26 THE CANADIAN NATURALIST. [Yol. ix. 



associated dioritic, micaceous, slaty and conglomerate rocks, were 

 a newer series than those already examined and described by 

 Sir W. E. Logan, and they were accordingly designated, in the 

 report published in 1870, the Hastings series, and it was further 

 supposed, from its apparent stratigraphical position and from 

 certain lithological resemblances, that it might be of Huronian 

 age. The gradual progress of the work, however, from west to 

 east has now, I think, conclusively demonstrated that the Has- 

 tings group, together with the somewhat more crystalline lime- 

 stone and gneiss groups above referred to, form one great 

 conformable series, and that this series rests quite unconformably 

 on a massive granitoid gneiss — the gneiss la of Sir William 

 Logan's Grenville map, published in 1865, in the Atlas to the 

 Geology of Canada. I wish it to be understood that I have not 

 personally examined this region, and I am therefore expressing 

 the views of Mr. Vennor, from which, however, I have no reason 

 to dissent. 



Of the actual distribution of this lower or " Ottawa" gneiss 

 very little is at present known with certainty, though it probably 

 occupies very extensive areas from the eastern shores of Lake 

 Winnipeg to Labrador. And between these same localities there 

 will doubtless yet be found many large areas of the so-called 

 Norian System. The first suggestion of this unconformable Upper 

 Laurentian series, which, it seems to me, is intimately connected 

 with the Hastings and Grenville series, appears to occur in the 

 supplementary chapters to The Geology of Canada, 1863, pages 

 838-839 ; but the evidence there given by no means proves the 

 subsequent assumption of this unconformity ; while the careful 

 descriptions by Sir W. Logan, both in the supplementary chapter 

 above cited and likewise in chapter III, shewing the intimate 

 association and interstratification of the orthoclase gneisses, quart- 

 zites and crystalline limestones with these supposed unconformable 

 Upper Laurentian anorthosites, much more strongly favor the 

 supposition that they are part and parcel of the great crystalline 

 limestone series. 



The exhaustive History of the labradorite rocks by Dr. Hunt, 

 in the volume already cited,* while giving much valuable and 

 interesting historical information, does not advance us a single 

 step beyond the position taken by Sir W. E. Logan, in 1863, as 

 regards their true stratigraphical relations. In not one of the 



* 2nd O. S. of Penn,, Special Report on Azoic Rocks and Trap Dykes. 



