IRON AND OTHER ORES OF ONTARIO. 187 



exception of two localities, where bog iron occurs, which is not a 

 deposit in the same sense. In a paper on the economic minerals of 

 Canada, which Mr. W. Hamilton Merritt, M.E., F.G.S., read before 

 the British Association at their Montreal meeting in 1884, he 

 enumer-ated the localities in which the various ores occurred, and 

 the Geological formations in which they were found. In reference 

 to the iron of Ontario, he stated that in the Lake Superior District 

 it oocurred in one instance in the Devonian, and that in the Lake 

 Ontario and St. Lawrence District it occurred in four cases in the 

 Silurian. These particulars he subsequently stated he had obtained 

 from a mineral map of the Dominion displayed at the Paris Exhi- 

 bition of 1878. That map is not published and in the absence of 

 it I find no evidence of the existence of Devonian strata on the 

 Canadian side of Lake Superior, and the apparent occurrence of iron 

 in the Silurian rocks of the eastern part of the province may perhaps 

 be explained away. I think it will be found that the iron deposits 

 proper are all pre-Silurian. 



The Geology of my map is based on the very small map published 

 by Sir William Logan in 1866, to illustrate the Geology of Canada, 

 and revised by the present director. Dr. Selwyn for the Dominion 

 Atlas in 1876. 



According to that map it appears that the mines at Blairton and 

 Seymour, and also that at Gios Cajj on Lake Superior occui^in, or 

 are overlaid by Silurian strata. Unless, indeed, and it is a perfectly 

 legitimate alternative, there be at the points where those mines occur 

 inliers of the Archean rocks. This is, of course, a matter of obser- 

 vation in the field. In the case of Blairton and Seymour it is the 

 more probable as those localities appear by the map to lie within the 

 valley of the River Trent, whilst the Gros Cap Mine occurs so near 

 the outcrop of the Archean rocks that it is probable the ore is ob- 

 tained therefrom.* 



How meagre do these references seem when one thinks of the 

 beautiful and voluminous census returns and monographs devoted 

 to the Geology of the same formations on the opposite slioros of our 

 own lakes ! Or, without soaring to the Monographs of the United 



* Although engaged during the whole of the summer months in exploring geologically the 

 Huronian and Laurentian regions lying between those extremes the author did not visit 

 either Blairton or Gros Cap and cannot therefore speak from personal observation, but is sat- 

 isfied frofti analog}' that his conclusion is correct. 



