INTERESTING LOCALITIES OF THE WEWE SLATE. 281 



however, shows the completely crystalline cliaracter of the one and the 

 reconiposed character ctt" the other. 



Northwest of this cong-lonierate bluff", making- anotlier considerable set 

 of bluffs in the northwest part of sec. 22 and the northeast part of sec. 21, 

 are the typical cherty and brecciated We we slates and graywackes. Con- 

 sequent upon the northwest plunge of the fold, the higher members are 

 found on the southwest, northwest, and northeast sides of the exposures, 

 the coai'sely conglomeratic phases being limited to the southeastern hills, 

 though distinctly conglomeratic phases occur at higher horizons. The 

 slates, gravwackes, and novaculites, their cleavage and foliation, their brec- 

 ciation, silicification, and ferruginatiou (figs. 12 and 13, and PI. IX) are \ery 

 similar to those phenomena described in the ledges east of Goose Lake, 

 in sees. 13 and 24. Parallel to the bedding are either cherty or novacu- 

 litic layers, which are traversed by veins of quartz. The usual strike is 

 N. 15° W. to N. 40° W., and the dip at an angle of 50° to 60° north of east. 

 The bedding is usually cut by a foliation, which strikes about N. 50° W. 

 and has a vertical dip. The breccias are more extensively developed in 

 the locality under consideration than anywhere else. Many of the ledges 

 are traversed in all directions by veins of white quartz, but the majority 

 of these are parallel to the schistosity. Near the northwest part of the 

 exposures, on one of the more prominent bluffs, the extreme stage of 

 dynamic action is represented by a remarkable reibungsbreccia. The 

 fragments are all of the black slaty or cherty rock. They vary in size 

 from minute ones to great blocks several feet in diameter. The whole 

 is recemented mainly by vein quartz, but in part by hematite and jasi)ery 

 quartz. The veins of the latter are later than the white quartz veins, and 

 where of some width the bands of ore or jasper could not be discriminated 

 from the feiTuginous jasper of the Negaunee formation. This breccia 

 differs from a true conglomerate in that the cementing material is of a vein 

 character, the fragments all of one kind, and usually exceedingly angular. 

 The black and gray schist, set in the quartz veins and ornamented by the 

 specular hematite and red jasj^er in smaller quantity, makes the exposure a 

 beautiful one. The fragments of schistose slate often have around them 

 parallel zones of quartz, hematite, and jasper, although usually the quartz is 



