S8 MIDDLEMISS: GEOLOGY OF HAZARA AND BLACK MOUNTAIN. 



to the south across the Rawalpindi plateau, and hence out of the 

 limits of this Memoir. 



It will be convenient to begin with the description of zone (B), 

 because in the first place it is the most characteristic and diverse 

 in feature and formation, secondly the older geological investigators 

 began in this part of the country, and thirdly by means of it, and it 

 alone, can we be in a position to follow a description of zone (A). 



(B) The Slate Zone. 



Orography. 



The boundaries of this zone have already been defined. If the 



map be consulted it will be seen that they co- 

 General remarks. . 



incide with natural geological lines, inasmuch 



as the great schistose and gneissose area lies to the north, and the 



great Nummulitic area to the south of this zone. As the name 



implies, this block of formations is characterised by the preponderating 



presence of the Slate series. The later outcrops over a very large 



portion of it, and in many cases occupies a greater surface than 



do the younger formations of the same zone, whilst in nearly all 



cases it constitutes the lowest horizon that can be detected in the 



cores or axes of anticlinal or folded flexures. On the other hand, 



such flexures, on however grand a scale, never reveal any crystalline 



gneissose rocks below, and only in one or two limited localities have 



the lowest exposed strata assumed a slightly schistose aspect. 



It follows as a corollary to the above that the younger formations 

 present in this zone, from the Trias to the Nummulitic, are chiefly 

 found as outliers, often on the crests of ridges only, or as long thin 

 lenticular strips let in by sharp folding among the slaty basis of the 

 zone. Their extension is generally a broken one, both along the 

 strike and at right angles to it, though they are occasionally packed 

 closely together with a nearly vertical lie like books on a shelf — a 

 condition in which all traces of the original folds that brought about 

 this state are completely lost. 



The great diversity of formation in this disturbance block (which 

 ( 88 ) 



