conflicting Views of Lake Superior Stratigraphy. 133 



The equivalency here shown is a long step in understanding 

 the equivalency of other rocks in the Lake Superior basin. 



The Marquette Series. — As in the Marquette district we 

 have already discussed in a general way the succession, it need 

 here be merely repeated. It is as follows : At the base is a 

 gneiss-granite complex, Lawson's Laurentian, and this is asso- 

 ciated with crystalline schists which are like Lawson's Coutch- 

 iching. The relations between these two classes are also those 

 described as occurring between them in Ontario. In ascending 

 order follow the Lower and Upper Marquette, having the 

 lithological characters and relations above described. 



The Menominee and Fetch Motmtain Series. — Passing now 

 to the Menominee and Felch Mountain districts, our informa- 

 tion is less exact. It is, however, clear that in both of these 

 areas we have the Fundamental Complex ; that is, the granites 

 and gneisses associated with crystalline schists having the usual 

 " irruptive contacts " — the equivalents in every respect of Law- 

 son's combined Laurentian and Coutchiching. Above this 

 complex Prof. Pumpelly, with whom this whole subject has 

 been discussed and who has great familiarity with the entire 

 Lake Superior region, suggests as exceedingly probable that in 

 the Felch Mountain Iron-Bearing Series only the equivalent of 

 the Lower Marquette occurs, the upper series, if it once existed, 

 having been removed by erosion ; while in the Menominee 

 district both representatives of the Lower and Upper Marquette 

 are present. The Menominee proper — that is, that part of the 

 area which includes the Chapin, Ludington and Norway mines ; 

 those in which a cherty limestone is found — are Lower Mar- 

 quette, while the western district, including such mines as the 

 Commonwealth, Florence and many others occurring in the 

 upper black slate are Upper Marquette. That between these 

 two is an unconformity is not proven, but it is a probability to 

 be sought. 



The Black River Falls Series. — The Black Eiver Falls 

 Iron-Bearing Schists of Wisconsin have no such structural rela- 

 tions as to enable one to determine their position. They are, 

 however, thoroughly crystalline schists and are in vertical atti- 

 tude. On these grounds they are placed as the equivalent of 

 the Lower Marquette. 



In the districts about the Lake of the Woods and Kainy 

 Lake, so well described by Lawson,* we have apparently, as at 

 Felch Mountain only the two lower series of the general suc- 

 cession, the Coutchiching-Laurentian complex ; and above this 



* Report on the Geology of the Lake of the Woods Region, Andrew C. Lawson, 

 Geol. and Nat. Hist. Survey of Canada, Ann. Rept. 1885, vol. 1, new series, part 

 CO, pp. 1-151. Report on the Geology of the Rainy Lake Region, Andrew C. 

 Lawson: Geol. and Nat. Hist. Survey of Canada, Ann. Rept. 

 1-190. 



