STRAT1GRAPH1CAL FFATURES. 63 



overlaid by the Productus shales ; but east of Nilang in Spiti 

 evidences of its erosion in permian times are wanting. There the 

 carboniferous system is very well seen in the fine cliffs near Muth, as 

 shown in the profile pi. 4, which is the view taken from the opposite 

 heights on the right side of the valley. The white quartzite (8) is 

 overlaid in Spiti by flaggy, dark grey, to blue limestone beds, which 

 Limestone above the alternate to some extent with the quartzite 

 quartzite >«. below. These hard splintery limestones 



almost dolomitic in character, have a total thickness of only 50 to 

 70 feet, but yielded abundantly Athyris royssu, Productus sp., etc. 

 Whereas they show by partial interstratification with the white 

 quartzite that they clearly belong to the underlying division (8), they 

 end abruptly above, being overlaid by the dark crumbling shales (9) 

 which ai;e probably of permian age. I have not met these limestones 

 in any other section in the Central Himalayas, but whether I may 

 look upon this division as the last deposits of the carboniferous system 

 or not in the Himalayas is not possible to say, owing to the fact 

 that large tracts of what are now the Central Himalayas have been 

 partially eroded by the early permian seas, and successive strata 

 of the upper carboniferous are overlapped by the permian Productus 

 beds (9). 



There are evidences, both stratigraphical and lithological that 



considerable physical changes had taken place 



close y ofthe h up|tr "car- near the close of the carboniferous period. Not 

 boniferous. on jy j s t h e lithological change from the fine 



grained white quartzite of the upper carboniferous to the crumbling 



black shales of the Productus horizon (9), such as to necessitate the 



supposition that radical changes must have occurred in the outlines 



of the coast, near which the black shales surely must have been 



deposited, but also the latter are found to overlap the several stages of 



the carboniferous in the different sections of the Central Himalayas, 



thus clearly demonstrating the fact that after the deposition of the 



uppermost carboniferous, the distribution of land and water must have 



suffered considerable alterations. At the same time in the Niti area 



( 63 ) 



