THE EASTERN AREA. 361 



beds are not paralleled by any that are found in the western area. Fur- 

 ther, this volcanic material has greatl}' disturbed the normal succession of 

 belts in the district, so that it is difficult ta certainly correlate the forma- 

 tions east of the Presque Isle with those west of it. Another point in 

 wliich this area differs from the western area is that in one place the 

 relations of the horizontal Eastern sandstone to the Penokee series can be 

 made out. The subject is divided into the following sections: The Iron- 

 bearing- member; the fragmental rock south of the greenstone-conglomer- 

 ates; the greenstone-conglomei-ates; the fragmental and fen-uginous rocks 

 north and east of the greenstone-conglomerates; the greenstones; stratig- 

 raphy. 



SECTION I.— THE IRON-BEARING MEMBER. 



Distributmi. — The rocks naturally and artificially exposed east of the 

 Little Presque Isle river which can certainly be referred to the Iron-bear- 

 ing memljer, although quite numerous, do not form as contiiuious a belt as 

 do similar rocks to the westward. Through the east part of T. 47 N., R 

 44 W., Michigan, and the west mile of T! 47 N., R. 43 W., Michigan, the 

 gaps between the exposures are in each case about a mile, while in one 

 instance a gap of 2 miles occurs. East of this latter point prospecting has 

 shown rocks of the Iron-bearing member to be practically continuous for 

 about 4 miles; i. e., from the southwest part of Sec. 20 to the northwest 

 part of Sec. 23, T. 47 N., R. 43 W., Michigan. East of the latter point no 

 rocks are found which certainly can be referred to the Iron-bearing 

 member. 



In the easternmost section of the western area of the Iron-bearing l)elt 

 the exposures spread over a horizontal distance greater than at an}- other 

 locality in the whole Penokee series, extending as they do from the north- 

 east part of Sec. 21 to the northwest part of Sec. 15, T. 47 N., R. 44 W., 

 Michigan, a distance of nearly a mile. The most of the exposures of this 

 section are south of a huge ridge of basic eruptives, some of them being in 

 contact with this rock. North of this eruptive, and about a half mile north 

 of the nearest exposure of iron-bearing rocks to the southward, are ex- 

 posed by a test pit rocks wliich undoubtedly belong to the lion-liearing 

 member. The only othci- localitv wliere the thickness of tlie l)e]t ap- 



