Lawson.] 



The Eparchcean Interval. 



57 



is inconsistent with the same term in the narrow and emasculated 

 sense to which it is proposed to restrict it. 



The obscuration of the importance of the Eparchsean Inter- 

 val has been promoted further by certain erroneous correlations 

 in the Lake Superior province. Nothing could be clearer in 

 stratigraphy than the unconformable superposition of the 

 Animikie of the Thunder Bay District upon the Archaean com- 

 plex, including- the Keewatin invaded by granite-gneiss. Yet 

 the Animikie series was correlated before the invention of the 

 term Algonkian both with the Keewatin schists to the west of 

 Lake Superior and with the Huronian of Lake Huron. Both of 

 these correlations were, in the opinion of the writer, errors; and 

 they were the forerunners of a fundamental misconception of 

 Lake Superior geology which persists to tins day, and which has 

 become entrenched chiefly owing to the extraordinary use to 

 which the term Algonkian has been put. The correlation of the 

 Animikie with the Keewatin schists west of Lake Superior 

 would probably not be urged to-day, but the correlation of the 

 Animikie with the (Upper) Huronian is still a living doctrine, 

 upon which is based the whole scheme of nomenclature of the 

 rock series of the south shore. Its vitality is, however, no proof 

 of its truth, and I entertain no doubt whatever but that scheme 

 of nomenclature must undergo radical revision in the near future. 



This correlation of the Animikie with the Upper Huronian, 

 made as it was in connection with the correlation of the same 

 series with the Keewatin schists to the west, indicates an entire 

 lack of appreciation of the significance and importance of the 

 Eparchaean Interval. The correlation was avowedly made on 

 petrographical grounds. This being the case we might reason- 

 ably expect a close parallelism between the Animikie rocks and 

 those of Lake Huron. No such parallelism exists. Several 

 hundred feet of carbonaceous shales constitute the most charac- 

 teristic stratigraphic feature of the Animikie. These shales are 

 absent from the Huronian (Upper) of Lake Huron. Limestones 

 are practically absent from the Animikie. They occur at several 

 horizons in the Huronian of Lake Huron. There are no vol- 

 canics in the Animikie of Thunder Bay, while they occur in the 

 Huronian. The characteristic "slate conglomerate" of the 



