ROCKS OF THE ATLANTIC COAST OF CANADA, ETC. 803 



contain *. I confess, however, that I am inclined to suspect that 

 some of the beds known as Ainimike and Taconian may prove to be 

 of this character, as well as some of the disputed Huronian of the 

 Appalachian region f. 



The second question relates to the extent to which conditions 

 similar to those of the Huronian may have been repeated in subse- 

 quent periods ; and here it is evident that wherever on continental 

 margins coarse aqueous rocks were being accumulated, in the 

 vicinity of igneous foci and mixed with their detritus, rocks litho- 

 logically resembling the Huronian may have been dex)osited. This 

 consideration imposes much caution as to the possible correlation of 

 such deposits with the true Huronian on the ground of mineral 

 character alone. In Nova Scotia and New Brunswick as well as in 

 Great Britian there are rocks having in many respects the aspect 

 of the Huronian which belong to PaliEOZoic times, and there is reason 

 to believe that on the Pacific coast there are certain rocks of this 

 kind of much later date. These, as has been shown by Dr. Selwyn 

 and Dr. G. M. Dawson, are in great part bedded volcanic ash-rocks 

 in an altered condition J. 



An important new light has recently been thrown on the supposed 

 upper Huronian of Newfoundland by Mr. Matthew, who has found 

 that in New Brunswick the conglomerate and red sandstone under- 

 lying the Pm'ado.vides-beds are, as before stated, unconformable to 

 these, and that, like the Basal or Caerfai beds of Hicks in Wales, which 

 somewhat resemble them in mineral character, they contain worm- 

 tracks and a Linguloid shell as well as remains of Algae. He there- 

 fore regards these as basal Cambrian beds. This may also prove to 

 he the position of the Newfoundland Signal-Hill rocks, and of the 

 Kewenian series of the west. This basal series of New Brunswick 

 is estimated at 1200 feet in thickness. If it be reckoned as the 

 equivalent of the Caerfai, the lower members of the St. John group 

 proper will be the equivalent of the Solva group, and the upper 

 members will represent the Menevian §. In a letter recently received 

 from Mr. Irving, of the U. S. Geological Survey, he informs me that 

 " an obscure Linguloid shell " has been found in the quartzite of 

 south-western Minnesota, a formation which he regards as probably 

 below the Kewenian, and possibly even Huronian, These facts 

 render it possible that an upper Huronian series containing precursors 

 of the Cambrian fauna may jet be recognized, or probably a new 

 intermediate system to be designated by some other name i|. It will 

 also be observed that, like the typical Huronian, such series, whether 



* I find such indications in the chert of the limestones on Greorgian Bay. 

 They are apparently simple acerate siliceous spicules, resembhng those of some 

 Cambrian sponges. 



f See, however. Dr. Sterry Hunt," Elements of Primary Geology," Geol. Mag., 

 Nov. 1887, for his classification of the western rocks of these groups. 



X Eeport Geol. Survey of Canada, 1871-1885. 



§ Matthew, ' Canadian Record of Science,' 1887. 



II Irving has proposed tO call all the formations between the Laurentian and the 

 base of the Cambrian " Agnotozoic ; " but the term Huronian seems sufficient at 

 present for this purpose. 



