GENERAL GEOLOGY OF THE DISTRICT. 449 



Sec. 13, T. 47 N., R. 4() W., Micliigau — i. e., al)(>ut 2 miles east of the con- 

 glomerate just described — is a somewhat similar occurrence. Here a sedi- 

 mentary rock in a la}'er from two to three feet in thickness is found ujion 

 the northern face of a clifF of granite. The specimens were unfortunately 

 destroyed by tire, so that thin sections have not been studied, but the field 

 relations are the same as near tlie Palms mine. 



Passing eastward, the next contact between the Southern Complex and 

 the Penokee series is east of Sunday lake. In a test trench, about 200 

 steps east and a short distance south of the north quarter post of Sec. 15, T. 

 47 N., R. 45 W., Michigan, is exposed the contact between the lower green 

 schist and a quartzite, the lowest horizon of the quartz-slate at this point. 

 The schists are finely foliated and contain white quartz veins. The strike 

 of the fibers of the schist does not correspond to that of the overlying suc- 

 cession, but abut against the quartzite at a rather sharp angle. Here the 

 exposure is small and artificial, and the C(jnditions do not appear to have 

 been favorable to the formation of a basal conglomerate. 



In the NE. ^ of Sec. 23, T. 47 N., R. 43 W., Michigan, the rocks of the 

 Southern Complex approach very close to those of the Penokee series, and 

 a beautiful basal conglomerate is ex})osed in the latter. The underlving 

 rock is here a coarse gneissoid granite. It is separated only a few paces from 

 large exposures of a recomposed granitic rock. This recomposed phase of 

 basal conglomerate, in the field and hand specimen, so closely resembles 

 the crystalline rock of which it is the cemented debris that the two might 

 readily be confused; l)ut when examined in thin section thev are readily 

 distinguished, the fragmental character of the one and the thoroughly crys- 

 talline character of the other being apparent. Tliis recomposed rock varies 

 into a conglomerate containing, besides the numerous granite fragments, 

 pebbles of white quartz and a green schist, and then upwai'd into the ordi- 

 nary slate and (piartzite of the district. That the material of this frag- 

 mental rock is here derived from the underlying gneiss and gneissoid 

 granite there can be absolutely no doubt, the major portion of the fragments 

 being precisely like these rocks. 



A short distance west of this point a thin layer of ferruginous lime- 

 stone is found but five steps north of a coarse gneiss. The fact that the 



MON XIX 29 



