248 THE DESERT OF LOP.
turing power which the wind exhibits in the clay desert is only apparent. I have gone on the supposition, that the wind-eroded gullies and the jardangs are intimately connected with the distribution of vegetation, and that it is the prior presence of trees, bushes, and kamisch which has protected certain parts of the clay desert against the excavating power of the wind, thus leaving it free to concentrate its energy upon the unprotected parts of the surface, or at any rate upon those parts of it in which the roots are more scattered, and consequently possess less binding power. We never found any well-rooted dried up vegetation in these wind-eroded gullies; it was always raised on pedestals, often several meters in height. In the schor desért there exist no traces of vegetation; so that the lake which once existed here must have been as destitute of plant-life as are now the southern parts of the Karakoschun. From the moment when the lake disappeared down to the present day, its bottom has been perfectly bare and homogeneous, and no part of it has offered greater or less resistance to the wind than any other part. If the wind has here gradually planed away the surface layer, as it has done in the clay desert, we possess no direct confirmation of its activity, at least no other means except the form and appearance of the watercourses to which I have recently alluded; they, whilst pointing to the occurrence of the fact, do not tell us the nature of its progress. If now in the northern parts of the Desert of Lop it is the wind-groovings alone that indicate the lines along which the wind has concentrated its energy, while the jardangs with their remains of plant-life alone remain, then, a priori and apart from the varying composition of the ground, the wind's transporting power in those parts of the desert in which vegetation is absent ought to be doubly as powerful. The greatly undercut jardangs are evidence of the intensification of the wind's force when it becomes compressed in the narrow gullies. It formed ages ago the paths in which its great force is concentrated. In the schor desert, on the other hand, its erosive energy is evenly distributed, and it enjoys no opportunity, through working along certain determinate lines only, of leaving distinguishable traces behind it. Were the Kara-koschun to dry up at this moment, and its dry basin, which to the eye would beyond doubt be as perfectly horizontal as the Desert of Lop is, to become exposed to the effects of the wind's erosion, the same result would undoubtedly ensue that we now have in the Desert of Lop — clay desert in the north, schor desert in the south — jardangs in the former, a level expanse in the latter. In consequence of the shape of the lake-basin, the summits of the jardangs would lie at a lower level than the surface of the schor, precisely as we find to be the case in the Desert of Lop. On the other hand, the wind-excavated gullies would be not only less distinct, they would also be less numerous, than in the Lop-nor, for the vegetation in the Kara-koschun is confined to kamisch and sedge; apart from a few bushes, it possesses no arboreal vegetation. On the whole however the result would be like what we see in the Desert of Lop. That is to say, the part of the former lake-basin in which the water was fresh, and organic life, both faunal and floral, was present — the part in which the inflowing river deposited its fine clay-forming mud, would be more accessible to the wing's attacks than the part in which organic life was absent, and its water clear and free from mud, and there accordingly the subsequent dry bed of the lake would be composed of nothing but inorganic matter.
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