BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 32, pp. 267-292 JUNE 30, 1921 



PRE-CAMBEIAIS^ ROCKS OF MANITOBA ^ 



BY F. J. ALCOCK AND E. L. BRUCE 



{Read before the Society December 28, 1920) 



CONTENTS 



Page 



Introduction 267 



General character of the country 268 



General character of the pre-Cambrian rocks 270 



Tabulated summary 270 



Description of areas 270 



Athapapuskow Lake area 270 



Reed-Wekusko area 273 



Cross-Pipestone area 275 



Knee-Oxford Lakes district 277 



Gods-Island I^akes area 281 



Burntwood River area 282 



Rice Lake-Wanipigow River area 283 



Star Lake area 283 



Churchill River areas 284 



Narrow Lake area 284 



Lake of the Woods and Rainy Lake areas 285 



Comparison of the areas , 287 



Origin of the pre-granite complex 288 



Distribution 288 



Lithology 289 



Succession 289 



Thickness 289 



Bedding 289 



Cross-bedding 290 



Conclusion 290 



Summary of geological history 291 



References 292 



Introduction 



The consolidated rocks of three-quarters of the Province of Manitoba 

 are of pre-Camhrian age. Our geological knowledge of these rocks has 



^ Manuscript received by tlie Secretary of the Society March 10, 1921. 

 Read by E. L. Bruce. (267) 



