723 



KEPORT — 1884. 



Kori^n 



(ireuvilo Ser'r.^, 



O/.'awa Criiciss 



Qiinrtzless frranitoid or pneissoid rocks, with i)la<rioclase 

 felspars (Noriti-s) ; l(),()()l) feet. 



L.VfRKXTIAX. 



(.iranite, ■with hornhh'iiiiie gneiss, quart zite, pyroxenite, sit- 

 pentiiic, niiifrnetite, ami crvstiiUine liiuestoiie, containiiii' 

 IJoznun ; 15,000 to i'0,OUO feet. 



Granitoid {^ueis.^. 



All these nre unconformahle to each other, save perhaps the Arvonian and 

 Xorian. 



Tlie Arvonian or petrosilex group intervenes between tlie Laurentian and tlit; 

 Hmviiiian, but the peculiar ciiaracters of the Norian, and its localisation to sonii- 

 few limited areas in Europe and North America, make it ditlicult for us, as yet, 

 to define its ])reci.s9 relations to tlu; Arvonian. Tiie Norian, iiowever, pmhably 

 like tiio Arvonian, occupies a horizon between Laurentian and Iluronian. Miicii 

 time may pa.ss, and many stratigraphical studies must be made before the precise 

 relations of the Iluronian and the succeeding Montalban can he defined. It smiis 

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

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

 Notwithstanding file great geographical extent, and the importance of the.ie two 

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

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

 an event which preceded Iluronian time. 



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

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

 tiie Transition Greywacke of Eaton, which was the Upper Taconic of Ennnou?, 

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

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

 well as what lie called the Potsdam group, is tiiis same Cambrian or Traii.'sitidi: 

 Greywaclce. The Hudson liiver group also, as first described by Vanuxem ami by 

 -Mather, and later by Logan up to 1800 (when he changed its name to that of the 

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

 addition, in certain localities, of a portion of Taconian, <and in other of schistnsf 

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

 above explanation becomes necessary for the reason that the Canadian geolojiists 

 (Logan and the present writer) formerly described certain crystalline sciiist?. 

 chiefly Iluronian, as altered rocks of the Hudson Uiver group, and later (from 

 bSGO'to 1807) as of the Quebec group. 



The cupriferous series of the basin of Lake Superior (the distinctness of ■wliicli 

 was maintained by the writer in 187.'!, when he called it the Keweenaw group, n 

 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 (^lebtv 

 group. It has, however, Iwen shown by later observers that the fossilit'erou> 

 sand.^tones 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. 

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

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

 nrgillites of the Keweenian, which are interstratified with great masses of mtdii- 

 ])liyrf. are nncrystalline. It remains to be determined whether the intermediati' 

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



5. First Impressions of some Pre-Gamhrtan Bodes 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 Gecjrgian Bay, and the rocks referred to the same group in some ol 



