PRE-CAMBRIAN CLASSIFICATION IN ONTARIO 589 



et at. Owing to the confusion that has arisen in connection with 

 the use of the term the authors think it well to discard it. 



Among those, including Coleman, Collins, and the authors, 

 who have studied during recent years the pre-Cambrian rocks of 

 the Lake Huron-Lake Timiskaming region, there is agreement as 

 to most of the age relations, as will be seen from the classifications 

 on a following page, but different nomenclatures are employed. 



As to facts, the chief difference in opinion between Coleman 

 and the authors is in regard to the relations among what he calls 

 the Lower and Upper Huronian and the Animikie, and what we 

 call collectively the Animikean. It is agreed that the Cobalt series, 

 the Ramsay Lake series of Sudbury, and the usually fiat-lying 

 sediments of the classic area of Lake Huron are of the same age. 

 But in Coleman's opinion, as shown in his table, the sediments of 

 the Sudbury basin, the so-called Animikie series, are younger than 

 the Ramsay Lake series, which he classes as Lower Huronian. 

 But no discordance has been proved to exist between the Ramsay 

 Lake series and the Animikie of the near-by Sudbury basin. For 

 this and other reasons the authors class the Ramsay Lake series 

 and the Animikie together as the Animikean. In this they are 

 supported by investigations made by Van Hise and Seaman, who 

 say: "About half a mile east of Sudbury they found a breccia or 

 conglomerate [Ramsay Lake series] similar in every way to that 

 seen at Onaping [Animikie series of Sudbury basin] resting on the 

 eroded edges of Huronian [Timiskamian] and containing fragments 

 of it."^ 



Beginning with the bottom of the columns of the two classi- 

 fications, it will be seen that Coleman has accepted, provisionally 

 at least, our interpretation of the relations of the Keewatin and 

 the Grenville, described in a recent report.^ 



As is shown by Table II, Coleman and Collins use the name 

 Sudbury series or Sudburian for the rocks which we call Timis- 

 kamian. But Timiskamian has priority as it was employed by 

 the Ontario Bureau of Mines for rocks that occur at various points 

 over an area at least 5,000 square miles in extent before the term 

 "Sudburian" was introduced.^ Moreover, since Logan first 



^ U.S. Geol. Survey Bull. 360, p. 425. ^ q^^_ ^^^r. Mines, XXII, Part II. 



3 Eng. and Min. Jour., September 30, 191 1, p. 648. 



