ILLUSTRATIONS 



Plate 1. Colored map showing distribution of pre-Cambrian and other rocks in the Lake 

 Superior region, and the geographic relations of the Vermilion district of Minnesota 



to the other iron-bearing regions of Lake Superior 32 



II. General geologic map of the Vermilion district 34 



III. A and B, Spherulitic texture in the greenstones 142 



IV. A, Ellipsoidal parting in greenstone; B, Ellipsoidally parted greenstone, showing 



spherulitic development 146 



V. A, Amjrgdaloidal greenstone (metabasalt); B, Magnetitic chert, showing possible 



lines of false bedding 168 



VI. A, Folded jasper about one-half mile east of Jasper Peak; B, Contorted jasper and ore 

 in the NE. J sec. 25, T. 63 N., R. 12 W.; C, A breccia of jasper and chert fragments 



in greenstone matrix 176 



VII. Folded jasper and slate, showing slaty cleavage developed in slate bands 178 



VIII. Panoramic view of the ore basin north of Ely, showing shafts of the Chandler and the 



Pioneer mines 216 



IX. A, View of main level timbering, Minnesota mine; B, Filling system, Minnesota 



Iron Company, Minnesota, with chute for discharging refuse from upper levels 236 



X. A, View showing method of loading cars; B, View of main drift which has begun to 



cave, Chandler mine 238 



XI. Scrammers in mine using caving system 240 



XII. A, Photomicrograph, showing granules in Gunflint formation; B, Photomicrograph, 



showing details of granules 382 



XIII. A, View of sawtooth hills of Rove slate capped with dolerite sills, at the northeast 

 end of Rose Lake, international boundary; B, View on an island in Burntside Lake, 

 showing granite of Burntside Lake cutting amphibole-schists, metamorphosed Ely 



greenstone 392 



Fig. 1. Reproduction of sketch by A. Winchell showing the intricate relationship between the 



granite of Burntside Lake and the amphibole-schists 158 



2. Reproduction of sketch by A. Winchell showing the intricate relationship between the 



granite of Burntside Lake and the amphibole-schists 159 



3. Sketch showing Soudan formation infolded in Ely greenstone, both cut by Keweenawan 



dolerite dike 205 



4. Illustration showing distribution and relations of Ely greenstone, Soudan formation, 



and Ogishke conglomerate south of Moose Lake 206 



5. Sketch showing association and relations of Ely greenstone, Soudan formation, and 



Ogishke conglomerate 207 



6. Sketch showing relations between Soudan formation and Ely greenstone on Otter Track 



Lake 208 



7. Sketch made in the field, showing relations of Soudan formation and Ely greenstone on 



Jasper Lake 209 



8. " Vertical section across Chandler ore body along line E-F offig.9 216 



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