Vol. 56.] THE GEOLOGY OF GILGIT. 365 



alluded to in the foregoing pages, which are also observed in the 

 gneissose granite of the Dalhousie region. I have already given 

 my reasons * for believing these structures to have been produced 

 by traction at the time of intrusion and by shearing and pressure, 

 operating on the rock duriug its gradual cooling and progress from 

 a viscid to crystalline condition. I have seen nothing in my study 

 of the Gilgit rocks to modify that opinion. 



In the foregoing pages I have given abundant details of dynamic 

 action on the rocks of the Gilgit area, and in particular have noted 

 cases in which granite has been shattered or sheared into shreds, 

 and I am willing to believe that in these cases the shearing may 

 have taken place after the consolidation of the rock. When, however, 

 we are dealing with structures which are not limited to thin sheets, 

 or dykes, but permeate granite-masses 10 to 12 miles thick, the 

 application of the shearing-after-consolidation theory to explain 

 those structures becomes to my mind unreasonable. 



In the Gilgit area shearing seems to have been quite local, and 

 confined to the immediate neighbourhood of thrust-planes and 

 faults. For instance, granite-sills and veins in the Gaisheli Cliff 

 have been sheared into lenticular strips of quartz and felspar, while 

 the Hatu Pir Granite hard by (at Gich) does not show any parallelism 

 of structure. Either the Hatu Pir Granite was intruded after the 

 shearing had ceased, or, far more probably, the thrust-plane which 

 caught the granite in the Gaisheli Cliff passed clear of the granite 

 at Gich. 



I shall not attempt to go over old ground, but before leaving the 

 subject of structures in granite, such as tessellated quartz, it may 

 be as well to give an illustration from the Gilgit rocks. At Lecher 

 the Hatu Pir Granite is cut through by a pyroxenite, and both are 

 traversed diagonally by the Askurdas Muscovite-Granite. The 

 Hatu Pir Granite shows some ordinary parallelism of structure. 

 The pyroxenite exhibits none whatever, but in the last invader the 

 quartz is tessellated and drawn out into strings. Is it probable, I 

 would ask, that the dynamic force which impressed itself so deeply 

 on the last intruder can have been applied to this igneous complex 

 after its consolidation ? If it was so applied, is it conceivable that 

 it should have left the pyroxenite unsheared, unfoliated, unfaulted, 

 and without a trace of parallelism of structure? According to my 

 theory, the case presents no difficulty. The Hatu Pir Granite had 

 a slight parallelism of structure imparted to its biotite by pressure 

 when it was in aplastic condition. The pyroxenite crystallized in 

 tranquil times. The Askurdas Granite welled up into a fissure, the 

 walls of the fissure were moved up and down, and the granite was 

 squeezed between them when approaching consolidation. 



The Gilgit granites abound with examples of the solvent action 



1 A summary account of these structures and of my views regarding them 

 will be found in my Presidential address to the Geologists' Association *Proc, 

 G. A. vol. xiv (1896) p. 287. 



Q. J. G. S. No. 222. 2 c 



