STRATIGRAPHICAL ELEMENTS : CRYSTALLINES, ETC, 53 



eyes of quartz. Under crossed nicols the slice shews plain evidence 

 of crushing and the formation of mylonitic structure. This specimen 

 was taken close to a band of gneissose-granite. 



Other arenaceous rocks belonging to this category are more of 

 the nature of glassy quartzites, 



In contrast to the more arenaceous type of schistose rock just 



described come the silky- surfaced argillaceous 

 Phylhtes. J *> 



schists or phylhtes. In the neighbourhood of 



Mansehruh they are not prominently noticeable, but in the Gundgurh 

 range they are a marked feature. The northern part of that range, 

 stretching from near Turbela to the south-west confines of Hazara, is 

 composed of a great expanse of rocks, which are transitional between 

 the normal slates of the Slate zone and the more perfect crystalline 

 schists to be afterwards described. One of the first features indi- 

 cating the beginning of a metamorphic condition is the presence of 

 vein-quartz ramifying through the rocks. A noticeable instance of 

 this occurs near Sobruh Gulee, where the very slight alteration that the 

 slates have undergone would be scarcely appreciated were not the 

 attention drawn to it by the numerous veins of quartz. 



The arenaceous type and the argillaceous type of faintly schistose 



rocks are often observed interbedded together. 

 Interbedding of the 

 arenaceous and argilla- In the Gundgurh range, and also near beree- 



ypes Sher-Shah on the Sirun river, examples may 



be found in which incipient lines of foliation cut through the rock 



and cross at an oblique angle the interbedded, more sandy, and less 



sandy layers. 



Along with the phyllites in the Gundgurh range and Tanawal come 



graphitic schists, which are a very noticeable 

 Graphitic schists. . . 



teature in the landscape, owing to the black 



carbonaceous dust into which they weather, darkening the hill-sides 



round about. The bands'generally, as in the Gundgurh range, are 



from 10 to 30 feet thick, but very impure. They are much crushed 



and contorted with quartz veins and iron staining. In the 



Black Mountain a similar band of graphitic schist gave only a 



small percentage of carbon when analysed in the Survey laboratory. 



( 53 ) 



