392 A. WTNCHELL — RESULTS OF ARCHEAN STUDIES. 



over by Professor Irving's survey. Thin sections of the rocks collected 

 have been made and examined in detail. The rocks were found to be crys- 

 talline schists. Still further to the west is the Vermilion lake series.* 



It was Professor Irving's opinion that the fragmental and jaspery rocks 

 bearing ore at Vermilion lake, which are nowhere directly in contact with 

 the Animike rocks, are probably their equivalents. Dr. Winchell admitted 

 that the Animike rocks, besides exhibiting true bedding in certain places, 

 have a cleavage. Professor Irving believed that the section upon the board 

 I tig. 7) represents an intensely squeezed complex series (instead of a simple 

 conformable one 100,000 feet thick), the cleavage of which is secondary, just 

 as described by Dr. Winchell as occurring in the Animike rocks. 



The reasons in detail for the above correlation would occupy too much 

 time to present to the Society. In general it was based upon lithological 

 likeness, not only of the- masses of the rocks as a whole, but of their individ- 

 ual members. It was based on the unlikeness which the Animike series and 

 the ore-bearing rocks and associated elastics of Vermilion lake have to tin 

 crystalline schists below the Animike and north and south of the Vermilion 

 rocks mentioned. It was based upon the comparison of these two groups 

 with the other iron-bearing series of Lake Superior. I can only refer you 

 to Professor Irving's elaborate memoirs for the many facts upon which he 

 rested his conclusion. 



Finally, I would say that Professor Irving's ideas as to the complication 

 of the structure of northeastern Minnesota were quite different from those of 

 Dr. Winchell. Dr. Winchell holds that the structure in this region is ex- 

 ceedingly simple. It seems to me that the geological history of the Scottish 

 Highlands is instinctive in considering the geology of northeastern Al inix- 

 Bota. It was believed many years ago that the structure of the Highlands 

 was understood, but recent study has shown that the old ideas were largely 

 false; that its real structure is far more complicated than was believed; that 

 it is immensely complicated. The recent study of the Appalachian region 

 is teaching an exactly similar lesson. Professor Irving believed that the 

 crystalline series in northeastern Minnesota is the most complicated in its 

 structure of all of the regions about Lake Superior. 



Professor Winchell: I trust it will not be assumed by this audience 

 that I undertook to attack Professor Irving's authority on the nature of any 

 kind of rock : least of all have I asserted or insinuated that he was nol 



capable of determining whal is mica schist or crystalline Bchist. That i- 

 far aside from anything which I implied. - ] The statement upon which my 

 friend Van Rise's assumption is grounded is simply my allegation that on 



Por ili«- distribution of the formations under discussion .■>- lerstood by Professor Irvin 



7th Annual Report, U. S Geol. Survej >*P»P ">. 



| Por my estimate of Professor irving's abilities and servioi leenth . I mi. /.'. p \l 



p. i ii, note. 



