128 Van Hise — Attempt to harmonize some apparently 



The Original Huronian Series. — Passing now to the Orig- 

 inal Huronian.* Shall this series be correlated with the Upper 

 or Lower Marquette, or is it the equivalent of both ? A 

 careful help! and laboratory study of the rocks of the Original 

 Huronian has shown it to consist in great part (1) of f rag- 

 mental quartzites, the induration of which has been caused by 

 the deposition of interstitial silica ; (2) of gray wackes and 

 graywacke-slates (at time, conglomeratic — Logan's slate-con- 

 glomerates), the induration of which is due to the deposition 

 of interstitial silica and metasomatic changes in the feldspar ; 

 (3) of cherty limestones ; and (4) of eruptives. So far as yet 

 known an iron-bearing belt is not there largely developed, 

 although at certain localities rocks belonging to this formation 

 are found. 



In its readily recognized fragmental character, in its gentle 

 folding, and in the greatness of the break between it and the 

 granite-gneiss complex, the Original Huronian is much more 

 nearly analogous to the Penokee, Upper Marqnette and 

 Animikie than to the Lower Marquette and Lower Yermil- 

 ion iron-bearing series. In the order of succession of its 

 subordinate members it cannot be said to correspond very 

 closely with either the Upper Marquette and Animikie or the 

 Lower Marquette and Lower Vermilion Lake. It, however, 

 seems to us that its unmetamorphosed character is a guide 

 of some importance. As pointed out by Mr. McKellar,t the 

 intense folding to which the Vermilion Lake and Kaminis- 

 tiquia Series have been subjected must have preceded the much 

 more gentle synclinal movement which formed the basin of 

 Lake Superior. That no violent squeezing has occurred since 

 the beginning of Animikie time is known to be true of the 

 Lake Superior Basin, and this being true, it seems exceedingly 

 probable that the gently folded rocks of Lake Huron belong 

 with those of like character about Lake Superior. If this is 

 not the case, the intense dynamic movements which produced 

 the closely folded rocks of jSTortheastern Minnesota and Ontario 

 must have lost their force before reaching the area about Lake 

 Huron, and this region must have escaped any serions folding 

 for a longer time than any other closely studied part of the 

 earth's crust. 



* The Original Huronian only is here compared with the series about Lake 

 Superior because it is the area to which the term was first applied, and also be- 

 cause it has been more thoroughly described and mapped than any other area in 

 Canada designated by the term Huronian. How far other areas of rocks in- 

 cluded under this term by the Canadian Survey in the past are the equivalent of 

 this Original Huronian area is difficult to determine. That many other areas are 

 less Huronian than the original area I would not pretend to say. In this con- 

 nection see, The Huronian System in Canada, by Robert Bell, Trans. Royal Soc. 

 Can., vol. vi, sec. 4, pp. 3-13, 1888. 



f L. c. p. 88. 



