ATLANTIC COAST OF NOVA SCOTIA. 621 



detailed lines of section should be run across tlie district at several 

 places, and some of the more decided outcrops of quartz rock should 

 be carefully traced. 



It is interesting to note the points of difference between these rocks 

 and the more highly altered portions of the Upper Silurian series, as 

 described in a previous chapter. Quartz rock occurs in both ; but 

 it exists in greater abundance and in more massive beds in that last 

 described. Clay-slate also occurs in both, but in the first described 

 it presents much greater variety of colour and texture ; it is associated 

 with many coarse beds, which have been usually named graywacke, 

 and graywacke slates, and in many places it approaches to the char- 

 acter of a steatitic slate. These iidand slates are also highly metal- 

 liferous, abounding in veins of iron ore, and containing at least one 

 great conformable bed of that mineral, while copper ores also appear 

 in a variety of places. They also contain numerous calcareous bands 

 and layers of limestone. In all these respects the slates of the 

 Atlantic metamorphic district are strikingly different. They are 

 thick-bedded and uniform in their appearance, destitute of calcareous 

 matter, and with few metallic minerals, except disseminated crystals 

 of iron pyrites, and the veins of auriferous quartz, which are nearly if 

 not altogether peculiar to this formation as compared with the other. 

 They also pass into micaceous slate, which is rarely seen in the other 

 district. These and other differences of detail must prevent any 

 observer acquainted with both districts from supposing their rocks to 

 be geologically equivalent. 



The metamorphism of these rocks must have occurred prior to 

 the Carboniferous period, and there can be no doubt that the granitic 

 rocks have been the agents in affecting it, if they are not themselves 

 portions of the stratified beds completely molten and forced by 

 pressure against and into the fissures of the neighbouring itnmelted 

 rocks. It will be observed that many of these granitic masses 

 have a north and south direction, whereas the general strike of 

 the beds is N.E. and S.W. This would indicate either that the 

 lines of greatest igneous intensity and intrusion of molten matter 

 had no direct connexion with the elevating and disturbing forces, 

 or that these granitic masses are merely outliers from a great N. E. 

 and S.W. granitic axis, at one time the summit of a line of hills 

 of which only the margin remains visible, the axis itself having 

 sunk again into the bowels of the earth, before the commencement 

 of the Carboniferous period. 



The general direction of the strike of this district coincides with 

 that of the Lower Silurian bands of New Brunswick and of the Lower 



