DESCRIPTION OF SECTIONS. 2$$ 



volcanic breccia, similar in nature to those of Saindak and Sia"h Koh 

 (see pages 79, 80). 



At the point (e) and beyond it, the cleavage is much less marked 

 than in the more south-western portion of the section. At (/) there 

 are some contortions, and at (g) there is again a very tall range 

 formed of the same columnar igneous rock as at (d). Its enormous 

 thickness quite dispels any doubt as to the possibility of its being a 

 lava-flow. It is clearly an intrusion and from this it appears very 

 probable that the other columnar rocks of similar appearance are all 

 intrusive. In the present instance the rock is remarkable for the 

 large amount of micropegmatite which it contains, but it is more 

 basic than the granophyres of the Afghan boundary mentioned above 

 (page 66). 



Beyond the range (g) is a plain entirely covered with " dasht", 

 with the exception of some very small ranges only the crests of 

 which show above the superficial formation ; they are perhaps the 

 continuation of some of the tertiary ranges of Saindak. Beyond 

 them rises the Amalaf range which is the continuation of the north- 

 eastern range of Saindak. 



Mir jaw a. 

 South-west of the ranges just described there is a great plain 

 covered with recent deposits called the " Dasht-i-Tahlab ", It sepa- 

 rates the ranges hitherto described from other ridges running with 

 a parallel strike and bearing successively from south-east to north- 

 west the names of K6h-i-Tahlab and K6h-i-Rihi. Another longitudi- 

 nal plain occupied by a somewhat important river which bears the 

 name of Tahlab river in its lower course and Mirjawa river in its 

 upper portion further separates the K6h-i-Rihi and K6h-i-Tahlab from 

 other ranges to the south-west. The width of the Dasht-i-Tahlab 

 gradually decreases in a north-western direction, so that the 

 ranges that border it coalesce into a belt of parallel ridges which 

 occupy a tract as much as twenty miles wide between Mirjawa and 

 Amalaf. The alluvial plain of the Tahlab or Mirjawa river still 

 continues in a north-west direction up to a certain distance 



( 77 ) 



