CONTENTS. 9 



Chapter IV. — The Lower Hueonian — Continued. Page. 

 Section I. Sedimentary rocks — Continued. 

 Knife Lake area — Continued. 

 Relations — Continued. 



Relations of Lower Huronian sediments to adjacent formations — Continued. 



Relations to the Keweenawan 307 



Relations to the Keweenawan gabbro 307 



Relations to basic dikes 307 



Age 308 



Ogishke conglomerate 309 



Petrographic characters 309 



Macroscopic characters 309 



Microscopic characters 312 



Metamorphism 313 



Thickness 317 



Interesting localities 317 



Agawa formation (iron bearing) 324 



Distribution and exposures 324 



Distribution 325 



Exposures 326 



Structure 326 



Petrographic characters 327 



Origin 329 



Relations to other formations 329 



Age 330 



Thickness 330 



Interesting localities 330 



Knife Lake slates 335 



Petrographic characters 336 



Macroscopic character 336 



Microscopic character 337 



Metamorphism 340 



Contact effect of the granite 340 



Contact effect of the gabbro 342 



Petrographic characters of the metamorphosed slates 344 



Microscopic characters 344 



Thickness 346 



Interesting localities 347 



Structure and relations of the slates 347 



Contact metamorphism of the slates 349 



Section II. Acid and basic intrusives 352 



Introduction , 352 



Giants Range granite 353 



Distribution, exposures, and topography 353 



Distribution ___ 353 



Exposures 354 



Topography 354 



Petrographic characters 354 



Macroscopic characters 354 



Relations to adjacent formations 356 



Relations to Ely greenstone 356 



Relations to Soudan formation 356 



Relations to the Lower Huronian sediments 356 



Relations to the gabbro 357 



Age 358 



