sufficient length of time.
Beside the lower Tschertschen-darja forest is absent from the point where one may properly speak of a delta, and where the river begins incessantly to change
IIIFカラー高解像度
