X CONTENTS. 



Chapter IV. — The Upper Marquette series — Continued. Page. 

 Section II. — Tbe Michigammo Ibrmation, by C. R. Van Hise — Continued. 



Interesting localities 4.52 



Spurr, Michigamme. and Champion area 452 



Eastern area 454 



Lake Jlichigamme area 456 



Section III.— The Clarksburg formation, by W. S Bayley 460 



Distribution, exposures, and topography 460 



Rcl.it ions to adjacent formations i61 



Thickness and folding 463 



Petrographical character 463 



The massive greenstones 464 



The lavas 467 



Tbe sediments and tuff's 468 



Tbe sediments 468 



Gradation varieties between sediments and tuff's 472 



The tuffs 473 



The hornblende-schists 475 



The breccias and conglomerates 476 



Conclusions 480 



Interesting localities 481 



Summary 484 



CiiArxER V. — The igneoue rocks, by W. .S. Bayley 487 



Section I. — The pre-Clarksburg greenstones 488 



The bosses 489 



The eastern knobs 489 



Relations to Marquette sediments 489 



Petrographical character 490 



The western knobs 499 



Relations to Marquette sediments 499 



Petrographical character 500 



The dikes 506 



Petrographical character 508 



Ciratact effects 513 



The sheets and tuft's 514 



Tbe sheets 515 



The tuffs 517 



Section II. — The post-Clarksburg greenstones 518 



Petrographical character 518 



Quartz-diabases 519 



Oli vine-diabases 520 



Porphyrites 521 



Basalts - 522 



Summary 522 



Chapter VI. — The Republic Trough, by Henry Lloyd Smyth 525 



Introduction 525 



Section I.— The Archean 526 



