62 GRIESBACH : GEOLOGY OF THE CENTRAL HIMALAYAS. 



In the Nilang area and Spiti, the bluish-grey limestones are again 

 more* strongly developed, and the lower division of the carboniferous 

 is consequently of greater thickness there. In all sections, however^ 

 the red Crinoid limestone is present, and lithologically identical 

 throughout ; I think its total thickness anywhere does not exceed 



400 to 600 feet. 



The fossils found in this division are in a very poor state of 



preservation. Casts of Brachiopods^ Orthoceras 

 and Crinoid remains may be said to be the sum 

 total of what has been found in these earthy limestones. 



The red Crinoid limestone is overlaid bv a 



White quartzite (8). . . 



very characteristic horizon, namely, the white 

 quartzite (8). It is generally a fine grained, hard, pure white 

 quartzite, in thick beds ; its uppermost beds are often a fine grit, or 

 quartz sandstone with a few shaly beds dividing it. Near its base 

 I noticed in some sections, though rarely, that beds of red Crinoid 

 limestone are intercalated between the quartzite. I found that the 

 total thickness of this division ranges from 350 feet (in Niti) to 



about 800 in Spiti, where it is particularly well 

 developed. Fossils are scarce in this division of 

 the carboniferous or generally seen only on the weather-worn sur- 

 faces ; they are so closely united with the rock 

 Fossils. .... 



in which they are contained that it is almost 



impossible to extract them. Brachiopods, Orthoceras sp. and Corah 



are seen weathered out on the surface of the rock. 



I found this division of the carboniferous system in the Niti 



sections when I first visited that ground in 1870 : 

 Distribution. .'. & '*' 



it is there partly eroded, and the succeeding 

 Produclus shales (9) rest directly on red Crinoid limestone in several 

 sections. It forms one of the most constant features in almost every 

 one of the sections south-east of Niti as far as the Nepal frontier. 

 Partially eroded the thickness of the white quartzite varies greatly 

 and often suddenly. But nevertheless it is scarcely ever quite absent. 

 North-west of Niti, in the Nilang area it is also present, directly 

 ( 62 ) 



