THE LOWER SILURIAN. 81 



If the above views are correct, it will follow that in the Lower 

 Silurian period the area of Nova Scotia and New Brunswick was the 

 theatre of extensive and long-continued volcanic ejections, producing 

 a series of rocks entirely dissimilar from those deposited at the same 

 period in the interior continental region, though in some respects 

 resembling those of Great Britain and those of the regions in Quebec 

 and the United States lying east of the great Appalachian line of 

 disturbance. 



11. THE CAMBRIAN. 



Under this head I would now place the interesting "Acadian 

 series" of St John, so well characterized by its fauna, that it may be 

 considered as the typical representative in Eastern America of that 

 Middle or LoAver Cambrian formation known in England as the 

 Menevian, and of Barrande's etage C of the Primordial in Bohemia. 

 The true horizon of these beds was, of course, perfectly recognised at 

 the time of the publication of my last edition, but they were then, 

 in accordance with prevailing classification, placed as Pi'imordial 

 Silurian. Nothing new can as yet be added to the almost exhaustive 

 examination of their fossils at that time made by Professor Hartt, 

 nor has the area of beds holding these fossils in the Acadian Pro- 

 vinces been considerably extended.* lu Newfoundland-}- and New 

 England, however, beds of this age seem to have a large extension ; 

 and in certain conglomerates of the Quebec group on the Lower St 

 Lawrence there are fragments holding the remains of a fauna Avhich 

 has been termed by Billings Lower Potsdam, and must be near to 

 the age of the Acadian group. 



The great Atlantic coast series of Nova Scotia, Avhich is the 

 auriferous formation of that province, and includes in ascending 

 order the so-called Quartzite and Clay-slate formations, in which 

 these rocks respectively predominate, I believe to be likewise Cam- 

 brian or Primordial, a view which Mr Selwyn and Professor Hind 

 have also advocated. It is, however, noteworthy that in mineral 

 character this very widely extended formation does not precisely 

 resemble the Acadian series of New Brunswick, and it is therefore 

 to be presumed that it represents some other part of that great 

 system of formations. 



The evidence of fossils in determining the precise age of these 

 rocks is unfortunately as yet somewhat imperfect. Mr Selwyn has 

 recognised in the Slate formation at Lunenburg linear markings of 



* Note VI. t Murray's Reports and Map. 



