448 THE PENOKIIE IRON-BEARING SERIES. 



At the west braiioli of the Montreal, T. 4G N., R. 2 E., Wisconsin, 

 green schists are again found in contact with the rocks of the quai-tz-slates. 

 The contact^ here exposed is of much smaller size than at Potato river and 

 to that extent is less satisfactory, but even here all the essential facts are 

 the same. A l)asal conglomerate is found, the fragments of which are very 

 largely from the green schist; this conglomerate quickly varies into the 

 nornoal slate of the regioi , as at Potato river; the fibers of the green schist 

 abut against the conglomeratic slates. 



Just south of the Aurora mine the Quartz-slate is exposed in direct con- 

 tact wnth the granite. The basal horizon is here a cherty slate which does 

 not take on a conglomeratic aspect. The granite surface is plainly one 

 of erosion and into its pre-Penokee joints and cracks the detritus of the 

 Quartz-slate has sifted. 



A short distance north and west of the east quarter post of Sec. 15, T. 

 47 N., R. 46 W., Michigan, on the railroad spur of the Palms mine is another 

 contact between the Southern Complex and the Penokee rocks. Here the 

 jniK'tiou is between granite and a conglomerate belonging to the Quartz- 

 slate mend^er. A ledge of massive granite is faced by a conglomerate, 

 which penetrates the clefts and hollows of the granite. In the granite 

 fresh microcline and chlorite are abundantly contained. Tlie fragments 

 of the conglomerate are mainly granite, l:)ut chert, jasper and quartz 

 are also found. These fragments are in part well rounded, but mostly 

 are anffulai-, as is connnon when near their source. Mucli of the feldsi)ar 

 of the fragments is beautiful, fresh microcline. Green chlorite in well 

 defined masses is also plentiful. It is certain that this debris was derived 

 from the granite. The coarse grained granite at this place plainh^ consti- 

 tuted the surface rock wlien the conglomerate was formed and contributed 

 material to it. Noi'th and east of the conglomerate, after a short covered 

 space, an' found the ordinarv i)hases of slates of the Quartz-slate member, 

 dipping north at their normal angle. The time gap here between the 

 conglomerate and granite must be taken to be great if it is conceded that 

 the presence of normal granite at the surface is proof that it is an old rock. 



About 700 steps soutli and 7") steps east of the northwest corner of 

 'This contact was first dcsiribeil liy Dr. T, C. Chamberlin. See Literature, pp. 43, 44. 



