728 eeport— 1884. 



Korian . . . Quartzless granitoid or gneissoid rocks, with plagioclase 

 felspars (Norites) ; 10,000 feet. 



Latjrextian. 



Grenville Series. Granite, with hornblendic gneiss, quartzite, pyroxenite, ser- 

 pentine, magnetite, and crystalline limestone, containing 

 Eozoon ; 15,000 to ->0,000 feet. 



Otfaica Gneiss . Granitoid gneiss. 



All these are unconformable to each other, save perhaps the Arvonian and 

 Norian. 



The Arvonian or petrosilex group intervenes between the Laurentian and the 

 Huronian, but the peculiar characters of the Norian, and its localisation to some 

 few limited areas in Europe and North America, make it difficult for us, as jet, 

 to define its precise relations to the Arvonian. The Norian, however, probably 

 like the Arvonian, occupies a horizon between Laurentian and Huronian. Much 

 time may pass, and many stratigraphical studies must be made before the precise 

 relations of the Huronian and the succeeding Montalban can be defined. It seems 

 probable, in the present state of our knowledge, that the Montalban series was, in 

 many cases, deposited over areas where the Huronian had never been laid down. 

 Notwithstanding the great geographical extent, and the importance of these two 

 series, neither can claim that universality which probably belonged to the primitive 

 granitic substratum, a universality soon interrupted by the appearance of dry land ; 

 an event which preceded Huronian time. 



The author sketched the history of opinion regarding the relations of the lower 

 Palaeozoic to the Eozoic rocks ; he stated that recent researches have shown that 

 the Transition Greywacke of Eaton, which was the Upper Taconic of Emmons, 

 and includes the primordial or Cambrian fauna, rests in unconformable stratifica- 

 tion upon the various crystalline Eozoic rocks. The Quebec group of Logan, as 

 well as what he called the Potsdam group, is this same Cambrian or Transition 

 Greywacke. The Hudson River group also, as first described by Vanuxein and by 

 Mather, and later by Logan up to 1860 (when he changed its name to that of the 

 Quebec group) is nothing else than this same Cambrian Greywacke, with the 

 addition, in certain localities, of a portion of Taconian, and in other of schistose 

 beds containing the second or Ordovician fauna (Utica and Loraine shales). The 

 above explanation becomes necessary for the reason that the Canadian geologists 

 (Logan and the present writer) formerly described certain crystalline schists, 

 chiefly Huronian, as altered rocks of the Hudson River group, and later (from 

 1860 to 1867) as of the Quebec group. 



The cupriferous series of the basin of Lake Superior (the distinctness of which 

 was maintained by the writer in 1873, when he called it the Keweenaw group, a 

 name which he subsequently changed to Keweenian), which has a thickness pro- 

 bably greatly exceeding 20,000 feet, was also by Logan referred to the Quebec 

 group. It has, however, been shown by later observers that the fossiliferous 

 sandstones which rest in horizontal layers upon the inclined strata of the Keweenian, 

 belong to the Cambrian, and hold the fauna of the Potsdam. The conglomerates 

 of the Keweenian cupriferous series contain portions alike of Laurentian Arvonian, 

 Huronian, and Montalban rocks, and appear, according to the latest observations, 

 to overlie the schists which we have referred to the Taconian. The sandstones and 

 argillites of the Keweenian, which are interstratified with great masses of mela- 

 phyre, are uncrystalline. It remains to be determined whether the intermediate 

 Keweenian series has greater affinities with the Taconian than with the Cambrian. 



5. First Impressions of some Pre-Cambrian Rocks of Canada. 

 By Professor J. F. Blake, M.A., F.G.S. 



The author had examined the Huronian rocks in their typical locality on the 

 north shore of Georgian Bay, and the rocks referred to the same group in some of 



