66 THE KURUK-TAGH AND THE KURUK-DARJA.
and are everywhere pretty much the same relative height above the gullies on each side of them, namely from 2 to 3 meters. To cross a country like this at right angles to the ridges is indeed possible to a man — on foot; but for camels it is both tiring to the animals and trying to the patience of those who travel with them. The only way to advance is to zigzag backwards and forwards through the gaps in the jardangs. After proceeding in this way for some distance, and finding that the character of the country did not alter, and having convinced ourselves that it would be idle to attempt to dig a well, for there was not the smallest sign of a living tamarisk to be seen, we at length turned back towards the north-east. That of course greatly eased our march: we were able to keep to one single gully, and travelled as it were in a passage-way, our view being greatly impeded by the high jardang walls on both sides of us, so that we were obliged to scramble up them time after time to obtain some idea of what the adjacent country was like. Lower down we shall make a more general acquaintance with the Desert of Lop, and I will then compare these jardangs with the other phenomena in the relief of the desert. For the present, I will merely observe, that they are the result of the activity of the prevailing wind. Many instances occur of its having scooped out in the side of a jardang a cup-shaped but elongated hollow, beautifully rounded, forming a sort of grotto with an overhanging cornice. In the end the cornice, which is plainly composed of harder and more compact clay than the material which has been scooped out from underneath it, breaks off, so that it is no uncommon sight to see blocks, lumps, and fragments of hard clay littering the bottom of a gully.
Fig. 6i. VERTICAL SECTION OF JARDANGS.
At the spot where we turned north-east, with the intention of going after all to Altimisch-bulak, there was scarce any kötäk whatever to be seen, except very occasionally a dead tamarisk. Even tamarisk-mounds were very rare, as indeed might be expected in the basin of a former lake. Dunes were: equally absent. We failed to discover even the rudiments of one; although at the same time quite low ribs of sand, or a thin layer of the same, had accumulated in a few places suitably exposed to the wind. But they were too small to be called even rudimentary dunes. The northern part of the Lop-nor is therefore free from sand. In other words, there is no accumulation of drift-sand in the region immediately below the detritus slope of the Kuruk-tagh, the region through which the Kuruk-darja formerly flowed, and in which it formed the lake of Lop-nor. Had the water disappeared from this region at no very distant epoch of time, there would be reason to suppose that it was the water itself, and the rich and abundant vegetation — toghrak forest, tamarisk steppe, and kamisch-fields — which usually accompany the water, that had prevented the sand from forming dunes. But in point of actual fact,
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