26 



HAYDEN : GEOLOGY OF NORTHERN AFGHANISTAN. 



to the south of Siah-gird, the beds dip at high angles to the north- 

 west and thus appear to underlie the crinoid limestone of Waghzar 

 which I regard as the continuation of the Devonian beds of the Kotal-i- 

 Hajigak. 



In the Parsa valley, on the other hand, the same rocks continue with 

 a steady south-easterly dip right up to the granite which forms here the 

 crest of the Paghman range. 



On the opposite side of the Ghorband valley, the crest and south- 

 eastern slopes of the Hindu Kush consist largely of slate, schist and 

 quartzite. Good sections of these are seen on the way up to the 

 Cbahardar pass and on the heights at the head of the J u-i-dukhtar. 1 

 Metamorphism by the granite is very general here, and correlation can 

 be only tentative, but I am disposed to regard these rocks as a meta- 

 morphic facies of the Helmand series. 



In the hills between Bamian and Saighan, there is a similar series of 

 slate, schist, graphitic schist and quartzite, which may represent the 

 Helmand series with perhaps some of the underlying horizons. Like 

 the sections in Ghorband those in Saighan are obscured by intrusive 

 granite, and one cannot refer these beds confidently to the Helmand 

 series. The graphitic schist rather suggests the Kalu series, but I have 

 not observed any representative of the hematite bed. 



In the neighbourhood of Ak Robat, the rocks which I have referred 

 to the Helmand series are overlain by crinoid limestone which contains 

 Fusulina, and is probably of Upper Carboniferous age. The Helmand 

 series is therefore presumably Lower and Middle Carboniferous, and 

 fills the gap between the Hajigak and Pusulina limestones. 



Fusulina Limestone Series. 



Prom the middle of the Ghorband valley above Siah-gird to 

 Ak Robat in Bamian, there is a continuous belt of limestone and slate 

 Por the most part the limestone is a dark grey, more or less crystalline 

 rock with numerous veinlets of calcite. No fossils have been found in 

 it in Ghorband, and I consequently refer to it in that valley as the 

 1 Ju or Juy = a stream {Pers.) 



