ACROSS THE DESERT FROM ALTMISCH-BULAK. 229
primeval depression of the surface. In a pit or hollow, some meters deep, near these tamarisks it looked as though the ground-water could soon be reached by digging, and indeed it must have been pretty near the surface, otherwise the tamarisks would not have been able to keep alive. Throughout the day the mollusc shells were very numerous.
Fig. 142. PART OF A JARDANG SURROUNDED BY SAND.
On the 3oth March we were able to travel 20 km. without hindrance towards the S. 16° W. What few jardangs there were were rudimentary, and we were able to avoid them. The sand however became practically continuous, although at intervals fragments of the edges of the jardangs stuck out of it. There are also here bajirs of the same kind as those in the Desert of Tschertschen, although of course in miniature. As a rule they are only 20 to 50 m. long and a dozen meters or so broad, and stretch south-west and south-south-west; this however facilitated our march. The direction in which they lie was unlooked for; for, the prevailing winds blowing from the north-east and east-north-east, the dunes turn their steep faces towards the southwest and west-south-west, so that one would have expected the bajirs to run from the north-west to the south-east or from the north-north-west to the south-south-east. Their position in the Desert of Tschertschen is explicable by the decrease in the quantity of the sand from north to south; but here that explanation no longer holds, for the sand increases towards the south-west and south. This notwithstanding, these small bajirs obey the law of general parallelism, and appear therefore to bear some relation to the wind, or rather to the relief of the clay desert and the wind combined.
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