BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 12, pp. 343-376. PLS 29-32 AUGUST 31, 1901 



KEEWATIN AREA OF EASTERN AND CENTRAL MINNESOTA 



BY C. W. HALL 



{Presented before the Society December 30, 1899, and December 28, 1900') 



CONTENTS 



Page 



Introduction 344 



Geographic subdivisions ■ 344 



Rock relations along the border 345 



Keewatin of the Saint Louis River district .' 346 



Rocks of the series and their relations 346 



External characters 347 



Structural features 348 



Structure and distribution of the concretions 349 



Quartz veins 349 



Diabase dikes 349 



Joints and fractures 349 



The Blackhoof valley 350 



Moose River valley 351 



Mahtowa exposures 351 



Barnum exposures 351 



Moose Lake exposures 352 



Kettle River section 352 



Region west of Sturgeon lake 353 



Snake River localities 355 



Rum River valley 356 



Morrison county 356 



Granite areas 357 



Lithology of the series 357 



The problem presented 357 



Other localities cited 357 



Historical notes 358 



The gray wackes 359 



The gray wacke slates 361 



The clay slates 362 



The hornblende gray wackes 362 



The hornblende schists 363 



The hornblende-biotite schists '. . 365 



The biotite schists 365 



The staurolitic biotite schists 365 



The limestones 366 



XLIX— Bull. Geol. Soc. Am., Vol. 12, 1900 (343) 



