416 THE MARQUETTE IliON-BEAKIi^G DISTRICT. 



and the rocks l)ecome inica-gueisses. Various accessory minerals, such as 

 chlorite, epidote, and zoisite, are found in the quartz-schists, mica-schiats, 

 and mica-gneisses. 



At various localities there are exceptional varieties of rocks which 

 belong to the Goodrich quartzite, but these will not be considered here. 

 They are described later in connection with the localities at which they 

 occur. 



THICKNESS. 



The thickness of the Goodrich quartzite is variable, and no average 

 estimate can be given, as it is not sharply delimited above. The best- 

 known localitv to determine its thickness is north of the Saginaw mine, 

 where it has a surface width of about 1,800 feet and an average dip of 

 jDrobably not less than 60°. This would give a thickneso of about 1,550 

 feet. Since the transgression horizon here rapidly cuts across the iron for- 

 mation, which a short distance to the west Is reduced to a narrow belt, it is 

 probable that this thickness Is much beyond the average of the formation, 

 even for the Ishpeming area, and that it is several times as great as in the 

 western part of the district. 



THE BIJIKI SCHIST. 



The second division of the Ishpeming formation is the Bijiki schist. 

 The rock is given this name because typical exposures of it occur near the 

 mouth of Bijiki River. They were regarded by Brooks as anthophyllitic 

 schists. 



DISTRrBUTION, EXPOSURES, AND TOPOGRAPHY. 



This schist has three narrow belts. The northernmost one extends, 

 with frequent exposures, from the west end of the district, just south of the 

 Goodrich quartzite, to sec. 28, T. 48 N., R. 29 W. (Atlas Sheets V, VHI. and 

 XII). The belt may extend somewhat farther to the east than this, but 

 there are no exposures. The second belt is a short distance south of the 

 first. It runs along the northern side of Miehig-amme Lake to a point 

 northeast of Champion. The third belt extends from the southern extrem- 

 itv of Michlgamme Lake to Champion, and is north of the southern belt of 

 Goodrich quartzite. The Bijiki schist thus appears to be confined to the 

 west end of the district. In the time scale it must be equivalent to a part 



