106 A. WINCHELL — A LAST WORD WITH THE HURONIAN. 



"The general weathered aspect is slightly greenish, but the color within is dark 

 green to gray. * * * This rock appears like the Ogishke conglomerate of Min- 

 nesota."* 



These observations were made under the impression, on the part of both 

 observers, that the two slate conglomerates were properly included in one 

 system. That prepossession removed all motive for seeking distinctions, and 

 all the more because the work was at the time casual and hurried. 



Further personal observations will be presented in separate paragraphs 

 relating to Echo lake. 



Irving' s Observations. — Professor Irving, who, as is well known, had de- 

 voted great attention to the older rocks of the northwest, was firmly per- 

 suaded of the equivalence of the typical Huronian with the Animike of Lake 

 Superior. " The whole aspect of the Huronian," he says, " as thus described 

 by Logan [in the * Geology of Canada' as quoted ante, p. 98], is strongly 

 suggestive of the Animike group of the north shore [of Lake Superior]. To 

 me it appears more than probable that the original Huronian of Lake 

 Huron and the Animike slates of Thunder bay and thence southwestward to 

 the Mississippi river are one and the same formation." f This opinion was 

 several times recorded at later dates. % 



There is reason to suppose that this identification by Irving was based 

 upon a study of the upper Huronian and not those lower slate conglomerates 

 which occupy much of the surface fifteen to twenty miles remote from the 

 shore of Lake Huron, and which, from their prominence, were always pres- 

 ent to the minds of the Canadian geologists when defining the Huronian. 

 Professor Irving, in making reference to his personal study of the original 

 Huronian, says : 



" The coast line from the Sault Ste. Marie eastward to Serpent Kiver bay was ex- 

 amined in some detail, during the summer of 1883, by myself and Assistant Geologists 

 Van Hise and Merriam, with Logan's map in hand ; while the country back from the 

 coast was traversed sufficiently to enable us to see those members of the series which 

 do not reach the coast line." ^ 



It is not stated how many miles back from the coast the explorations ex- 

 tended. The lower slate conglomerate, as here understood, is 23 miles by 

 wagon road from Thessalon. The low outcrops three to five miles back from 

 the coast, between Thessalon and Bruce, though some of them are mapped 

 by Logan as lower slate conglomerate, have, to our apprehension, the litho- 

 logical characters of the upper slate conglomerate. Hence we state that 

 Irving, in identifying the Huronian in general with the Animike, may really 



* Professor N. H. Winchell : Sixteenth Ann. Rep. Minn. Geol. Survey, 1886, pp. 30, 31. 



t Third Ann. Rep. U. S. Geol. Surv., 1883, pp. 1(54, 165. 



X Copper-bearing Rocks of Lake Superior, 1883, p. 390; Fifth Ann. Rep. U. S. Geol. Surv. 1885, pp. 

 203, 204, etc. ; Seventh Ann. Rep. U. S. Geo!. Surv., 1888, especially map plate XLI, facing p. 418; 

 Amer. Journ. Sci., 3d ser., vol. XXXIV, 1887. pp. 263, 368. 



g Fifth Ann. Rep. U. S. Geol. Surv., 1885, pp. 187, 188. 



