1873.] BLANFORD — PERSIAN SUPERFICIAL DEPOSITS. 495 



many of the streams become impassable torrents after heavy falls of 

 rain, or when snows are melting rapidly ; but in general they con- 

 tain no water at all, or a very small quantity. In many large 

 valleys there are neither streams nor dry stream-beds. 



These peculiar features of the meteorology and physical geography 

 of the country are mentioned, because without noting them it is 

 difficult to understand some of the problems presented by the super- 

 ficial deposits. As I shall endeavour to show, I believe that the 

 condition of some of these deposits is due to the small rainfall. 



Desert Plains. — The great plains of Persia have been compara- 

 tively but little traversed, all the principal roads passing through 

 the towns and villages on the edges of the deserts. The general 

 surface and character of these plains varies, in all probability, but 

 little throughout. In the smaller plains, and in the larger deserts 

 at a short distance from their margins, the surface usually consists of 

 very fine, pale-coloured, rather sandy earth, which, although barren 

 in general, is fertile wherever irrigation is practised, unless, as is 

 not unfrequently the case, it is strongly impregnated with salts. 

 The actual margins of most plains are stony ; but to these I shall 

 revert presently. The surface is often much covered by blown sand, 

 consisting of small grains of quartz and other minerals, of low spe- 

 cific gravity. These sands are, of course, constantly shifting, and 

 cannot be taken into account, the deposits which form the real sur- 

 face of the country underlying them. 



Salt Swamps and Lakes. — I have already referred to the occur- 

 rence of salt in the desert soil. Most of the few streams which 

 exist terminate either in salt marshes or salt lakes. Thus the Jaji 

 End* and Kirij, running from the Elburz, one on each side of 

 Tehran, and other streams coming from the neighbourhood of 

 Kasvin and Hamadan, all terminate in broad tracts of salt swamp 

 on the margin of the great salt desert which separates north-western 

 Persia, or Irak, from north-eastern Persia, or Khorassan. Further 

 south the Zenderud, which runs through Isfahan, loses itself in a 

 similar swamp between that city and Yezd ; and on the road from 

 Karman to Shiraz, Major St. John and I crossed a salt marsh formed 

 at the termination of a stream draining the south-eastern continua- 

 tion of the plain in which the Zenderud runs. The so-called Ban- 

 damir of the maps runs into the salt lake of Niriz, and the Shiraz 

 salt lake receives the drainage of the Shiraz plain, the existence of 

 a lake in these localities, instead of a marsh alone, being probably 

 due to the greater rainfall. In dry years these lakes, which are 

 very shallow, nearly disappear, and the greater portion of them be- 

 come swamps, covered with a thick incrustation of salt. The salt 

 lakes of Van and TJrumiah probably resemble those of Niriz and 

 Shiraz. To this apparently general rule amongst rivers entering the 

 Central-Persian plateau, of terminating in a salt swamp or lake, the 

 Helmund river offers a remarkable exception, since the shallow lake 

 or marsh of Sistan, into which it runs, is said to be quite fresh. 

 This lake, like some of the others, dries up to a great extent after 

 * "Rud," Persian for a river. 



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