PHYSICAL FEATURES. I9I 



of these important depressions are by no means coterminous, but 

 are separated by a number of minor independent depressions. 

 Occasionally one of these may be unusually deep, and owing to some 

 exceptionally favourable water-supply may allow the formation of a 

 Perennial " pools or perennial sheet of water. These small ponds are 

 called " nawar." They usually are surrounded 

 by a cultivated oasis and supply water to the nomads and their 

 flocks often to great distances. Shady tamarisks, many centuries 

 old, grow by their banks, and the women who come to fill their 

 "mashks" with water, the sheep, cattle, and camels which in count- 

 less flocks come to quench their thirst, form a busy scene which 

 affords a strange contrast to the awful silence and desolation of the 

 surrounding desert. 



Everywhere the topography shows that rudimentary and un- 

 finished sculpturing of the earth's surface, characteristic of regions of 

 extreme dryness. As already mentioned, the rivers pass almost 

 without transition from the condition of a mountain torrent to that 

 of a delta. Even where in a somewhat more favoured mountainous 

 district a number of valleys unite to form a channel of some import- 

 ance, the same particularities are observed on a smaller scale. 

 Just as the larger channel ends abruptly where it leaves the mount- 

 ain district to break up in a wide fan at the edge of the desert 

 plain, so do the tributaries of that channel end abruptly when they 

 join its course. Usually there is a small fan talus at the termination 

 of each of the secondary ravines. The section of the main valley is 



distinct from that of the Helmand, and it receives a scanty supply of water from the streams 

 that flow from the northern and north-eastern slopes of the hills about Amir-Chah, Saindak, 

 Malik-i-Siah-K6h, etc., many of these stream-beds being more or less choked by blown sand. 

 But when the flood of the Helmand is exceptionally abundant, the water of the combined 

 lakes of Seistan rises to the level of the low watershed and flows through the channel of the 

 Shelag river into the Gaud-i-Zirreh. Thus the entire basin of the Helmand becomes 

 tributary to that of the Zirreh lake. 



It is only lately that our geographical knowledge of this region has been completed. 

 The true nature of the Shelag river, and the fact that the Gaud-i-Zirreh is a salt-water lake, 

 do not seem to have been fully realized' at the time when Mr. Blanford wrote his works upon 

 Persia. The existence of an outlet to the Seistan lakes removes the apparent anomaly 

 mentioned by him, of the Helmand terminating in a fresh-water lake (Quart. Journ. Geol. 

 Soc, Vol. XXIX, p. 495), for the Zirreh lake contains nothing but brine. 



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