264 THE CANADIAN NATURALIST. [Yol. IX. 



similar to the Coldbrook, but apparently resting on the Menevian, 

 and overlaid by fossiliferous Upper Devonian beds, into which it 

 was supposed to graduate. The Bloomsbury group was there- 

 fore regarded as altered Upper Devonian, and its similarity to 

 the pre-Cambrian Coldbrook was explained by supposing both 

 groups to consist in large part of volcanic rocks. 



In 1869 and 1870, however, the writer, in company with the 

 gentlemen just named, devoted many weeks to a careful study of 

 these rocks in southern New Brunswick, when it was made 

 apparent that the Bloomsbury group was but a repetition of the 

 Coldbrook on the opposite side of a closely folded synclinal hold- 

 ing Menevian sediments. These two areas of pre-Cambrian 

 rocks were accordingly described by Messrs. Matthews and Bailey 

 in their report to the geological survey of Canada in 1871, as 

 Huronian, in which were also included the similar crystalline 

 rocks belonging to two other areas, which had been previously 

 described by the same' observers under the names of the Kingston 

 and Coastal groups, and by them regarded as respectively altered 

 Silurian and Devonian. 



After studying the Huronian rocks in southern New Bruns- 

 wick, and their continuation along the eastern coast of New 

 England, especially in Massachusetts (where, also, they are over- 

 laid by Menevian sediments), the writer in 1870, announced his 

 conclusion that the crystalline schists of these regions are lithol- 

 ogically and stratigraphically equivalent to those of the G-reen 

 Mountain rano-e of western New England and eastern Canada. 

 These, he further declared, in 1871, to be a prolongation of the 

 newer crystalline or Azoic schists of Rogers in Pennsylvania, 

 and the equivalents of the Huronian of the northwest. The 

 pre-Cambrian age of these crystalline schists in eastern Canada 

 has now been clearly proved by the presence of their fragments 

 in the fossiliferous Cambrian strata in many localities along the 

 northwestern border of the Green Mountain belt, and farther by 

 the recent stratigraphical studies of Selwyn, as announced by 

 him in 1878. 



In close association with these Huronian strata in eastern 

 Massachusetts is found a great development of petrosilex rocks, 

 generally either jaspery or porphyritic in character, and some- 

 times fissile, which, by Edward Hitchcock were regarded as 

 igneous. These were found to be identical with the rocks des- 

 ignated by Matthews and Bailey, feldspathic quartzites and 



