CANADA. 341 



gneiss, and very probably greatly disturbed ; for -while the dip of the gneiss, 

 up to the immediate vicinity of the slate conglomerate, was usually at higli 

 angles, that of the latter did not exceed nine degrees, and the sandstone above 

 it was nearly horizontal. In the Report transmitted to the Canadian govern- 

 ment in 1848, on the north shore of Lake Huron, similar rocks are described as 

 constituting the group which is rendered of such economic importance, from 

 its association with copper lodes. This group consists of the same silicious 

 slates and slate conglomerates, holding peljbles of syenite instead of gneiss, 

 similar sandstones, sometimes showing ripple marks, some of the sandstones 

 pale-red green, and simiUir quartzose conglomerates, in which blood-red jasper 

 pebbles become largely mingled with those of white quartz, and in great moun- 

 tain masses predominate over them. But the series is here much intersected 

 and interstratified with greenstone trap, which was not observed on Lake 



Temiscaming The group on Lake Huron we have computed to be 



about 10,000 feet thick, and from its volume, its distinct lithological charac- 

 ter, its clearly marked date posterior to the gneiss, and its economic impor- 

 tance as a copper-bearing formation, it appears to me to require a distinct 

 appellation, and a separate color on the map. Indeed, the investigation of 

 Canadian geology could not be conveniently carried on without it. We have, 

 in consequence, given to the series the title of Huronian. A distinctive name 

 being given to this portion of the Azoic rock, renders it necessary to apply one 

 to the remaining portion. The only local one that would be appropriate in 

 Canada is that derived from the Laurentide range of mountains, which are 

 composed of it from Lake Huron to Labrador. We have, therefore, designated 

 it as the Laurentian series." (See also Canadian Journal, 1857, (2 ) II. 439- 

 442 ; Canadian Nat. and Geol., 1857, II. 255-258.) 



The logic of the last few sentences will appear to be of a somewhat 

 peculiar character, when it is remembered that the name " Laurentian " 

 had been adopted some two years before the name " Huronian " was 

 used and some four years before Mr. Logan's paper was read. 



As we have pointed out before, the age of the Lake Temiscaming 

 slates was unknown. 



In the same Proceedings Mr. Logan pvxblished a paper " On the Prob- 

 able Subdivision of the Laurentian Series of Rocks of Canada." Some 

 limestone and associated labradorite rocks he would set apart, but does 

 not pi'opose any name for them. This division seems to be a local one 

 based on lithological characters, as no evidence was advanced to show 

 that this formation was not conformable with the remainder of the 

 Laurentian, as it had been stated to be before. (Proc. Am. Assoc. Adv. 

 Sci., 1857, XL 47-51 ; Canadian Journal, 1858, (2 ) III. 1-5 ; Cana- 

 dian Nat., 1857, IL 270-274.) 



Dr. J. J. Bigsby, in 1SG2, regarded the Huronian as distinct from the 



