Chapter II. 

 PRE-CAMBRIAN. 



The pre-Cambrian of North America has been described in detail and with 

 exhaustive consideration of the Hterature in the revised correlation bulletin on the 

 pre-Cainbrian by Van Hise and Leith/^^ That work makes any description of the 

 terranes superfluous in this paper, which will confine itself to a list of the areas colored 

 as pre-Cambrian (see fig. 3) and an account of the efforts made to reach a satisfactory 

 classification for the purposes of the geologic map of North America. 



Pre-Oamirian areas. 

 Keewatin (33a). o 



L-M 15-16 Minnesota, Wisconsin, Michigan, Ontario. 



"Laurentian" (23). 



L I^r-IG Wisconsin, Michigan, Minnesota, and North Dakota (undifferentiated pre-Cambrian,. 



which is mapped with "Laurentian"). 



L 19-20 New Brunswick, Nova Scotia. 



L-M 21-22 Newfoundland. 



L 17-18, M 14-21, N 13-21,|g^^^^j^jj shield: Ontario, Quebec, Manitoba, Saskatchewan, Alberta, Northwest Terri- 



„ ~ ' ' " 'I tories. 

 R 8-19 J , 



S 14-18, T 17-19, U 17-18 Arctic Archipelago. 



P 22-23, Q 22, R 22, S 21,i„, ^ , ,„ , , 

 ' ^ , , , i-^gaj- gQast of Greenland. 



T 19-20 / 



P 23-24, Q 25, R-S 26-27,.^^^^^^^^^^^^^^^^^^^ 



• T 27 J 



laurentian (23(1). 



L-M 15-16 Minnesota, Wisconsin, Michigan. 



Earlier (?) pre-Cambrian unclassified (22). 



L 12 Montana (Cherry Creek group, early Algonkian; mapped with Belt series, 21a, late 



Algonkian). 



Lr-N 17-18 Ontario, Quebec. 



M-N 15-16 Ontario, Northwest Territories. 



M 21 Newfoundland. 



JJ 13-14 Saskatchewan, Northwest Territories. 



N 19-20 Quebec, Northwest Territories. 



O 12 Saskatchewan. 



20 ■- Labrador. 



P 12-15, Q 11 Northwest Territories. 



X 19 Greenland. 



a Numbers in parentheses refer to numbers of corresponding color blocks on the map. 

 62 



