52 MIDDLEMISS: GEOLOGY OF HAZARA AND BLACK MOUNTAIN. 



disintegrated appearance. The new forces, which have come into play- 

 as part of the metamorphism, have not gone sufficiently far to give 

 the rock a thoroughly crystalline structure, whereas they have gone 

 far enough to destroy the previous coherence of the rock along its 

 original planes of bedding. As a consequence of this, the great 

 expanse of slightly schistose rocks, which forms much of the country 

 around Mansehruh, is in a rapid state of disintegration by weather- 

 ing and river action : the rock powders up at the surface into a 

 soft micaceous sand which can be dug with a spade. 



Under this heading I include a great many pale-grey or brownish 



fine-grained sandy rocks, which shew every 

 Arenaceous schists. .... f . . . . . .. . . 



indication of having been originally formed as 



ordinary sediment. In most cases the original planes of bedding are 

 quite discernible, being indeed more easily detected than the sub- 

 sequently induced foliation. The angle between the planes of folia- 

 tion and the bedding planes are quite irregular ; the one may be 

 nearly coincident with the other, or it may be (as in a specimen 

 | mile north-east of Mansehruh) exactly at right angles to it. The 

 above specimen shews a perfect banding of differently coloured sedi- 

 mentary material, the bands running in sharp straight lines just as the 

 bedding planes do in a fine grit. False-bedding on a fine scale is 

 also discernible. The foliation planes, on the other hand, cut across 

 these at right angles and undulate gently. The rock tends to break 

 along the latter, revealing feebly glistening surfaces of mica. 



A specimen of mica-schist taken | mile north-east of Mansehruh, 

 No. ~ 3 l i shews, under the microscope and also in the hand specimen, 

 a very marked instance of what I have called elsewhere lenticular- 

 tabular foliation on a fine scale. The quartz-grains have become 

 elongated or rolled out under pressure into lens-shaped bodies or 

 minute eyes connected one with another. Between the waving 

 layers development of mica has gone on to a considerable extent. 

 The magnetite in many places has been drawn out parallel to the 



' The numbers here and elsewhere are the numbers of the specimens given in the 

 Geological Survey Rock Register. 



( 52 ) 



