110 A. WINCHELL — A LAST WORD WITH THE HUROXIAN. 



deposits. In its various exposures it reveals all the characters of the ver- 

 tical pseudo-Hurouian schists north of Lake Superior which stand under 

 the Animike. The evidence of this is spread on the pages of the Minnesota 

 annual reports. These are the system of vertical strata which graduate 

 conformably into crystalline schists and gneisses — just as Logan, Bell, and 

 Macfarlane describe the vertical schists north of Lake Superior. Besides 

 standing proximate to the crystalline beds, they are lithologically the same 

 from Thunder bay to Vermilion lake — greenish, gnarled, silicious slates, 

 often conglomeratic, but less so westward, passing to argil lites, either char- 

 acteristic, graywackenitic, or silicious ; often, also, couglomeratic, as seen 

 characteristically about Ogishke-muncie lake, and felsitic and poroditic 

 schists giving evidence, greater or less, of intense metamorphic, perhaps 

 eruptive, action, alternating frequentl}^ with beds of decayed diabases and 

 intersected by well preserved diorites and diabases. If the identification of 

 the Vermilion iron series of schists with those of Thunder bay is established, 

 there can be no more uncertainty in tracing the identification to the east 

 shore of Lake Superior, and thence, as we shall show% into the typical Hu- 

 ronian region. 



Vieivs of Irving. — But the late Professor Irving presents obstacles to such 

 identification. He claims, as we do, that the Animike is the characteristic 

 Huronian of Lake Superior; but he claims also that the vertical iron-bear- 

 ing series of Vermilion lake is Huronian.^ The iron-bearing schists are 

 vertical and the Animike varies little from horizontal. The iron-bearing 

 schists maintain their verticality as far east as Knife and Ogishke-muncie 

 lakes. They are vertical at their exposure north of Gunflint lake. Schists 

 lithologically identical are vertical at Thunder bay and on the east shore of 

 Lake Superior. The theorem which Professor Irving attempted to demon- 

 strate was the continuity of the vertical and the horizontal slates. He 

 begins by attempting to invalidate, in part, the statements of Dr. Bell re- 

 specting the so-called Huronian north of Lake Superior : 



" An examination of Bell's various reports upon the region north of Lake Superior 

 seems to make it evident that in separating the Huronian from the gneisses of the 

 region his only criterion has been the schistose or non-schistose character of the rocks. 

 All rocks of strongly schistose character seem to have been regarded at once as Huro- 

 nian. At times there seems to have been some difficulty, as, for instance, when mica 

 schists have been found to grade directly into gneisses. That some of the rocks in- 

 cluded within Bell's schistose belts are lithologically like the original Huronian there 

 seems to be no doubt; but, on the other hand, there is reason to believe that schistose 

 rocks do not occur as dependencies of the older gneisses. My own experience, indeed, 

 leads me to believe that mica-schists, hornblende-schists and chlorite schists do occur 

 in such relations [f]. I regard it, then, as a question still entirely open to investigation 



*Archeai. Formations of the Northwestern States, Fifth Ann. Rep. U, S. GpoI. Siirv., 188:^, pp. 

 206-208. Compare, also, Third Ann. Rep. Wis. Geol. Surv., 1880, p. 171; and Monog. V., U. S. Geol. 

 Surv.. 1883, pp. .S99, 417. 



t But the two former have seldom been included in the Lake Superior Huronian. 



