trunks, presenting a remarkable likeness to dry, grey telegraph-poles. As a general rule, the timber of the standing kötäk would seem to be harder and more resistent than that of the kötäk lying on the ground, for the latter is extremely soft, as well as cracked. To judge from its dimensions, the standing kötäk is the younger; the older trees, having the softer timber, and their vitality being more spent, have consequently fallen. When compared with. the living forest which we saw growing beside several of the river-branches of the existing Tarim, the dead forest beside the Kuruk-darja gives the impression of having at no time passed beyond a medium
Fig. 46. PART OF THE DESERT NORTH OF THE KURUK-DARJA.
age. In this respect however it is easy to be deceived; for there can be no doubt, that during the period in which it flowed along the foot of the mountains, the Kuruk-darja, like the existing Tarim, shifted its channel several times. The winding gullies and »corridors» of this dry yellow clay region, in which on several occasions we got entangled, are probably parts of the former course of the river, either arms into which it split or the different beds between which the river flitted to and fro. Under these circumstances the forest did not reach full maturity before it was deserted by the river. But it is much more likely, that this old dried forest has suffered through the effects of the atmospheric forces, and the abrasive and planing action of the wind, in consequence of which the trees are now smaller than they were when alive. It is the upright trees which are especially exposed to the abrasive action of the wind-driven drift-sand, and this is perhaps the sole cause of their being thinner than the trees that lie on the ground. Indeed, it is altogether an astonishing thing, that they are able to maintain their upright position at all. Seeing that they must be at least fifteen hundred years old, one would expect that the countless
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