33 



and are so intimately infolded and so highly metamor- 

 phosed that their respective distribution in the Bancroft 

 area cannot now be determined. 



VIII. — Relation of the Grenville Series to other 

 Pre-Cambrian Series. 



In the southern portion of the Laurentian highlands 

 to the west of the area occupied by the Grenville series, 

 that is, north of Lake Huron and in the district about 

 Lake Superior, Rainy lake and Lake of the Woods, other 

 Pre-Cambrian series, differing essentially in petrographical 

 character from the Grenville series, are found. These are, 

 enumerated in ascending order, the Keewatin, Huronian, 

 and Keweenawan series. Up to the present time the 

 Grenville series has nowhere been found in contact with 

 these; but it is hoped that the relation of these eastern 

 and western Pre-Cambrian developments may eventually 

 be determined, in order that a correlation may be made 

 between them. Until this has been done, however, their 

 relations must remain a matter of mere conjecture. The 

 two successions, then, are as follows: — 



Western District. 



Eastern District. 



Upper Cambrian— Potsdam sandstone 



— Unconformity— 



Upper Cambrian — Pots- 

 dam sandstone. 



- Unconformity- 





Keweenawan. 





• 





- Unconformity- 







Pre-Cambrian ■ 



Huronian ■ 



Upper (Ani- 



mikie). 

 -Unconformity ■ 

 Middle. 

 - Unconformity 

 .Lower. 



Pre-Cambrian • 



Grenville 

 series. 

 Intrusive 

 contact. 





- Unconformity- 

 Keewatin. 



Intrusive contact. 







Laurentian. 







Laurentian. 





35064—3 



