No. 5.] HUNT — PRE-CAMBRIAN ROCKS. 263 



by Logan, and by the present writer. The belt of micaceous, 

 chloritic, talcose and epidotic schists, with greenstones and ser- 

 pentines, the extension of a part of the Azoic of Rogers, which, 

 through western New Eugland, is traced into Canada, (where it 

 has been known as the Green Mountain range), was previous to 

 1862 called by the geological survey of Canada, Altered Hudson- 

 River group. It was subsequently referred to the Upper Taconic 

 of Emmons, to which Logan, at that date, gave the name of the 

 Quebec group, assigning it, as had long before been done by 

 Emmons (in 1846) to a horizon between the Potsdam and the 

 Trenton of the New York system. 



In 1862 and 1863 appeared, independently, two important 

 papers bearing on the question before us as to the age of these 

 rocks. The first of these was by Thomas Macfarlane, who, after 

 a personal examination of the three regions, compared the Huro- 

 nian of Lake Huron and the Green Mountain range of Canada, 

 with portions of the Urschiefer or Primitive schists which, in 

 Norway, intervene between the ancient gneisses and the oldest 

 Paleozoic (Lower Cambrian) strata. The second paper was by 

 Bigsby, who was, as we have seen, the earliest student of the 

 Huronian in the northwest, pointing out that these rocks could 

 not in any sense be called Cambrian, but were the equivalents of 

 the Norwegian Urschiefer. The conclusions of Macfarlane were 

 noticed in connection with the views of Keilhau on these rocks 

 of Norway in "The Geology of Canada" in 1863, with farther 

 comparisons between the New England crystalline schists and 

 the Huronian, but official reasons then, and for some years after, 

 prevented the writer from expressing any dissent from the views 

 of the director of the geological survey of Canada. 



Meanwhile, the existence of an equivalent series of crystalline 

 schists was being made known in southern New Brunswick, where 

 they were described by G. F. Matthews in 1863, under the name 

 Coldbrook group, which included a lower and an upper division. 

 In a joint report of Matthews and Bailey in 1865, these rocks 

 were declared to be overlaid unconformably by the slates in which 

 Hartt had made known a Lower Cambrian (Menevian) fauna, 

 and were compared with the Huronian of Canada. The lower 

 division of the Coldbrook was then described as including a 

 large amount of pink feldspathic quartzite and of bluish and 

 reddish porphyritio slates. In the same report was described, 

 under the name of the Bloomsbury group, a series lithologically 



