134 Van Hise — Attempt to harmonize some apparently 



the Keewatin — probable equivalent of the Lower Marquette. 

 It, however, appears that in this part of Ontario somewhat dif- 

 ferent conditions prevail from those which occur on the south 

 shore of Lake Superior. The irruptive contact found between 

 the Coutchiching and Laurentian is also present between the 

 Lauren tian and Keewatin. Upon the south shore it does not 

 appear that granitic eruptions of any magnitude have taken 

 place since the beginning of Lower Marquette time, although 

 in the Felch Mountain Iron-Bearing Series occurs one granitic 

 dyke of considerable size, and it is not impossible that in the 

 Marquette district itself some of the lower members truly 

 belonging to the iron series are cut by granitic eruptions. 



We then have in the Lake Superior region the provisional 

 arrangement for the Pre-Cambrian rocks on page 137. 



Nomenclature. — There still remains the question of nomen- 

 clature. A sufficient number of terms have been suggested, 

 and it is only necessary to ascertain which have prior right and 

 best answer the needs of geology. The work of Lawson has 

 made it clear that the old Laurentian must be subdivided. 

 He retains for the igneous portion of it Laurentian, and pro- 

 poses for the lower crystalline schist series — which he sup- 

 poses to be fragmental, but which if so in most cases does not 

 now reveal at all its original clastic character — the term 

 Coutchiching. The rock series represented by these terms, as 

 has been seen, cover large areas in Minnesota, Michigan, and 

 Wisconsin, and the relations between the two are here the 

 same as in Ontario. It then seems desirable to apply them 

 broadly to the Fundamental Complex of the south as well as 

 the north shore of Lake Superior. The only other term intro- 

 duced for this part of the column is the Yermilion Series, 

 equivalent to Coutchiching, proposed by the Professors Win- 

 chell. The latter term has, however, unquestionable priority 

 and has been more detinitely defined.* 



The term Keewatin was defined by Lawson to cover a series 

 of elastics about the Lake of the Woods, and was chosen by 

 the Professors Winchell for the Yermilion Lake iron-bearing 

 series, which was believed by them to be the equivalent of the 

 Original Keewatin. If this conclusion were demonstrated, it 

 would seem proper to adopt this term to cover not only the 



* In this article. Yermilion Series always refers to the iron-bearing rocks and 

 associated elastics of Yermilion Lake. This term was thus first loosely applied 

 by Irving (Preliminary Paper on an Investigation of the Archean Formations of 

 the Xorthwestern States. R. D. Irving: 6th Ann. Report, U. S. GTeol. Survey, pp. 

 177-242.) Later it was used by the Professors Winchell to designate an under- 

 lying series of crystalline schists. For this series, however, Lawson had previ- 

 ously proposed the term Coutchiching. (The Internal Relations and Taxonomy 

 of the Archean of Central Canada. Andrew C. Lawson. Bull. Geol. Soc. of Amer- 

 ica, vol. i, p. 183, 1890.) 



