DESCRIPTIVE GEOLOGY: GENERAL CONSIDERATIONS. 2$l 



and folding) of the rocks having taken place subsequently to the 

 carving out of the main river and stream beds, under which condi- 

 tions the continuous zone of rock below and about the level of erosion 

 would, of course, be thrown into folds, whereas the discontinuous hill- 

 masses above would instead be simply brought nearer to one another 

 as wholes without any, or at least so great, plication as took place 

 below. 



I cannot say that I have ever seen anything to prove such an 

 hypothesis: but on the contrary, in Hazara at least, we possess clear 

 proofs from the presence of horizontal gravels at all heights from 

 1,000 feet to 6,000 feet in the gorges and river valleys, and some- 

 times forming wide plateaux as at Hureepore, Abbottabad, and Man- 

 sehruh, that no such action has gone on so far back in the recent 

 erosion of those gorges and valleys as is indicated by these grave 

 banks. 



A more probable reason in part I think to be the following : In 

 •traversing across, for instance, the southern part of the crystalline 

 and metamorphic zone in a northerly direction, we pass from that 

 part of the zone where the more visible effects of disturbance are 

 manifest to that part where, owing to the resistance of the granite 

 cores, the effects are confined to the minuter particles of the 

 rock, as referred to under the last marginal heading. Another 

 reason may be the superficial one already alluded to in the Dore 

 R. (see p. 140) explicable as follows: — The recent elevation of 

 Hazara (proved by the high level gravels) naturally brought 

 about a commensurate deep cutting of the valleys in their lower 

 parts producing great convex slopes steepening below. Such 

 slopes are always unstable, especially along the lines of junction 

 between rocks of different composition and massiveness, and hence 

 the lower parts of such slopes offer all facilities for surface slipping 

 and surface flexure on a large scale, producing an apparent 

 greatly contorted state of the rocks. To such causes I believe to be 

 due many of the subsidiary folds of the rocks borne on the larger 

 folds. Such action may otherwise be regarded as a sort of * settling ' 



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