CHAPTER V Til. 



By O, E. Van Hise. 



THE EASTERN AREA. 



Introduction. 



Section I. Tlie Iron-bearing member. 



Distribution. Petrograpbic.il oh.aracter. Mingled fragmental and nonfragmental sedimentation. 

 Probability of ore deposits in the eastern .area. Talinlatiou of petrographical observations. 

 Section II. Kragraental rocks soutb of tbe Greenstone-conglomerates. ^ 



Geographical distribution. Petrographical character. Tabulation of jtetrographical observa- 

 tions. 

 Section III. The Greenstone-conglomerates. 



Distribution. General (-liaraiteristics. Origin of tlie Greenstone-conglomerates. Tabulation 

 of petrographical observations. 

 Section IV. Fraginental and ferruginous rocksnortliaud east nf the Greenstone-conglomerates. 



Geographical distribution. Surrounding rocks. Continuation of the belt east and west. Struc- 

 ture of the belt. General jjctrographical character. Mingled Iraginental and nonfragmental 

 sediments. Coarsely fragmental rocks. Tabul:ition of petrographical observ.atious. 

 Section V. The Greenstones. 



The main area. The area in Sees. 20, 29, and 30, T. 47 N., R. 43 W., Michigan. The area in 

 Sees. 24, 13, 14, and 15, T. 47 N., R. 44 W., Michigan. 

 Section VI. Stratigraphy. 



Lithological evidence as to equivalence with the main Pcnokee area. Stratigraphical evidenc 

 as to equivalence with tlie main Penokee area. Relations of tlie lielts of the eastern area to 

 each other. Great width of parts of the eastern area. Tli<' southern dips. Sequence of events. 

 Mingled fragmental and nonfragmental sediments. Sunuiiary. 



INTRODUCTION. 



The area east of the center of T. 47 N., R. 44 W., Michigan, or 

 rouo-hly east of the Little Presque Lsle river, (hft'er.s from the simple suc- 

 cessions described in the previous chapters in many important points. As 

 will be seen later, the differences are due to the fact that this area was the 

 center of great contemporaneous- volcanic activity. Consequently the suc- 

 cession includes large thicknesses of volcanic tuffs and lava flows. These 



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