444 THE MAEQUETTE IKOiS" liEAltlNG DISTKIGT. 



At the Magnetic mine, and east and west of it, a coarse-grained gray 

 quartzite is associated with the ordinary phases of quartzites. In this quartz- 

 ite, liornblende and epidote occur as chief constituents between the grains. 

 These rocks are in all respects like those which have been described in the 

 quartzite tongue at Republic. In some of the micaceous schists of the same 

 area a large amount of garnet, chlorite, and chloritoid is present. 



By the replacement of mica by griinerite and green hornblende in the 

 mica-schists these rocks grade into the griineritic rocks which have been 

 described under the name Bijiki schist. The transition varieties and the 

 griineritic rocks which are free from mica are not different from those which 

 occur northwest of Champion (pp. 434, 436). As usual, garnet is abundant. 



SECTIOX II.— THE michiga:m]Me for>iatiox. 



By C. R. Van Hise. 



The name Michigamme is given to the upper slate and mica-schist 

 because on the islands of Lake Michigamme and on the mainland adjacent 

 to the shore occur extensive exposures of this formation. 



DISTRIBUTION, EXPOSURES, AND TOPOGRAPHY. 



The jMichigamme forTuation is mainly in a single great area (Atlas 

 Sheet IV). Beginning west of Ishpeming, it sweeps westward as a broad 

 belt to near Humboldt; here it becomes somewhat contracted, and east of 

 Lake Michigamme it is divided into two belts, a narrow northern belt 

 between two zones of Bijiki schist, and a broader southern belt which 

 includes the greater part of Michigamme Lake and the country to the 

 westward. This belt widens out over a broad area and occupies a g'reat 

 expanse of countr}' in the large area of Algonkian rocks at the west and 

 south part of the district covered l)y the present report. From this broad 

 area two arms ])roject, forming the centers of the Republic and Western 

 tongues. At and east and west of Humboldt is a southern lenticular area 

 about 6 miles long. 



As this formation was originally a shale or grit, where it has not been 

 much altered the exposures are not prominent, and the area as a whole is 

 one of rather feeble relief, occupying lowlands between the ridgv countrv 



