CHAPTER IX 



By C. R. Van Hise. 



GENERAL GEOLOGY OF THE DISTRICT. 



Section I. Flexurps and faults. 



Curvinji; of tlie layers. Fault at Bad rivpr. Fault it Potato river. Fault iu the Eastern area. 

 Section II. Structure. 



TLc Southern Complex. The Cherty limestone and Quartz-slate members. Unconformity between 

 the Southern Complex and the overlying Cherty limestone and Quart/slate. Unconformity 

 lietween the Cherty limestone and the Penokee series proper. The Iron-bearing and Upper slate 

 memliers. The unconformity at theliase of the Keweenaw series. The Eastern sandstone and 

 the uniiniformity at its base. Resumi^ of geological history. Why the district is given a sepa- 

 rate memoir. Dejdh and luetaniorphism. 

 Section III. Correlation. 



Equivalency of Penokee series proper with .\nimikie series. Equivalency of Penokee and Mar- 

 quette series. Comparison with other series. 



SECTION I.— FLEXURES AND FAULTS. 



Curving of the layers. — The ourvino' ot'tlie layers of the Penokee series 

 subordinate to its uplifting as a whole, has in the main l)een of so gentle a 

 nature that thev have not been broken. At the west side of R. 3 AV., Wis- 

 consin, there are several xer^ .sharp bends in the Quartz-slate and Iron- 

 bearina" members. There is a somewhat sudden turn in the trend of the 

 layers near the middle of R. 2 W., Wisconsin. West of Sunday lake the 

 nearest known rock in the iron formation is about one-fourth of a mile 

 south of the north (juarter post of Sec. 17, T. 47 N., R. 45 W., Michigan. 

 East of the lake tlie southern boundary of the iron formation is one-f(un-th 

 mile north of the soutliAvest corner of Sec. 10 in the same township. (PI. xrt.) 

 Consequently the iron belt suddenly swings from an east and west course 

 north more than a half mile in a distance of li miles. Li the northwestern 



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