362 THE AZOIC SYSTEM AND ITS SUBDIVISIONS. 



twenty Tvide, stretching northeastwardly from Passamaqnoddy Bay, and 

 including the highest eminences in the southern counties, was assigned 

 to the Upper Silurian. The Bloomsbury, Little River, and Mispeck 

 groups w-ere placed iu the Middle and Upper Devonian, and were said to 

 rest unconformably upon the Laurcntian, Huronian, Lower Silurian, 

 and Upper Silurian strata, and it was stated that the Primordial shales 

 appear to overlie the Huronian without any appreciable discordance be- 

 tween the two. (Quart. Jour. Geol. Soc., 1865, XXL 422-434.) 



In Messrs. Bailey, Matthew, and Hartt's " Observations on the Geol- 

 ogy of Southern New Brunswick," 1865, a work prepared for the press 

 by Prof. Bailey, the rocks referred to the Huronian and Laurentian ages 

 are so placed on theoretical and lithological grounds. Regarding the age 

 of the Portland group, here assigned to the Laurentian, he writes : — 



" It might readily be supposed that the extreme metamorphism exhibited 

 by the rocks of the Portland Group would be accepted as conclusive evidence 

 of their great antiquity. Indeed the fact of such antiquity could scarcely 

 have been doubted, were it not for the intimate association and aliuost entire 

 conformability between the beds of this and the overlying groups, which have 

 heretofore induced all the observers who have examined the district to link 

 them in a single series. As the latter are unquestionably of Upper Devonian 

 age, the beds of Portland were supposed to represent either a portion of the 

 Lower division of the same formation, or possibly the upper part of the Silu- 

 rian." {I.e., p. 18.) 



The reasons for assigning it to the Laurentian are, in brief, partly 

 lithological, and partly because it seemed to them probable that the 

 Coldbrook group was Huronian, and therefore the syenites (Portland 

 group) must be Laurentian. {I. c, p. 18.) Between the Coldbrook 

 gi-oup and the underlying syenite and limestone. Prof. Bailey states 

 that Mr. Matthew observed " evidence of slight unconformability." 

 (l. c, p. 49.) Again he remarks : — 



" During the deposition of the various rocks referred to the Azoic and Silu- 

 rian Ages, a prolonged period of repose prevailed throughout the districts 

 where these rocks occur, broken only by the volcanic activity which marked 



the epoch of the Coldbrook Group Through all these vast intervals of 



time no evidence exists to show that any violent disturbances broke the general 

 quiet,' unless it be the folding of the Portland and Kingston rocks, and even 

 this may have been the result of a later date. Each formation was quietly 

 deposited upon that which preceded it, the almost entire conformabihty which 

 now marks their succession being conclusive evidence that no period of marked 

 upheaval prevailed between the deposits of one epoch and those of another." 

 {I. c, p. 50.) 



