66 



IIAYDEN : GEOLOGY OF NORTHERN AFGHANISTAN. 



beds of Cretaceous limestone. Above tbe gorge, the valley on either 

 side of Dasht-i-Safed is filled with Tertiary beds which overlie the 

 Cretaceous limestone conformably on the south, but on the north have 

 been over-ridden by older beds along a thrust-plane which runs across 

 the vallev and through the Dasht-i-Gazak into Begal in Upper Saighan. 

 Above Dasht-i-Safed the rocks met with belong at first to the Red 

 Grit series, but at a short distance above Andao, there is another 

 deep gorge through the Cretaceous limestone. Here the Kahmard 

 river turns at right angles to its former course, and after running 

 from Saripul to Bajgah along a synclinal trough in the Cretaceous 

 limestone, suddenly swings round and cuts its way out across the 

 southern limb of the fold. At the lower end of the gorge, the lime- 

 stone is full of fossils ; a red arenaceous bed is particularly prolific and 

 contains Hippurites, Gryphaa, Exoggra, Pecten, Neithea, Turritella 

 and many other lamellibranchs and gastropods. Cyclolites sp. also 

 occurs. No doubt this is Mr. Griesbach's ' Exogyra limestone/ Just 

 above the gorge the prolongation of the Kahmard trough contains an 

 assemblage of beds similar to those above the Cretaceous limestone 

 near Dasht-i-Safed. The flaggy calcareous shales are the same and 

 here also are associated with gypsum aud sulphur, but the latter occur 

 in very much smaller quantities. 



Kahmard proper is a long narrow valley lying along a fold in the 



,, , . Cretaceous limestone : the northern side of the 



Kahmard. 



valley is formed by a recumbent anticlinal arch 

 from the crest of which the younger beds have been removed, allowing 

 the underlying Red Grit series to crop out here and there. The south- 

 ern side is a great bare wall of rock many hundreds of feet high and 

 sloping at an angle of about 40° from the edge of the Dasht-i-Gazak 

 down to the river-bank ; so closely does the valley follow the axis of the 

 fold that for long distances the surface of this wall is a single bed of the 

 Cretaceous limestone. Plate 17 is a photograph of Bajgah gorge (Tangi 

 Bajgah) from the north. Through the gorge is seen the sloping 

 surface of the Cretaceous limestone which forms the southern wall 



