STRATIGRAPHICAL FEATURES. 57 



Upper Silurian (5). 



The dark Coral limestone beds and shales of the lower silurians 

 are conformably overlaid in the Central Himalayas, by a series of 

 strata eminently characteristic for the silurians in this area. Near 

 the contact of the two divisions, the strata forming the latter alter- 

 nate, so that one may say that the lower silurians, although chiefly 

 calcareous, pass gradually into the upper division, which is almost 

 entirely quartzitic ; in the uppermost part of the lower silurians some 

 of the limestone beds are replaced by quartzitic strata, which gra- 

 dually increase in frequency, till in the lowest portion of the upper 

 division of the silurians, the limestone beds, disappear almost entirely, 

 and the prevailing type of bed is that of a quartzite. The general 

 character of the division may be said to be an alternation of evenly 

 bedded dirty pink to flesh-coloured quartzites, with greyish green 

 friable shales dividing them. 



I found the thickness of this division to be from 1,000 to 1,200 



feet in the Niti sections, but it attains a much 



Thickness. 



larger development in the sections north-west 



of the Mdna heights and in Spiti. 



Traces of organic remains abound in all the beds composing the 



upper silurians, but they also await determination 

 Fossils. 



in common with the remainder of the Himalayan 



collections. 



Stoliczka's work in Spiti constitutes so to speak the first critical 



examination of the various geological forma- 

 Spiti. m . 



tions of the Central Himalayas. Strachey's 



researches have reached the scientific world in the form of a short 



paper only, in which all details had been avoided. It therefore 



happened that the Spiti sections, as far as known, became type 



sections, and the stratigraphical nomenclature adopted by Stoliczka 



was afterwards introduced into later writings on Himalayan geology, 



as for instance Lydekker's " Cashmir." This is to be regretted 



for Stoliczka's work of one season was naturally fragmentary, 



and his classification of formations partly based on wrong data. 



( 57 ) 



