ON THE GLACIAL ORIGIN OF HURONIAN 

 ROCKS OF NIPISSING, ONTARIO 



REGINALD E. HORE 

 Michigan College of Mines, Houghton, Mich. 



In the early (1846 ff.) reports of the Canadian Geological Survey 

 there appear descriptions by Sir William Logan of a series of non- 

 fossiliferous clastic rocks found on the west shore of Lake Temiska- 

 ming and north of Lake Huron. Logan correlated the rocks of the 

 two localities and gave them the name Huronian. He believed 

 them to be younger than and made up partly of detritus from the 

 Laurentian, and his conclusions have been verified by later observers. 



Recently these rocks have attracted more than local interest on 

 account of the discovery of rich silver veins at Cobalt. As a result 

 of their economic importance the rocks have been subjected to much 

 closer examination than before and many interesting features have 

 been noted. Among these are peculiar characters which are strongly 

 suggestive of the existence of glaciers in Nipissing in early Huronian 

 times. Dr. A. P. Coleman^ who has made a study of these rocks 

 from the standpoint of the glacialist, has gathered evidence from which 

 he concludes that there is no doubt of the glacial origin of the basal 

 conglomerate of the lower Huronian. It is purposed here to present 

 some facts which bear on this question. 



The chief rocks in this district are of the Archean and Algonkian 

 groups. These are separated by a very marked unconformity and 

 the interval was doubtless the greatest which occurred in the pre- 

 Cambrian times. There is no good reason to doubt that for a long 

 period of time the Archean rocks were being worn down by all or 

 any of the erosive agents now active. 



The Huronian series doubtless represent a portion of the secondary 

 rocks thus formed, and they are entirely composed of detrital material. 

 They are conveniently grouped into an upper and a lower series, 



I "The Lower Huronian Ice Age," Jour. Geol., XVI (1908), 149-58. 



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