690 A\-. J. MILLER PRE-CAMBRIAX FOLDIXG IX XORTH AMERICA 



not only to those of the Geneva- Snclbury area, but also nearly at right 

 angles to Euedemann's lines. 



Collins^ says that the generally assumed northeast structural trend of 

 Quebec and Ontario is, after alL not so persistent, and that probably, as 

 work proceeds, "many important irregularities like that in the Onaping 

 area will be discovered in the reoional trend.'' A sflance at the accom- 

 panying map plainly bears out this suggestion. 



In northern Ontario both the Amisk Lake area (Bruce, 1918) and the 

 Matachewan area (Cooke, 1919) show a north 60 to TO degrees east strike 

 of folds. 



The Rainy Lake district (Lawson, 1913) of southwestern Ontario 

 shows ordinary folding of two great sets of pre- Cambrian rocks with a 

 general north-northeast strike. 



In the Lake of the Woods region (Parsons, 1913) the general strike of 

 older pre-Cambrian rocks is north 60 to SO degrees east. 



Manitoba. — The Eeed-AVekusko area (Alcock, 1920) of northern Mani- 

 toba shows a north 35 degrees east strike; also, in northern Manitoba, the 

 Ospwagan Lake and the Southern Indian Lake areas. (Alcock, 1920) show 

 a general northeast strike. All three of these strikes cut across Euede- 

 mann's lines at high angles. The Knee Lake district (Bruce, 1920) of 

 central Manitoba mostly shows steep dips and strikes ranging from east- 

 west to southeast. 



WESTERX CAXADA 



Yery few observations on the structure of the pre-Cambrian rocks of 

 western Canada seem to be recorded, and these show little or no real 

 harmony with Euedemann's lines. In the Athabasca Lake region (Cam- 

 sell and Malcolm, 1919) the older pre-Cambrian rocks have high dips 

 with northeast strike at the lake and a strike varvinor from north-south 

 to northwest on Taltson Eiver. The younger pre-Cambrian rocks are 

 little disturbed. Between Athabasca Lake and Great Slave Lake (Cam- 

 sell, 1916) pre-Cambrian rocks range in strike from northwest through 

 north-south to northeast, with an average north-south trend. 



In the Selkirk Mountains and Interior Plateau (Daly, 1913) of 

 southern British Columbia a widespread earlier pre-Cambrian (Shuswap) 

 series is remarkably little deformed, and its strike is north TO degrees 

 east, or almost at rio^ht ano^les not onlv to the trend of the Eockv Moun- 

 tains, but also to Euedemann's lines. 



In the southernmost Eockies of Canada (MacKenzie, 1922) a remark- 

 able fact is that earlier pre-Cambrian rocks remained practically imde- 



9 W. H. Collins : Geol. Sur. Can., Mem. 95, 1917. 



