72 MIDDLEMISS: GEOLOGY OF HAZARA AND BLACK MOUNTAIN. 



shews large felspars with apparently microperthitic intergrowths. 

 The quartz, as usual in most of these rocks, shews evidence of crush- 

 ing with production of polysynthetic aggregates. 



No. sfp Shal N. between Kand and Seri, Black Mountain. 

 A porphyritic-augen and lenticular-tabular variety. In the hand- 

 specimen this rock is a beautiful example of the so-called 'flaser' 

 type of deformation of a rock by enormous pressure, which has been 

 sufficient to cause the various constituents of the rock to, as it were, 

 flow like a semi-liquid body. I can conceive of no other cause than 

 intense pressure, exerted in three directions, and greater in one than 

 in the other two, to have produced such a rock. 



I give below (fig. 3) a rough outline sketch of the rock fragment 

 which, poor as the drawing is, speaks for itself. In the lower portion 

 of the right-hand side of the block there are two large eyes of felspar 

 considerably deformed by pressure, and with the rest 'of the fine 

 material of the rock flowing round them, as it were. At the top of the 

 specimen there is a great tabular layer of felspar which represents 

 probably several porphyritic crystals of felspar which have been 

 welded together by the rolling-out process, just as in the familiar 



illustration of a layer of 

 pastry. The finer material 

 of the rock also shews 

 numerous beautiful exam- 

 ples of eye structure on a 

 small scale. 



Seen under the micro- 

 Fig. 3, No. tIt. aa.~felspar eyes and layers, scope the felspars are 

 water-clear and cannot be distinguished from the quartz, except 

 by the needle-like inclusions which they contain, by their occa- 

 sional binary twins, and by the microcline-like plaid appearance 

 of the grains. Of original crystal outline there is none left. The 

 felspathic material, which swells out here and there into lenticles 

 With nodes between, shews by its undulating boundaries how 

 intense was the deformation it sustained. Between crossed nicols 



( 72 ) 



