CRYSTALLINE SERIES. 



11 



range in the latter district and in Kafiristan, but the geology of these 

 areas is quite unknown. 



Metamorphic and Crystalline Series. 



The Siah Koh was described by Mr. Griesbach (13, 70) as consist- 

 ing of metamorphic rocks — mica and hornblende-schists with crystal- 

 line ruby-bearing limestone — overlain by darker, sometimes compara- 

 tively unaltered, limestone, which he referred to the Carboniferous 

 system. My observations were confined to the western part of the 

 range in the neighbourhood of Jagdallak, but I was able to make an 

 almost complete traverse across it from north to south and, as the strike 

 of the beds is E.-W., I saw a section of the whole series. This corre- 

 sponds well with the section given by Mr. Griesbach, and consists in the 

 main of biotite-gneiss and hornblende-mica-schist overlain by a thick 

 series of crystalline limestone. The whole series is greatly disturbed 

 and the relationship between the schists and the crystalline limestone 

 very obscure. On the south the limestone is in contact with biotite- 

 gneiss — at times biotite-schist — which is pierced by a network of 

 granite veins. The direction and dip of the foliation planes of the 

 gneiss are very irregular and it is difficult to say whether the rock 

 underlies or overlies the limestone. 



On the north side of the Pari dara, the famous defile near 

 Jagdallak, hornblende-schist is found interbedded with the limestone 

 and in the defile itself biotite-gneiss and schists (biotite- and horn- 

 blende-) appear to alternate with the limestone beds. Further to the 

 north-east, however, in the small plain in the Dargai valley, the belt of 

 crystalline limestone is clearly underlain by a series of hornblende- 

 mica-schist and quartz-schist forming an anticline with its crest leaning 

 over to the south. 



At first sight the limestone belt appears to consist of a regular 

 ascending series of almost vertical beds of crystalline limestone with 

 occasional bands of schist interstratified, but a closer examination 



