DETAILED ACCOUNT OF SOME RECENT EXPERIMENTS. 2^ 



The yield of a small artesian reservoir, like that of the Quetta 

 basin, situated in a very dry region, is subject to a certain amount 

 of variation according to differences in the amount of yearly rainfall. 

 The flow from the karez galleries at Quetta is known to be affected 

 to some extent by such variations, and some of them have even 

 been known to stop flowing entirely after prolonged periods of 

 abnormal drought. 



The structure of the recent alluvial deposits in the valley-plain 



Other localities favour- of Q uetta is b y 110 meanS S P eC ' al t0 that ° ne 



ably situated. locality, but is common in a greater or less 



degree to all the talus deposits that fringe the high mountains of 

 Baluchistan and Persia, of that arid table-land known as the 

 plateau of Iran. At many pkces, the water which they contain is 

 tapped by the karez and kanat galleries, and, no doubt, it would 

 be available also by artesian wells. For instance, all along the 

 mountain ranges which form the southern border of the great desert 

 which stretches from Nushki up to the Persian Frontier, these talus 

 deposits frequently assume enormous proportions. At a few locali- 

 ties far distant from one another, karez tunnels have been driven 

 into them, and it would be worth while making an experimental 

 boring at one of the most likely places. 



There is not much that calls for comment in the boring records 

 Boring records of wells of the welIs in Quetta. The deposits are too 

 at Quetta. irregular to allow the identification of strata 



encountered in different wells. In all the borings, the same varieties 

 of sands and clays were met with in alternating layers. The follow- 

 ing records were published by Mr. Oldham in the report already 

 referred to : — 



SECTIONS OF BORE-HOLE3 AT QUETTA AND BOSTAN. 

 I, Well at Railway station— 

 120 feet loess. 



( 2 7 ) 



