I noticed all over Persia, and in Beluchistan as well as here, that these sand barchans, or barchanes, will only form on level ground—generally on extensive plains. All single sand hills, however, whether barchans, conical, semi-spherical, or of more irregular shapes, are invariably caused by a primary obstacle, however small, arresting the sand. Various are the theories with regard to the formation of these barchans, and especially with regard to the formation of the hollow on the lee side.
The explanation from my own observation has—if no other—at least the merit of simplicity. The wind, on meeting the semi-circular back of the barchan, is diverted on the two sides of it; these two currents come into violent collision again on the lee-side, where, the air being more or less still, a considerable portion of the wind is forcibly driven back towards the barchan, corroding its side in a double rotatory way, each such circle having for a diameter the radius of the barchan crescent containing them. In fact in many barchans the sand ripples on the windward slopes cross the direction of the wind at right angles. A line of sand formed in the centre of the barchan crescent in the opposite direction to the wind is often to be seen during wind storms or soon after. I have also seen barchans, the inner crescent of which showed beyond doubt that when there is a prevalent wind from one side only, the above explanation, although less scientifically obscure and elaborate than most, applies, and, I think, it may eventually be found quite the most probable.
The diagram here given will illustrate and, I hope, make quite clear the meaning of my words. In the centre of the crescent can be noticed the action of the parting wind currents.
A Caravan of Donkeys in Afghanistan.
North of Kirtaka was a very pointed high conical hill, and not far from it a small replica of Fujisan in Japan, so much were the lines like those of the Japanese mountain. A great many of the drain channels from the mountains to the south extended very far into the desert and some as far as the God-i-Zirreh.
It is also very probable that in the days when Sistan was a most populous region, with uninterrupted towns and villages along and near the Halmund, numerous canals may have intersected the Zirreh region and rendered it a very fertile plain. History would indeed point forcibly towards such a hypothesis. Ample proof that the plain was inhabited still remains in the ruins of Godar-i-Chah, situated at the western limit of the Zirreh salt deposits, Chah-i-Mardan, where a ruined fort and a Ziarat are said to exist, Gumbaz-i-Chah, and others. All these places are now deserted and are being fast buried by the sand. They are mostly along the Shela (river) banks, and the natives of Sistan say that they have heard from their ancestors that when the Shela did flow freely its water was quite drinkable.
There was a well at Godar-i-Chah—hence its name, "the well of Godar"—almost entirely dried up and of water so foul that it was not possible to drink it, and another just as bad was said to exist at Gumbaz.
It would be most interesting if one could get at the actual history of this part of the world and gain an insight into its former prosperity and civilisation. It is quite probable that Alexander, in his progress through Beluchistan and Sistan, must have come through this country. No army—not even with a new Craterus at its head—could, of course, march elephants, camels and horses through that country to-day, and this has led some critics to doubt that Alexander could have done so, or to believe that, if he did so, he must have been deceived by his guides who tried to bring him as far as possible from water. But those critics forget that in Alexander's days this portion of country was extremely civilised, fertile, and supplied with plenty of water—or else how can we account for the innumerable ruins we find there, and for the many canals for irrigation?