NEW BRUNSWICK. 577 



which I would therefore be inclined to refer your rocks, though I 

 would not affirm that they may not include Lower Devonian, which 

 in Nova Scotia are altered with the Upper Silurian. 



" I regard your specimens as altered sediments, though some of the 

 felspathic and hornblendic ones may be true Plutonic rocks." 



(2.) Mr Matthew has found, in loose fragments, near St John, pro- 

 bably derived from these rocks, the following fossils : — Chonetes, 

 Pterinea or Avicida, Clidophorus, Orthis, Rhynchonella (?), Leptodo- 

 mus (?), etc. ; and still more recently specimens have been obtained 

 from undoubted members of the Kingston group, in which the follow- 

 ing characteristic Upper Silurian assemblage of genera occurs, though 

 in a state too imperfect for specific determination. 



The genera are Dalmania, Phacops, Orthoceras (2 species), Murchi- 

 sonia (2 species), Loxonema, Holopea (?), Lucina (?) or Anatina (?), 

 Avicula (?), Leptodomus (?), Spirifer, Chonetes (?), Ah-ypa, Rhyn- 

 chonella (?), Retzia (?), Strophomena^ Orthis, Discina, Favosiies, 

 Zaphrentis (2 species), Syringopora (?), and other corals. From 

 Frye's Island also, in the south-western extension of these rocks, 

 Upper Silurian fossils have been obtained. 



(3.) A comparison of these rocks with those in Maine, in their line 

 of strike, and ascertained by Hitchcock to be Upper Silurian, confirms 

 the above evidence from mineral character and fossils. 



One source of perplexity in the determination of these rocks arises 

 from the fact that, in the vicinity of St John, the Devonian rests on 

 the Lower Silurian without the intervention of Upper Silurian beds. 

 This, as Mr Matthew suggests, may be accounted for by denudation, 

 or by the elevation of the Lower series before the deposition of the 

 Upper. In Maine, however, it would seem that these rocks appear in 

 their regular sequence below the Devonian. 



It will be observed that, as in Nova Scotia, the Upper Silurian 

 sediments are more argillaceous and less calcareous than the beds of 

 this age in the more inland parts of the continent, and that they are 

 also much more metamorphosed. In both of these particulars we shall 

 find a decided difference in the Upper Silurian of Northern New 

 Brunswick, next to be noticed. 



A glance at the map will enable the reader to perceive, extending 

 south-west from Bathurst, in the Bay de Chaleur, that broad and 

 rugged belt of altered Lower Silurian and Plutonic rocks, the terror 

 of railway engineers, which forms the natural limit of Acadia on tlie 

 north-west, and separates the Coal-fickl of New Brunswick from tlie 

 Upper Silurian valley of the Rcstigouche and Upper St John, the debate- 

 able land, in point of physical geography, between the high lands of 



2 !• 



