15 



about N. 30 E., which is also the direction in which the 

 area is folded. They occur isolated or in linear series so 

 arranged that a very small amount of additional erosion, 

 by removing the intervening cover, would evidently con- 

 vert the series into a single, long, narrow batholith. 



Within the batholiths themselves the strike of the 

 foliation follows sweeping curves, which are usually closed 

 and centred about a certain spot in the area where the 

 foliation becomes so nearly horizontal that its direction 

 and even its existence, where the surface is level, becomes 

 difficult to recognize. From these central areas of flat- 

 lying gneiss, the dip of the gneiss (where it can be deter- 

 mined) is usually found to be outward in all directions. 

 The batholiths are, therefore, undoubtedly formed by an 

 uprising of the granite magma from below, and these foci 

 indicate the axis of the greatest upward movement. These 

 centres are not all areas of more rapid uplift. On the 

 contrary, the gneissic foliation in some cases dips inward 

 in all directions towards the centre, thus marking them 

 as places where the uprise of the magma was impeded, 

 that is to say, places where the overlying strata have 

 sagged down into the granite magma. 



If this district presents the basement of a former 

 mountain-range, now planed down, the direction of this 

 mountain range was about N. 30 E., or, in a general way, 

 parallel to the course of the valley of the St. Lawrence. 



The movements in the granite to which reference has 

 been made did not take place solely while the rock was 

 in the form of an uncrystallized or glassy magma. They 

 continued as the rock cooled and while it was filled with 

 abundant products of crystallization, the movement being 

 brought to a close only by the complete solidification of 

 the rock. Evidence of protoclastic structure can therefore 

 be seen throughout all the areas coloured as granite or 

 granite-gneiss on the map, except in the case of a few small 

 bodies of granite apparently of more recent age. This 

 protoclastic structure is marked by the presence of more 

 or less lenticular, broken fragments of large individuals of 

 the feldspar, in a fluidally-arranged mosaic of smaller 

 allotriomorphic feldspar grains with quartz strings and 

 a few biotite flakes. This fluidal arrangement, which 

 constitutes the foliation of these rocks, is seen in every 

 stage of development, there being an imperceptible grada- 

 tion from the perfectly massive forms occasionally seen, 



