388 THE PENOKEE IRON-BEAEING SERIES. 



exposures found indicate a northern trend to the beh. In the other direction 

 — that is, east of T. 47 N., R. 43 W., I\Iichigan, the beU bends southward, 

 entering T. 47 N., R. 42 W., Michigan, in Sees. 18 and 11), and from 

 this place describes approximately the arc of a circle, the easternmost point 

 of which is in the center of Sec. 28. 



Surroundinff rocks. — The rocks south of the belt vary in their charac- 

 ter. In Sec. 14, T. 47 N., R. 44 W., Michigan, this rock is a porphyrite, of 

 such a nature as to indicate that it is a surface flow. Through the greater 

 part of the distance, from the west line of Sec. 13, T. 4-7 N., R. 44 W., 

 Michigan, to the northwest part of Sec. 23, T. 47 N., R. 43 W., Michigan, 

 the greenstone-conglomerate is the nearest known rock. It is to be observed 

 that here is a strip of country, in some places as much as half a mile wide, 

 in which no exposures are known between the fragmental rocks and the green- 

 stone conglomerates ; therefore there may be between these two formations 

 another belt. From the north quarter post of Sec. 23, T. 47 N., R. 43 W., 

 Micliigan, to the eastern end of the belt, its southern boundary is the under- 

 lying complex of hornblende-schists and mica-schists, gneisses and granites. 

 Here there is little doubt that these rocks are the immediately underlying 

 ones ; for in several ])laces in the fragmental series are basal conglomerates 

 and recomposed granites, which are chiefly composed of debris derived 

 from the crystalline rocks immediately to the south, while in one sec- 

 tion the actual contacts between the fragmental and noiifragmental rocks 

 are seen. 



The rocks north of the fragmental belt, from its western end to near 

 the center of Sec. 18, T. 47 N., R. 42 W., Michigan, are the greenstones of 

 tlie overlying Keweenaw series. In two places the fragmental rocks are 

 found very close to the greenstones, and it is therefore probable that these 

 rocks lie immediately to the north of the fragmental belt. East of the center 

 of Sec. 18, T. 47 N., R. 42 W., Michigan, no exposures are found nortlieast 

 of tlie belt except in Sec. 28, where the Eastern sandstone is found in hori- 

 zontal position, unconformably overlying the fragmental belt of rocks 

 under discussion. 



Continuation of the belt east and west. — Whether this belt continues east 

 and west of the area outlined for it upon PI. xiii is an open question. West 



