G R. Van Rise — Lake Superior Stratigraphy. 117 



Art. XVI. — An Attempt to harmonize some apparently 

 conflicting Vieivs of Lake Superior Stratigraphy •* by 

 C. K. Yan Hise. 



[Read at the Wisconsin Academy of Science, Arts and Letters, Madison, 

 Dec. 30, ]890.] 



In attempting to determine how far the different views held 

 as to Lake Superior stratigraphy are really in harmony, we 

 have as starting planes an upper and a lower horizon. The 

 first of these is the base of the Keweenaw Series. All are 

 agreed that below this series is an unconformity more or less 

 considerable. The lower of these planes lies between the 

 crystalline schist-granite gneiss complex and the overlying 

 elastics. Below this plane is found Irving's Fundamental 

 Complex, Lawson's Contchiching and Laurentian, the Profs. 

 Alexander and N. H. Winchells' Vermilion Lake and Lauren- 

 tian. Whether this plane is definitely fixed by a great uncon- 

 formity will not here be discussed, as the wish is rather to 

 dwell upon points of agreement than those of difference. 

 That it is so fixed is maintained by Irvingf in a series of 

 papers. LawsonJ agrees with Irving that this plane is marked 

 by a great change of conditions of deposition and a probable 

 unconformity in Ontario. Prof. Pumpelly, who has recently 

 made a rather extended trip in western Ontario, acquiesces in 

 this conclusion. Of the extension of these same series in 

 Minnesota, the Profs. Winchell,§ although recognizing this 

 plane as the boundary between two groups of rocks, maintain 

 conformity. Bell|| now stands almost alone in the contention 

 that this lower plane cannot be recognized. In the older work 

 of the Canadian Survey all of the groups of rocks included 

 between the above planes have been placed as Huronian, and 



* This paper is in large measure the same as the part on correlation in a memoir 

 upon the Penokee Series of Michigan and Wisconsin to be published as a mono- 

 graph of the U. S. Geol. Survey. 



For the distribution of the rock-series discussed in this paper, see Irving's 

 Preliminary Geological Map of the Lake Superior Region, 5th Ann. Rept. U. S. 

 Geol. Survey, p. 181. 



f Copper-Bearing Rocks of Lake Superior, U. S. Geol. Survey, Monograph V ; 

 Divisibility of the Archaean in the Northwest, this Journal, III, xxix, pp. 237- 

 249, 1885; On the Classification of the Early Cambrian and Pre-Cambrian Form- 

 ations. U. S. Geol. Survey, Seventh Ann. Rept.; Is there a Huronian Group? 

 This Journal, III, xxxiv, 204-249 ; Explanatory and Historical Note by R. D. 

 Irving to Bulletin U. S. Geol. Survey No. 62. The Greenstone Schist Areas of the 

 Menominee and Marquette Regions of Michigan, by George H. Williams. 



% Report on the Geology of the Rainy Lake Region, Andrew C. Lawsou : Geol. 

 and Nat. Hist. Survey of Canada, Annual Report 1887, part F, p. 141. 



§Geol. and Nat. Hist. Survey of Minn., 16th Ann. Rept., 1887, pp. 365-366. 

 Ibid., 17th Ann. Rept., 1888, pp. 66-67. 



I The Huronian System in Canada. Robert Bell: Trans. Royal Soc. Can., 1888, 

 vol. vi, sec. 4. 



