62 



HATDEX : GEOLOGY OF NORTHERN AFGHANISTAN. 



north-eastwards under the Kotal-i-Kalich and on towards Barfak, Tala 

 and the valley of the Andarab. The chief difference between the 

 stratigraphical sequence in Saighan and that found in the more easterly 

 area is the thinning out and disappearance of the Red Grit series in 

 Saighan. In the valley of the Kahmard river, between Dasht-i-Safed 

 and Doab, and eastwards as far as Tala, this series is between one and 

 two thousand feet thick. To the west of the Kotal-i-Kalich, however, it 

 gradually begins to thin out, and on the hillsides above Khwajaganj, 

 it disappears altogether, the Cretaceous limestone overlapping on to the 

 Saighan series. 



Throughout lower Saighan the junction of the Doab and Saighan 



series is obscured by horizontal deposits of Upper Tertiary age. On 



the right side of the valley of the Kahmard river, however, just 



opposite the village of Doab-i-Mekkzann, dark sandstones and 



shales of the Doab series are found dinning to 

 Doab=i-Mekhzarin. rr ° 



the south and forming a low arch on the left 



bank of the Saighan river (Ab-i-Saighan) ; on the north they are over- 

 lain by the Saighan series ; the nature of the junction was not clear, 

 and it may have been a faulted rather than an unconformable one. On 

 the opposite side of the river, at Doab village, the dark sandstones and 

 shales dip to the north, and are overlain by trap, dykes of which cut 

 across the sedimentary beds. Here the junction with the overlying 

 Saighan series appears to be a conformable one ; this appearance, how- 

 ever, seems to be due merely to approximate identity of dip in the two 

 series, and evidence gathered further eastwards between Doab and 

 Ishpushta points to the presence of an unconformity, although the 

 Khargin section already described {supra, p. 60) indicates that this 

 is not of great importance 



On the right bank of the Saighan river, a short distance above its 

 junction with the Kahmard stream, the Doab series appears to lie 

 unconformably on massive limestone which occurs in considerable thick- 

 ness along the southern side of the river. Unfortunately, the bridge 

 over the Surkhab had been swept away and the river was impassable. 



