214 GRIESBACH : GEOLOGY OF THE CENTRAL HIMALAYAS. 



Descending the valley, he came up with the white quartzites near 

 the village of Muth, which are further on overlaid by black "Ruling" 

 shales ; and I think he must have believed that it and the silurian 

 quartzite belonged to one formation. But there is no silurian rock 

 near Muth itself; and the white quartzite near that village is upper 

 carboniferous, as will be seen further on. 



The upper silurian (5) is conformably overlaid by a thickness of 



from 700 to 800 feet of a very dark, hard lime- 

 Devonian limestone (6). 



stone (6), concretionary in parts, alternating 



with dark, splintery shales. This series also has a wide geographical 

 distribution, from the Nepali frontier in Byans, where it attains much 

 greater thickness, to Spiti, little if at all varying in lithological char- 

 acter and containing few fossils. I found none in Spiti, and those 

 met with in the eastern section might either be lowest carboniferous 

 or devonian. Studying it connectedly with the adjoining horizons, its 

 geological position at the base of the carboniferous is apparent; and 

 then the uniform lithological character of the horizon over an exten- 

 sive area is striking, but little could be gained by simple lithological 

 identification in the field unaided by a clear view of its geotectonic 

 conditions. Almost identically the same rock may be met with in 

 higher horizons. 



I think it is very probable that this same series extends far into 

 Kashmir, as shown by Lydekker, 1 who places it into the carboniferous 

 system. Lithologically similar rock occupies a carboniferous horizon 

 in the Hindu Kush sections and in the prolongation of this mountain 

 chain through north-western Afghanistan and north-eastern Persia 

 where it probably thickens out and runs into upper carboniferous. I 

 am induced to correlate it with devonian rather than carboniferous; 

 the fossils found in it in the Central Himalayan sections, as far as I 

 have been able to examine them up to this, might be characteristic of 

 either devonian or lower carboniferous, but its evident connection 

 through passage-beds and alternations of strata with the underlying 

 upper silurians indicate that at all events between the upper portion 



1 Mem. Geol. Surv. Ind., Vol. XXII, 1883. 

 ( 214 ) 



