INTERESTma LOCALITIES OF THE ISHPEMIMi FOKMATIOX. 431 



21, p. 335). The greater portion of the ore taken from the Gcxxh-ich mine 

 is the recoinposed material of the Goodrieh quartzite. In all respects tins is 

 like that at the Volunteer mine, except that the detritus ming-led with the 

 ore is coarser, and therefore the replacenijent of tlie siliceous ingredients 

 by the iron oxide is very incomplete. The ore presents the appearance 

 of extreme mashing, being composed of thin plates and fibers of micaceous 

 hematite, the thinnest of which have slickensided faces, showing that there 

 has been shearing between them. The conglomerate above shows tlu; 

 same dynamic effects, the lamin?e of micaceous hematite wrapping around 

 the more resistant quartz and jasper pebbles. As usual, in places between 

 the lamiufE of sheared hematite and in cracks a great deal of magnetite in 

 crystals has been formed. The exposures of the basal conglomerate at 

 the Saginaw, Goodrich, and Lowthian mines are scarcely less beautiful 

 than those in sec. 16 (see p. 425) and at Palmer. The conglomerate, 

 composed mainly of the Negauuee formation material, contains pebbles 

 of white, coarsely crystalline quartz, and is in places at least 300 feet 

 thick. It grades gradually upward into a fine-grained conglomerate, in 

 which the ore and jasper are still prominent, but in Avhich coarse-grained 

 quartz is abundant This passes up into the coarse-grained quartzite, in 

 which there is comparatively little of the chert and jasper, and this into 

 ordinary quartzite, which in the higher horizons is interstratified with 

 graywacke. 



At the east end of the ridge, about one-fourth mile north of the center 

 of sec. 21, the conglomerate is infolded with the Negaunee formation in an 

 isoclinal manner, the Goodi-ich rock making a westward-plunging tongue. 

 A section from soutli to north passes from the Negaunee formation to the 

 Goodrich and then to the Negaunee, the dip being continuously at a high 

 angle to the north. At this locality the Goodrich conglomerate is very 

 much mashed. The pebbles of jasper are flattened, and iu the plane 

 of flattening are elongated unequally in two directions at right angles to 

 each other. The finer detritus shows slickensiding efiects. Some of the 

 finer-grained varieties of the rock are gra}', siliceous or ferruginous slates 

 or schists, the more feiTUginous approaching in appearance the so-called 

 slate ore. 



