EVIDENCE OF TWO SYSTEMS IN THE " HURONIAN." 113 



as "the Huronian group," tested and proved, is an act of hasty generaliza- 

 tion as difficult to reconcile with his acknowledged sagacity and learning as 

 his hypothesis is difficult to reconcile with the facts. Yet it is apparent that 

 in his successive publications he made progress toward true conceptions ; 

 and had it not been for early prepossessions, derived from the geology of 

 Wisconsin, he must have obtained the simple clew which would have led to 

 a solution of all the difficulties which beset him. 



We think it may be concluded that the exceptional and apparently un- 

 tenable views inculcated by Professor Irving should not prevent us from 

 accepting the abundant evidence which we have of the existence of two sys- 

 tems of strata between the Potsdam sandstone and the fundamental gneiss. 



The evidence of two systems could be traced much further. It could be 

 pointed out in the Penokee and Gogebic regions, and in the Marquette and 

 Menominee districts. In respect to the Marquette district, this was vaguely 

 discerned by Irving, as it had previously been by Brooks,* Rominger and 

 Hunt ; but Irving, of course, in identifying the Vermilion with the Gogebic 

 and Penokee and part of the Marquette series, was misled by his antecedent 

 assumption that it was a folded condition of the Auimike. 



Views of Lawson. — Much more clearly has the existence of two systems 

 and the non-Huronian character of the older one been discerned by Dr. A. 

 C. Lawson, whose field of work for several years was in the district of Lake 

 of the Woods and Rainy lake, contiguous to Minnesota, and whose geological 

 sagacity is most creditably reflected in his two reports.* After completing 

 his field-work on the Lake of the Woods, he felt it incumbent on him to 

 propose a new name for the assemblage of older folded schists, which had 

 by his predecessors been denominated '^ Huronian." From his introductory 

 remarks we make the following quotations : 



" The schistose belt of the Lake of the Woods appears to me to differ from the typ- 

 ical Huronian of Sir W. Logan, both lithologically and in other respects. The typical 

 Huronian of Logan is, from his description of it, essentially a quartzite series, in 

 which the quartzites are true indurated sandstones [f]. The schistose belt of the Lake 

 of the Woods is not so characterized. Quartzites form an extremely small proportion 

 of the rocks of the Lake of the Woods, and they are only local developments in for- 

 mations of mica schist and felsite schist. Bedded limestones are characteristic of 

 Logan's typical series. On the Lake of the Woods there are, so far as I have been 

 able to determine, no bedded limestones, the nearest approach to them being small 

 segregated bands of dolomite of the character of veinstones. These two differences 

 alone are suflSicient to throw doubt on "the equivalence of the two series, if lithological 

 character is to be regarded as an aid to geological classification. There are, however, 

 other differences. The basal conglomerate of Logan's Huronian [J] on Lake Temis- 



*GeoIogy of Lake of the Woods, Canad. Geol. Rep. for 1886, Document CC ; and Geol. of Rainy 

 Lake, Canad. Geol. Rep. for 1888, Document F. 



tThis is Irving's generalization, as already shown. 



Jin point of fact the "basal conglomerate" in general was sometimes the upper and sometimes 

 the lower slate conglomerate, and was always separated from the gneiss by an unknown interval or 

 by a bed of greensione sciiist. Uu Lake Temiscaming it was the lower slate conglomerate (see 

 ante, p. 102). 



