37 



PORT ARTHUR TO WINNIPEG VIA CANADIAN 

 NORTHERN RAILWAY. 



BY 



W. L. Uglow. 



INTRODUCTION. 



The excursion over the Canadian Northern railway from 

 Port Arthur to Winnipeg affords an opportunity of seeing 

 an unusually complete Pre-Cambrian section. Within 

 this distance of 230 miles (370 km.) every Pre-Cambrian 

 series that had been differentiated in the Lake Superior 

 region is exposed to a greater or less degree. In addition, 

 the base of the section is formed by the Coutchiching 

 series, one that is rare in other localities, and which is 

 claimed by those who have studied it specially, to be even 

 older than the Keewatin. The area also contains, in 

 exposures of fossiliferous Lower Huronian limestone, the 

 oldest known records of life. 



A few broad topographic features should be mentioned at 

 the outset. Two chief types of topography are well repre- 

 sented: the rocky lake country, and the alluvial plain. 

 Generally speaking, the former occupies the eastern part 

 of the region traversed, although the first 25 miles (40 km.) 

 of the trip are across the post-glacial flood-plain of 

 Kaministiquia river. West of Rainy lake, rock exposures 

 and hills are rarely seen, and the level country passed 

 through is in part the alluvial plain of Rainy river, and in 

 part the bed of glacial Lake Agassiz, (12) which continues 

 to Winnipeg. 



The most recent classification of Canadian Lake Superior 

 geology is that by Dr. Andrew C. Lawson in his new report 

 (6) on the Rainy Lake region. For purposes of reference 

 his table of formations is reproduced below, in full. What 

 are believed to be the equivalents of the various series in 

 the nomenclature of the International Committee and of 

 the United States Geological Survey are included in 

 parentheses. 



Algonkian fKeweenawan (Keweenawan). 



(No equivalent). \ Unconformity. 



[Animikie (Upper Huronian). 



