VOLUME XXIII NUMBER 7 



THE 



JOURNAL OF GEOLOGY 



OCTOBER-NOVEMBER 19 15 



REVISION OF PRE-CAMBRIAN CLASSIFICATION 

 IN ONTARIO^ 



WILLET G. MILLER and CYRIL W. KNIGHT 

 Ontario Geological Survey, Toronto, Canada 



The pre-Cambrian rocks of Ontario have undergone much 

 scrutiny during the last seventy years. At the very beginning 

 of his labors as provincial geologist of Canada (Ontario and Quebec) 

 in 1843 Logan confirmed the observations made by other investi- 

 gators, that the oldest fossiliferous rocks lie unconformably on 

 a vast crystalline series. By degrees he and his associates, work- 

 ing in the regions adjacent to the Ottawa River and to the north 

 shore of Lake Huron respectively, came to the conclusion that 

 these ancient rocks as regards their age relations are divisible into 

 two great groups, the older of which was named the Laurentian 

 and the younger the Huronian.^ Other pre-Cambrian rocks were 

 studied on Lake Superior. ^ To these was given the name Upper 

 Copper-bearing Rocks of Lake Superior. They were divided 

 into two groups, the upper of which has come to be known as the 

 Keweenawan and the lower as the Animikie. 



' This paper was presented in abstract at the meeting of the Geological Society 

 of America, December, 1914. 



= American Association for the Advancement of Science, 1857; Geology of Canada, 

 1863, pp. 22 f. 



3 Geology of Canada, 1863, pp. 67 f. 

 Vol. XXIII, No. 7 585 



