ANALYTICAL ABSTRACTS. 535 



other dykes containing crystals of feldspar, while both are cut by gray 

 granite, that is in turn cut by red granite. 



The Republic formation, commencing with the oldest division, is divided 

 roughly as follows : Conglomerate-breccia and conglomerate-schist ; quart- 

 zite ; dolomite ; jaspilite and iron ore ; argillite and schist ; granite and 

 felsite ; diabase ; diorite and porodite ; porphyrite. At the base of the 

 Republic formation is a series of conglomerates and conglomerate-schists, 

 which pass into hydrous mica-schists. Near Palmer, the coarse conglomerate 

 rests on the gneiss to the south, and is overlaid to the north by quartzite, 

 fragmental jaspilite and quartz-schist. The dip is about 4.0 northward. 

 The conglomerate contains numerous pebbles of gneiss, as well as some of 

 granite, diorite, schist and quartz veins. Near the Volunteer mine quartzite 

 immediately overlies the basal conglomerate, and in other places reposes 

 directly on the Cascade formation. 



The quartzite in the Menominee district, running from Sturgeon river 

 along Pine river to Metropolitan, is thought to belong to the base of the 

 Republic formation, since it is found at various places close to the gneiss and 

 granite, dipping away from them, and is cut by dykes of granite in Sec. 12, 

 T. 41 N., R. 30 W. The dolomite occupies a low horizon, either interbedded 

 with the quartzite or occupying its place. The fundamental ore and jaspilite 

 appears to belong, stratigraphically, to the Republic formation. The most of 

 the jaspilite of the formation is of detrital origin, being originally conglomer- 

 ates, breccias, sands, muds, which have been subsequently chemically acted 

 upon by percolating waters, since in the Cascade range the jaspilite and ore 

 form layers which are frequently interlaminated with quartzite. The jaspilite 

 of Negaunee and Ishpeming has failed to reveal any evidence that it is 

 sedimentary, although the associated argillite and schist are in part at least 

 clearly sedimentary. The argillite and schists are directly associated with 

 the jaspilite and iron ore. In places they grade up into the fragmental 

 jaspilite, and in other places are interbedded with it. They also succeed 

 the latter rocks and overlie them. These argillites and schists are older 

 than the diorites of the district, and are cut by them. 



The Holyoke formation has the following succession, as far as known, 

 commencing with the base : Conglomerate breccia and conglomerate schist ; 

 quartzite ; dolomite ; argillite ; graywacke and schist ; granite and felsite ; 

 diabase, diorite and porodite ; peridotite, serpentine and dolomite ; melaphyr 

 or picrite ; diabase and melaphyr. The conglomerate at the base of the 

 Holyoke contains granitic material, as well as fragments from the jaspilite. 

 In many places the unconformity between the Republic and Holyoke forma- 

 tions is most marked, being seen at many of the mines. In many places, also, 

 the Holyoke formation overlaps the Republic, and is in contact with the 

 granite and gneiss of the Cascade. Associated with the Holyoke conglom- 



