PRE- CA MBRIA N NOR TH A M ERIC A N LI TERA TV RE 755 



The Great Non -Conformity. 



The following general conclusions are reached as to the Lake Super- 

 ior region and other parts of the United States : 



The rocks of the Cortland series (the elastics), of the original 

 Taconic area, and of the upper series of the Adirondacks are of the 

 same age, /. e., Taconic or Lower Cambrian. 



The basic rocks of the Norian or Upper Laurentian system of 

 Canada are of the same age as the gabbros of the Adirondacks. 



The Taconic in America embraces all the strata containing any 

 known fossils older than those in the Dicellocephalus or Upper Cam- 

 brian. It is separated from the Archean by a profound unconformity. 



The Animikie strata in Minnesota and in general the upper iron- 



