QUARTZITE TONGUE AT REPUBLIC, MICH. 689 



idea that the jasper wedge is an interbedded member of the 

 upper series are these: (1) It is not interbedded. (2) The main 

 body of Upper Marquette quartzite to the west is as clearly 

 separated from the jasper wedge by an erosion interval as the 

 quartzite tongue is from the main body of Lower Marquette jasper 

 upon which- it rests. The jasper wedge cannot belong to the 

 upper series unless there are two upper series. (3) The jasper 

 of the wedge is not a fragmental rock, and no contemporaneous 

 fragmental material has been recognized in it. It disappears a 



Fig. 4. — Plan showing quartzite filling a crack in the Jasper Wedge. The black 

 bands are specular hematite ; the uncolored are red Jasper. The locality is ten 

 feet south of the suspended ladder. About one-sixth natural scale. 



short distance south of No. 8 tunnel, and the two quartzites come 

 together. If it were a member of the upper series, it must have 

 been laid down at the same time that a rather coarse fragmental 

 rock was being deposited a few hundred yards away, in which 

 case it is hardly conceivable that clastic material should not have 

 been largely included in it. 



V. 



While the relations of the quartzite tongue are correctly rep- 

 resented on Brooks' map, the better surface exposures of the 

 present day, and the large amount of exploration done by the 

 Republic Company, enable its position now to be fixed with much 

 greater precision. Several diamond-drill holes north of the 

 Thompson pit have shown that it extends 500 to 600 feet north 



