62 BAILEY ON GEOLOGY OP 



designated as mica schist, while the other, forming the centre of a synclinal, was desig- 

 nated simply as clay slate. The division in New Brunswick was similar, but in connection 

 with both groups, fossils were obtained, those connected with the former, which was 

 described as the " Dark Argillite Series," indicating a Silurian horizon, while those of the 

 latter, though obscure, favored the supposition that they were Devonian. This latter view 

 also received coulirmation from the fact that these rocks would thus be occupying their 

 natural position directly beneath the Carboniferous system, around both margins of which- 

 they come to the surface. No reason for doubting this determinatioD, as regards the Devon- 

 ian, has since arisen, but as regards the so-called dark argillites, while at first the view 

 was entertained that tln'y were wholly Upper Silurian, a question subsecjueutly arose as to 

 whether they might not also embrace still older or Cambro-Silurian strata. The rocks with 

 reference to which, more particularly, this latter view was held are those which cross St. 

 Croix River, north of Baring, and thence extend easterly through the parish of St. Stephen, 

 in New Brunswick, to and beyond the settlement of Moore's Mills, consisting chiefly of 

 fine-grained gneisses, micaceous, garnetiferous and staurolitic slates, black plumbaginous 

 schists, actinolyte schists and purple fine-grained micaceous sandstones ; but eventually 

 the same view was extended to the whole of the " dark argillite " series, except such 

 portions as could be clearly shown, upon palœontological evidence, to be Silurian. It was, 

 however, at the same time stated that this arrangement was provisional, and it is still 

 uncertain how much, if any, of the formation in cjuestion can really be regarded as older 

 than the system last named. The facts which favor the general Upper Silurian age of the 

 belt are those of its position directly beneath and in apparent conformity to the " pale 

 argillites " or Devonian (the contacts, however, being vertical), and of a general resem- 

 blance, which it bears to the first-named group of rocks, as developed in some portions of 

 King's County, New Brunswick, and around Passamaquoddy Bay. On the other hand, the 

 resemblance to the rocks which occupy a similar position on either side of the northern 

 granite axis is still more marked; while in this latter case, it has not only been shown that 

 the argillites in question are unconformably covered by fossiliferous Upper Silurian beds, 

 but in places themselves contain fossils indicative of a Lower Silurian horizon. That the 

 rocks of these several dark argillite belts, as seen (1) north of Baring and St. Stephen, (2) 

 through the x^arish of Prince William, and (3) in Canterbury, New Brunswick, are essen- 

 tially alike, would probably be readily admitted by any one who directly compared them, 

 and the view that they are the same formation brought up by successive geanticlinals has 

 been taken alike by Gresner, Robb, Hitchcock, Hind, Logan, Ells and the present author. 

 All these authorities have also regarded them in the main as older than Silitrian, the two 

 authorities first named considering them (together with the pale argillites or Devonian) as 

 of Cambrian age, while by Hind and Logan they havi* been compared to the so-called 

 Quebec Group. It should not however, be overlooked that at one point in New Brunswick 

 (Rocky Brook, on Nashvvaak River) in the very heart of the dark argillite belt, and at but 

 a short distance from the granite, fossils indicative of a Lower Helderberg horizon were, 

 some years ago, found by the late Chas. Robb, and more recently, in the same belt, but in 

 its less altered portions, fossils which appear to be of Devonian type have been obtained, 

 a few miles north of Fredericton, by Mr. W. T. H. Reed. Hence the same question arises, 

 here as nearer the coast, whether, upon the evidence of these fossils, the age which they 

 indicate is to be regarded as that of the entire belt in which they are obtained, or of any 



