456 THE MAEQUETTE IKON BEARING DISTRICT. 



T. 47 N., R. 27 W. These exposures mark a moderate ridge, which, how- 

 ever, is not continuous. Both macroscopically and microscopically these 

 rocks are in all respects like those north of Clarksburg, and they therefore 

 need no further description. 



Lake Michigamme area. — Returning uow to tlio Lake Michigamme area (Atlas 

 Sheecs V, VI, and VIII), at the east end of the lake mica-slates are found. 

 On the islands in the center of the lake and on the mainland adjacent 

 there are very numerous exposures of mica-schist. These appear to be 

 completely crystalline rocks. For the most part they have a moderately 

 strong foliation. In many places they are thickly studded with crystals of 

 garnet and staurolite. These are especially prominent upon the weathered 

 surface, as the background has dissolved and left these crystals projecting. 

 At most places the schistosity is the only strvicture observable, but in some 

 places alternating bands of coarse and fine material, cutting across the 

 schistosity, indicate the probable original bedding. It will be remembered 

 that adjacent to Champion the rocks of the Michigamme formation are but 

 little-altered shales and graywackes. At the east end of the lake tlie rocks 

 are intermediate in their crystallization, being mica-slates. We therefore 

 have a pi-ogressive increase in the metamorphism of the rocks from their 

 little-altered condition to completely crystalline schists, the change occur- 

 ring in a distance along the strike of about 4 miles. 



West of the islands, and probably a continuation of the same horizon, 

 running through sees. 32 and 33, T. 48 N., R. 30 W., is a ridge upon which 

 are very numerous exposures, in all respects like those of the islands and the 

 shore. The exposures also extend to the water's edge in sees. 28 and 29. 

 For the most part the ledges are of the same general character, but in some 

 places coarser layers are interstratified with finer ones. These apparent 

 beds are in a series of rolls which are cut across by the schistosity. In 

 the southwest part of sec. 29 in this area are the peculiar pegmatized 

 exposures of mica-schist, which, on account of their exceptional characters, 

 are fully described in the general characterization on pages 447-448, 450. 



Toward the western end of the lake, in sec. 30, T. 48 N., R. 30 W., 

 and in sees. 25 and 36, T. 48 N., R. 31 W., there are occasional exposures, 

 and here the rocks are somewhat less crystalHne, containing little or no 



