STRATIGRAPHICAL ELEMENTS: SLATE SERIES. II 



sombre colouring, the fineness of the sediment of which they are 

 composed, their highly fissile nature and hardness, together with the 

 fact that no other beds of slate occur subsequently among any of the 

 higher groups of strata, give to this great formation a characteristic 

 unity of aspect that marks it off completely from all the rest of the 

 formations which follow above it. In the northern parts of Hazara 

 these rocks have suffered conspicuously from dynamic and regional 

 metamorphism, and have become converted into crystalline schists, 

 just as have some of the lower members of the groups which next 

 succeed them ; but, as already stated, it will be more convenient to 

 treat all the metamorphic rocks together at the end of this chapter. 



The neutral colours of the Slate series approach most nearly to 

 dark blue-grey in tone. Some few slates are, 

 however, of an olive or greenish-grey, while 

 -occasionally they possess a purplish tinge. None of the members of 

 this series, except some among the schistose varieties where they 

 are impregnated with graphite, have a dead-black colour or anything 

 to especially indicate carbonaceous admixture. 



In composition they may be regarded as impure sandy slates 



with many interbedded bands of fine grit and 

 Composition. 



quartzite, also of dark neutral colours. Oc- 

 casionally, as south-west of Sirban hill, softer greenish micaceous and 

 earthy sandstones are regularly bedded with the slates. Here and 

 there also faint traces may be detected of a fine local conglomerate, 

 among the pebbly layers of which there are some grains of dark 

 quartzite. 



In certain areas among the Slate series there occur very subordi- 

 nate limestone bands. Abundant local sections 



Limestone interbank shew them to be tru j interbedded with the 

 ed with the slate. J 



slates, and they seem to die out in certain direc- 

 tions and in others to increase in thickness to as much as 60 or 

 80 feet. Their exact horizon among the slates is not known, inasmuch 

 as the Slate series itself is so uniform in petrological characteristics, 

 and so much disturbed and contorted, that in the absence of fossils no 



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