Notes on Geology and Mineralogy of Affghanistan. 605 



ranges are interposed ill cultivated stony plains, varying in 

 breadth, and shelving down from the hills on either side 

 towards the centre, the surface being for the most part 

 thickly strewed over with loose rounded stones. The direc- 

 tion of all these valleys is of course that of the ranges by 

 which they are bounded on either side, and these, running 

 from N. E. to S. W., cause likewise the rivers, which flow 

 between them, to pursue a course nearly parallel to the bar- 

 riers which wall them in on either bank. Many of these 

 rivers are lost in the sands, without effecting a junction with 

 each other, such as the Lora from Shawl, the Doree, and 

 the Turnuk, but others rising in the lofty mountains to the 

 northward, afford a plentiful supply of water all the year, 

 and eventually discharge themselves into the great Lake of 

 Seistan. 



The direction of all the rivers is at first direct for the 

 sandy desert, which stretches across the southern end of 

 the valleys from the district of Shorawuk, through Gurm- 

 sael, Seistan, and across the frontier, until it becomes ap- 

 parently incorporated with the desert of Kirman, and the 

 great salt desert of Khorassan. 



On reaching the desert however, instead of continuing on 

 their course, and diffusing yegetation in their progress, the 

 direction of all is suddenly changed from S. W. to about 

 West, by which means the desert is merely skirted by them, 

 and its sands being deprived of the fertilizing effects of 

 their waters, are left to drift before the wind in endless 

 barrenness. 



This sudden change in their course which is common 

 to all the rivers, namely the Lora, Doree, Argandab, and 

 Helmund, evidently betokens a fall in the level of the coun- 

 try, which causes the streams as soon as they have freed 

 themselves from the restraint of the mountain ranges, to obey 

 the laws of nature, and turn westward down the slope, until 

 such as are not previously lost in the sands, either effect a 



