84 THE MAlfQUETTE IKON -BEARING DISTRICT. 



older tliaii the gTiuiite, ami \'et tlie author places the granite in tlie oldest 

 forniatiou of the series. Naturally, if tlie granites as erui)tive rocks pro- 

 duced the folding of the Huronian beds, tliey must be the youngest of 

 all the rocks occurring in the series, and can not possibly be the oldest in 

 their present [)osition. The author explains this anomaly in the following 

 Avords (pp. 22-23): 



The granites, considered in tbeir present .surface position, are, in relation to 

 the stratified sedimentary rocks of the Huronian series, actually the younger rocks. 



* * * The hypothesis of their contemporaneous eruption is therefore well admis- 

 sible. But supposing this to have been the case, one may ask, Of what nature, theu, 

 was the substratum on which the Huronian sediments were deposited? I answer, 

 Nothing contradict.'j the possibility of their depo.sition on a surface of granite already 

 formed; it is even probable to me that it has been so; but if we reflect upon the high 

 degree of plasticity and the almost perfect liquefaction which the couuerued rocks 

 subsequently underwent, and upon the dislocating forces, causing the softened 



* * * masses to intermingle almost chaotically, we can no more wonder that the 

 traces of the originally existing former relative position of the rocks among themselves 

 are greatly obliterated. 



The meaning of this is that the Huronian rocks were laid down 

 upon a crust of granite which had not become rigid. Subsequently 

 the granite rose and was erupted through the beds that had been piled 

 upon it. 



The "granitic group" contains a great many beds of green schists, 

 hornblende-rocks, and diorites, but the granites are the predominant rocks. 

 The "dioritic group," on the other hand, is made up of a large succession of 

 .schistose beds interstratified with massive belts of diorite almost identical 

 'Chemically with the schistose beds. The lines of demarcation between the 

 granitic and the dioritic "groups" are not sharp; indeed, as the author 

 declares, they are " artificial lines of demarkation for the convenience of 

 description." "I do not intend to indicate by these subdivisions (into 

 groups) separate, distinct epochs. ' 



The various crystalline hornblende-rocks associated with the granites 

 •are considered to be remelted Huronian sediments. Those more remote 

 from the eruptive are much altered, but the author believes that he can 

 .detect in them the sedimentarv structure. Throuo'li them have been intruded 



