[bailey] the bay of FUNDY TROUGH 109 



The northern border of the Bay of Fundy troug-h being thus tixed 

 for the early Palaeozoic with some degree of certainty, though not in the 

 position assigned to it in the manual of Prof. Dana, we have now to 

 inquire as to the corresponding border on the south. 



At the present time this southern border is, throughout its extent, 

 marked by the trappean range of the North Mountains, which cannot 

 possibly be older than the Trias, and is probably Jurassic. Eliminating 

 this and the associated red sandstones, and uniting, as would then be the 

 case, the waters of the Minas basin, Annapolis basin and St. Mary's bay 

 with those of the Bay of Fundy, we find the rocks which next border 

 the trough on the south side to be of Sihirian or Bo-Devonian age, rest- 

 ing for the greater part of their length upon the gi'anite ridge of the 

 South Mountains, the latter forming the backbone of the Nova Scotian 

 peninsula. But is the backbone Archœan ? It is so represented in Prof. 

 Dana's manual ; but it is safe to say that, as regards all that portion at 

 least of the peninsula which now lies south of the present Bay of Fundy, 

 it contains no Archaean rocks whatever. The granites were long since 

 described by Sir Wm. Dawson as being intrusive and of Devonian age, a 

 conclusion which all subsequent investigation has tended to confirm ; and 

 though both that author and Dr. Selwyn were disposed to regard the 

 horn blendic and chloritic rocks of Yarmouth as probably Huronian, there 

 is now no question that these too are really more recent, they being 

 a member, and by no means the lowest member, of the same series as the 

 gold-bearing rocks of the southern coast, usually regarded as Cambrian. 

 Thus there are no rocks, at present disclosed to view, in the portion of 

 Nova Scotia lying south of the present Bay of Fundy, which can 

 properly be pointed to as a portion of the " Acadian protaxis" ; the only 

 rocks of Archœan age to be found in the province being limited to the 

 island of Cape Breton, and possibly to some portions of the Cobequid 

 mountains. 



Before dismissing the Pre-Cambrian rocks it is interesting to note, in 

 the case of those of southern New Brunswick, the large amount of vol- 

 canic matter which they contain, and which, in the rocks referred to the 

 Huronian system alone, has been estimated to reach a thickness of 

 at least 10,000 feet. So vast an accumulation of igneous matter along 

 lines parallel with the present course of the Bay of Fundy trough, 

 not only strongly marks out the latter as a subsiding geosyncline as far 

 back as Pre-Cambrian time, but as exhibiting, even then, conditions which, 

 in later eras and in the same geosyncline, were repeated in the igneous 

 extrusions of the Silurian, the Devonian, the Lower Carboniferous and 

 the Trias. 



We have now to consider more particularly the information to be 

 obtained from the study of the Cambrian rocks. 



Sec. IV., 1897. 6. 



