On the Norian or "Upper Laurentian" Formation. 287 



shoot everywhere more or less distinctly foliated, as the 

 bisilicates and the iron ores are arranged in more or less 

 distinct parallel streaks or strings (Figs. 6 and 7). The 



latter are evidently 

 nothing else than the 

 rounded spots rich in 

 bisilicates which are 

 shown in fig. 1, which, 

 however, are drawn 

 out by a movement 

 in the rock. The 

 fragments of plagio- 

 , distinguished by the 



Fig. 6. 



clase and the portions of the rock 

 difference in their size of grain, are likewise arranged in 

 the same direction. We most clearly see this foliation 

 where the bisilicate and iron ores are comparatively abun- 

 dant. In places where these ingredients are wanting, as 

 is often the case, and where the rock presents an almost 



even size of grain, it 



resembles a white 

 marble and no traces 

 of foliature can be 

 seen even in a wea- 

 thered surface. In 

 general, however, the 

 foliation is quite dis- 

 | tinct, and runs paral- 

 F»e 7 lei to the longer di- 



rection of the arm, that is to say, to the strike of the 

 gneiss. Like the gneiss itself, the apophysis dips towards 

 the west and is therefore overlain on the west side by the 

 gneiss, but the angle of the dip is very different in 

 different places. In some places it is almost horizontal, 

 in others it dips at high angle. Along the western limit 

 of the arm the strike is very regular and uncommonly 

 well developed. It is well seen near New Glasgow, but it 



