half the distance. Still it is only along the line of traverse I chose that the existence of the depressions makes itself evident; at the point of which I am now speaking there is, on the contrary, nothing to prove that we were within the radius of either the one depression or the other. True, the fact of these sheets of water having direct communication with the Kara-koschun would seem to indicate that we were still within its basin; but the evidence is only apparent, and ceases to carry weight when we call to mind the effects produced by the wind in bringing about changes of level. Whichever lake the belt of vegetation in question may have grown beside, the elevated shore on which it stood would appear not to have borne that character for any very great length of time, for neither the trees nor the bushes had reached a medium age, but were still young when the water deserted them:
Fig. 119.
Then the dead vegetation decreased again; but there was still no living forest, and it was extremely seldom that we saw so much as a shrivelled bush or a prostrate toghrak stem. At one place on this strip of ancient shore we lighted upon fragments of earthenware. Mollusc shells abounded everywhere, in some places in truly enormous quantities. The bedding of the clay in the wind-sculptured jardangs showed that the sedimentary matter had been laid down at different periods. One instance is depicted in the accompanying fig. (119). On the top there is a layer of hard, compact, yellow clay to a thickness of 3 dm.; beneath that a layer of softer darker clay, 8 dm. thick and distinctly folded; and this is underlain by another layer of the hard yellow clay, disposed horizontally. It is clear that in this flat region, over which the Lop-nor has wandered to and fro for so many centuries, there must exist countless instances of changes of this sort. I suppose that the intermediate folded layer corresponds to the ordinary schor formation, i. e. saliferous clay sediment, which dries into »granulated» ridges and folds after the water has flowed away off it. On the other hand the yellow clay with the perfectly horizontal disposition was laid down in fresh-water lakes, and contains a larger percentage of sand, corresponding to the larger percentage of salt in the schor. And the actual distribution of the clay desert and the schor desert around the present Kara-koschun lends support to this supposition: as the schor desert preponderates more and more towards the north-east, so also does the salinity of the water increase in the same direction.
Here too, where we are now pausing, the jardangs are crowned with clumps of kamisch-stubble, and in one place the stubble was so thick and high that in case of need we might very well have used it as grazing for our camels.
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