THE nURONIAN. 31 



must have existed ; but to what an extent arc they known to us ? 

 The limestones associated with the Iluronian probably belong to 

 their margins ; but these have so far afforded no fossils except ob- 

 scure indications of sponge-spicules in the chert-nodules which they 

 contain.* Those, which seem to be simple spicules, would indicate 

 at least sponges as inhabitants of the Iluronian sea. It is ju.st pos- 

 sible that some foi'tunate discovery of deep-water deposits of this 

 age may yet be made ; but if so, they will certainly be different in 

 mineral character from the typical Iluronian, and so may for a time 

 fail to be identified with it. 



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 char- 

 acter, as well as some of the disputed Huronian of the Appalachian 

 region. ■{- 



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 focci and mixed with their detritus, rocks lithologically 

 resembling the Huronian may have been deposited. This considera- 

 tion 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 

 Britain, there are rocks having in many respects the aspect of the 

 Huronian which belong to Pal£eozoic 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. | 



An important new light has, as already stated, been thrown on the 

 supposed Upper Iluronian of Newfoundland by Mr Matthew, who has 

 found that in New Brunswick the conglomerate and red sandstone 

 underlying the Paradox ides-hcds 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 

 Lower Cambrian fossils. He therefore regards these as basal Cam- 

 brian beds. This may also prove to be the position of the New- 



* I have found such indications in tlic chert of the limestones on Geori;ian Hay. 

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

 Cambrian sponges. Journal Geol. Society, Nov. 1888. 



t See, however, Dr Stcrry Hunt, " Elements of Primary Geology," Geol. Mag., 

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



t Report Geol. Survey of Canada. 1871-188.5. 



