jardangs, were as hard as asphalt, and though the gullies in between them were full of soft material, it too rested upon hard clay. It is of course inevitable, that those portions of the desert which are accessible to the wind should be swept clean and become hard, as also that the fine drift which drops into the gullies, being relatively sheltered from it, should remain where it falls. In a few places we noticed a thin layer of brown, rather coarse-grained sand, which likewise rested upon the clay. In this direction again kötäk was very plentiful, both standing and lying on the ground. Once there were primitive forests here, of the same kind and appearance as any of the finest forests standing to-day beside the Tarim. In one locality the dead, withered, stumpy tamarisks stood so close together, and were so big, that we had to exercise the utmost caution in threading our way through them ; this had once been an impenetrable tamarisk thicket. A few kilometers east of Camp No. X we perceived a solitary toghrak still retaining a spark of vitality; it was evidently in the same depression as the clump I have spoken of above. But on the whole the desert grew more desolate, and the vegetation nearer the verge of extinction, in proportion as we advanced towards the east.
Fig. 55. VERTICAL SECTION OF THE KURUK-DARJA.
At length we once more reached the Kuruk-darja, striking it at a couple of bends, in which its bed was marked with exceptional distinctness and was unusually well preserved. At the point where we touched it, the river-bed was 94'/2 m. broad, and its containing banks 61/2 m. high. These last were still provided with an abundance of dead forest; on the lower side, next the saj, it kept close to the edge of the terrace. During the rest of the day we followed this same terrace towards the east-north-east, having on our immediate left the flat slope of the detritus scree, backed on the north by a small mountain chain, abundantly grooved, which terminated upwards in a level crest or ridge, with no outstanding summits. And, with a few insignificant exceptions, the slopes of the Kuruk-tagh maintained the same aspect during several successive days to the east. They incline towards the desert, which is perfectly level, at a slow rate and low angle. Owing to the refraction of the atmosphere, the most distant parts appeared to hover a little above the surface of the saj. This is generally narrow, in some places only a few hundred meters broad, and its inclination does not at most exceed a few degrees. Its surface is thinly strewn with fine dark-coloured gravel, principally flint, with soft material underneath it, into which the small stones sank when the camels trod upon them; hence their footprints were distinctly visible, being of a lighter colour. But it apparently needs only a little wind, one day's good blow, or two, for these same stones to become exposed again; of this we had evidence in the footprints of the wild camels. The
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