﻿1851.] 



STRACHEY GEOLOGY OP THE HIMALAYA. 



309 



The general extension of the Chain along the direction of the strike 

 of the strata, is a phsenomenon necessarily connected with the action 

 of an upheaving force along a line. 



This longitudinal action is further evinced by the parallelism of the 

 lines of eruptive action with that of the strike. 



The continuance of the action of the upheaving forces along the 

 same general line for a vast period of time, with occasional intervals 

 of repose or of subsidence, is indicated along both the north and south 

 faces of the Himalaya. The great depth at which the forces have 

 originated seems to be proved by the regularity of the action along 

 the entire length of the chain, as shown by the elevation of such a 

 ridge as the Siwalik Hills. 



The Granites appear to constitute lines of elevation, not of rupture ; 

 but there seems to be no specific action produced by them on the 

 dip of the strata, which they appear to leave generally unchanged. 



The Greenstones, on the other hand, usually follow lines of disloca- 

 tion of the strata ; being sometimes apparently contemporaneous, and 

 at others intruded through rocks already consolidated. 



The cause of the general north-easterly direction of the dip is ob- 

 scure, although its occasional sudden reversal to south-westerly seems 

 to indicate some connexion with the action of an upheaving force 

 from below, or of violent lateral thrust. 



The lines of fracture of the strata are constantly either parallel or 

 perpendicular to the direction of the upheaving force. 



The positions of the rivers appear to be altogether dependent on 

 the configuration of surface produced by these fractures ; while the 

 configuration of surface, on the other hand, seems to be but slightly 

 affected by the action of the streams, of which there is rarely any 

 visible sign at 200 feet above the present level of the waters, and 

 never to my knowledge above 300 feet. 



The fact of the granite of the great snowy peaks being seen in 

 veins, penetrating the schists up to 20,000 feet, makes it highly pro- 

 bable that the granite must have been injected long before the moun- 

 tains received any considerable development. 



That this granite is older than the Silurian period is rendered pro- 

 bable by the comparatively unaltered state of the lower beds of the 

 Azoic slates at the foot of the Palaeozoic series, where almost in con- 

 tact with it. 



The conglomerate bed near the bottom of these same Azoic slates 

 shows the proximity of land at the time of its deposit, and indicates 

 that some upheaval of land had already taken place near the present 

 line of great peaks, possibly occasioned by the granite in question. 



The occurrence of pebbles of greenstone in the sandstones, supposed 

 to be secondary, along the southern edge of the mountains, shows 

 that the exterior lines of greenstone are older than those beds of 

 sandstone. 



The frequent occurrence of boulders of the quartzites, slates, and 

 greenstones of the outer ranges of mountains among the tertiary 

 deposits of the Siwalik Hills, shows that the Tertiary ocean washed 

 the foot of those mountains. 



