SURVEYING THE DESERT. 245
too the ground is seamed with dark gaping cracks and holes, or the schor laminœ are piled up in heaps, leaning one against another like drift-ice on a river. These irregularities of surface must therefore be due to other causes than those from which the jardangs have originated. The wind cannot have had anything to do with them; on the contrary, it appears to be powerless to produce any effect upon this hard surface, an almost stone-like cement of sand, dust, lime, and salt, with additional patches of salt embedded in it at intervals. It is of course possible to suppose that this region has been dried up too recently for wind-grooves to have had time to form. But the more likely explanation would appear to be the great resisting power of the schor material. In the clay desert farther north the conditions are not thé same. The drift-sand which the wind blows before it acts as an abrasive, without the aid of which the wind would never have excavated such deep gullies as now exist between the jardangs. The relatively soft clay soon yields to the incessant filing. But the schor is incomparably harder than the clay just alluded to, so that the drift-sand is unable to make any perceptible impression upon it.
Fig. 152. SURFACE OF THE SCHOR DESERT.
This part of the Desert of Lop resembles, down to the minutest details, the belt of schor which stretches along the southern shore of the Kara-koschun; the only visible difference is, that the swellings and ridges of the Desert of Lop are a little the higher, while in shape and appearance they are exactly like those to the south of the Kara-koschun. In this respect therefore there is still a striking resemblance between the northern and the southern depression of the desert. The northern basin is shallowest towards its southern side; the water there would appear to have been saltish, just as that of the Kara-koschun is now in a similar part of its basin, and in the same direction too the former would appear to have been devoid of vegetation. In both basins alike, as a natural consequence of the bathymetrical relations, the water has disappeared from the south to the north. When I visited the southern side of the Kara-koschun it was characterized by an absence of faunal life; along the stretch of desert which we covered on i 4th March we did not see a single fragment of a Limnæa shell. It is impossible to say how far the periphery of the former lake of Lop-nor was of the same shape as that of the existing lake of Kara-koschun, because all that I have to depend upon is a single surveyed line. But I believe that in this respect the one was like the other, that is the long axis of each extended from southwest to north-east, or from west-south-west to east-north-east. This agrees with the predominant relief of the desert formations, as we have seen, at any rate, in the arrangement of the wind-excavated gullies, the jardangs, the dunes, and the watercourses, and especially in the recently formed desert lakes. But this same parallelism does not exist on the southern shore of the Kara-koschun; its shore runs in a straight line. The circumstances seem to point to the general law, that where the shore
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