302 



THE PENOKEE IRON-BEAEING SERIES. 



due to the fact that the rock in large measure becomes a somewliat resistant 

 mica-schist, wliich is interstratified with quartzites and massive gray wackes. 

 East of this locahty the exposures are not numerous until Tylers fork is 

 reached. Here, while they are large, they are in a good measure due to the 

 cuttinsr action of the river. No bluffs and hills of slate are found, as west 

 of Bad river. Numerous large exposures are in the south part of Sec. 12, 

 T. 45 N., R. 1 E., Wisconsin, just south of a small lake. The slates and 

 graywackes here are the north slope of a steep bluff which rises rapidly 

 from the water of the lake. The only remaining large exposures in the belt 

 are those along the railroads in the west part of Sec. 28, T. 46 N., R. 2 E., 

 Wisconsin. The slates and graywackes are here a prominent landmai-k, 

 rising in a bluff of some size in the valley between the iron and trap 



ranges. 



General petrugraphical character. — It has already been said that the 

 rocks of the member under consideration are distinctly clastic, or at least 

 are rocks which can be shown to have been once fragmental. While they 

 are alike in this fundamental point there is great variety in minor charac- 

 teristics. The varieties may be grouped under the heads: (1) Mica-schists 

 and mica-slates; (2) Graywackes and graywache-slates ; (3) Clay-slates or 

 pliyllites; (4) Quartzites and conglomerates. Each of these main types has 

 the various phases shown by the following tabulation: 



Mica-schLst and mica-slate. 



Micaceous 



(^Micaceous a 



rMn 

 i Biu 



11(1 ihloritic 



Graywacke and graywacke-elatu. 



Clay-slate or phyllite 



Quartzite aud conglomerate 



Micaceous. 



Mnscovitic. 

 ^ iiiotitic. 



l^Muscovitii' anil biotitic. 

 ^ Chli>ritif anil liiotitic 

 i Chloritie and sericitic or muscovitic. 



^ Biotitic. 



) Biotitic and muscovitic. 

 Micaceouii and chloritie Cbloritic and biotitic. 



r Chloritie. 

 Chloritie I Maguetitie and chloritie. 



[Ferruginous and chloritie. 



\ Chloritie. 



) Chloritie and raagnetitic. 



^ Clayey. 



) Feldsiiathic. 



