GHORBAND. 



47 



various colours, including white, grey and red. With it are associated 

 quartzite and some slightly schistose slate. These rocks form the high 

 hill — Takht-i-Marwan — behind Jabl-us-Siraj ; on the top of this hill 

 and on its northern and western flanks, the sedimentary beds are pene- 

 trated by bands of schorl- granite, which is no doubt accountable for 

 the local metamorphism. 



The mutual relationships of the hematite and limestone are here 

 Ashawa and vev J 00scure J the one sometimes replacing the other 

 Kaoshan. quite unexpectedly. This might perhaps be attri- 



buted to chemical replacement of the limestone by hematite, but I am 

 more disposed to assign it to irregularity of outcrop consequent on the 

 extraordinary contortion, probably combined with overthrusting, that 

 the beds have undergone all through this part of the Hindu Kush. A 

 good example of the prevalent type of folding is seen on a spur run- 



Fig. 5. 



Folds in the Kalu. series near Jabl-us-Siraj. 

 ning down towards the plain between the Salang and Ghorband rivers 

 (see fig. 5). At Matak, at the mouth of the Ghorband valley, the 

 rocks on either side of the gorge are at first dark grey gneiss with 

 porphyritic felspar. The rock often has a curiously conglomeratic 

 aspect, which may perhaps be due to the effects of pressure tending 

 to produce an autoclastic conglomerate. Immediately above the gorge 

 the gneiss is replaced by graphitic slate, thin-bedded limestone and 

 quartzite. A little further back in the hills the hematite bed runs 

 across from Ashawa to Parwan. The horizon is a most useful one, and 

 can be traced up the left side of the (ihorband valley almost all the way 

 to Siah-gird. Throughout this part of the valley the lower slopes of the 

 Hindu Kush are formed of the Hajigak series —as represented by the 



