362 Scientific Proceedings, Royal Dublin Society. 



locality of the Irish metamorphosed Cambrians or Cambro-Si- 

 lurians.' 



To return to the boundaries of the Ontario Laurentians and 

 Huronians : it would appear to me that they are more lithologieal 

 than stratigraphical, as in no place does there seem to be a regular 

 unconformability or even an overlap of the Huronians on the 

 Laurentians, while on both sides of the boundaries there are strik- 

 ing similarities in the directions and dips of the beds in each class 

 of rocks, while all the cracks and faults in the supposed older rocks 

 occur also in the supposed newer. 



If it be allowable to compare small things with great, a paral- 

 lel may be drawn between the section of the metamorphosed Cam- 

 brians of the Forlorn Promontory, county Wexford, and that at the 

 rapids out of the Lake of the Woods, one being a pocket-edition 

 of the other. At the Forlorn section, going southward, we first 

 meet typical schists, which are succeeded by gneiss, there being 

 a hard boundary between the two ; the gneiss, however, to the 

 southward begins to alternate with beds of schist, and before the 

 Point is reached all the rocks are schists. In the Canadian section, 

 going northward, you first cross schists, then you come to a hard 

 boundary, north of which is gneiss ; but still further northward in 

 the gneiss there are subordinate schists, which seem in one place to 

 be of considerable thickness, as the water has cut out a very consi- 

 derable bay apparently into rocks of a more frail character than 

 the gneiss. 



I am aware that Sterry Hunt and others have suggested that 

 these older rocks were accumulated under very different circum- 

 stances from the younger ones ; tliey being in a great measure 

 more chemical than sedimentary accumulations. Such a supposi- 

 tion, however, appears to me, now that I have seen the Canadian 

 rocks, to be unnecessary, if not untenable, as these supposed chemi- 

 cal accumulations are in a great measure similar to much younger 

 rocks in the Old Country, where their characters, as can be proved 

 by ocular demonstration, are not due to chemical accumulation, but 

 to metamorphic action long subsequent to their first accumulation. 



^ Years ago I examined the collection of Canadian Archsean rocks, sent over by 

 Sir "W. Logan to the Eoyal School of Miaes, London, to illustrate hisEeport, and in them 



I only found a few rocks that did not occur in the Cambrians and Cambro- Silurians of 

 West Galway. _ ^ 



