THE EASTERN AKEA. 389 



of the westernmost exposure of the beU, in the north part of Sec. 14, T. 47 

 N., R. 44 W., Michigan, is the valley of the Little Presque Isle, in which 

 there are uo exposures. About a mile west of the Presque Isle, and 1^ 

 miles west of the exposure referred to, is developed, by a test pit, rocks 

 which are almost purely uonfragmental sediments, but which have mingled 

 Avith them some fragmental sedimentation. It is doubtful whether 

 the belt under discussion ought not to be carried west to tliis pit, and from 

 here be continued westwai'd until it merges into the iron-bearing belt of the 

 main area. The eastern end of the belt, in Sec. 28, T. 47 N., R. 42 W., Mich- 

 igan, is very narrow. Between the gneisses and granites and the horizontal 

 Eastern sandstone are but a few score of feet, or at most one or two hundred 

 feet. There is, then, but little room at surface for the belt under considera- 

 tion. Whether southeast of the center of section 28 it is entirely covered 

 by the Eastern sandstone or not we have no means of knowing. In 

 case the Eastern sandstone does thus overlap, we have here the eastern 

 end of the Penokee series. 



Structure of the belt. — The exposures in T. 47 N., R. 44 W., Michigan, 

 and most of those in Sec. 28, T. 47 N., R. 42 W., Michigan, are without 

 structure ; but the most of the exposures in T. 47 N., R. 43 W. and 42 W., 

 Michigan, are clay-slates or graj'wacke-slates, which have well defined 

 strikes and dips. In the few outcrops in T. 47 N., R. 42 W., Michigan, in 

 which this dip is known, it is northeast. These dips are not indicated 

 upon the map because they are not so accurately known as could be 

 desii-ed. However, at one exposure in the soiitheast part of Sec. 20, the 

 dip is clearly northeast, while the statement of the explorers who 

 have done the test pitting generally agree with the above statement as to 

 a northeasterly dip. Jn T. 47 N., R. 43 W., Michigan, however, Avhere the 

 exposures are the most numerous of anywhere in the belt, a portion of 

 them dip north and a portion south, the greater number of exposures hav- 

 ing the latter inclination. These apparent southern dips are of great impor- 

 tance, because these are the only known ledges with a southern dip which 

 unquestionably belong to the Penokee series. 



The more ferruginous of these rocks — that is, the few exposures which 

 approach a jasper — have a northern dip. The rocks which show a southern 



