^^w^ 



52 



BULLETIN OF THE 



sometimes standing nearly vertical. It was not observed in contact with 

 the " diorite," but wc feel that the conatant uptilting of the jasper and 

 associated schists when near these intrusive rocks is good evidence that 

 the *'diorite" eruption was later than that of the jasper. The nptilting 

 of the jasper was well seen on a hill north of the Jackson mine, where 

 it was found, standing nearly vertical, within one hundred feet of the 

 " diorite." 



Granite, Gneiss, and Quartzite, 



The relation of the granite and its associated foliated rocks to the 

 schists of the Iron district is a problem of great geological importance. 

 The diverse views have been given on preceding pages, and it is not 

 necessary to repeat them here. The first-mentioned rocks have been 

 accepted by the Canadian geologists (in part at least), as well as by 

 most American ones, as the direct equivalents of the Laurentian 

 formation of Canada, while the latter is in the same way accepted 

 as the equivalent of the liuronian. Without going into the question 

 of the expediency or right of establishing geological ages upon any 

 other basis than that of organic remains, it is a fair question of in- 

 quiry whether the " Laurentian" of Lake Superior is older or younger 

 than the " Huronian.'' Whose observations were the nearest correct, 



those who claim that the granite is intrusive in the schists, or 

 those who hold that it unconformably underlies thcml On one side 

 we have the statement of direct intrusive contact ; on the otlier, the 

 evidence afforded by the fact that the strike and dip of the foliation of 

 the two rocks are unlike, the two formations never having been seen 



in contact. 



It is now time to give the facts observed by us. 



North of Kepublic, })y the side of the railroad, a few rods from the 

 depot, the grauite (82) (Laurentian of Brooks) shows its intrusive char- 

 acter by its containing fragments of schist (83) in it, and by its cutting 

 the main body of schist. These schists are micaceous, hornblendic, and 

 chh)ritic, with a nearly" north and south t^trike, the foliation of the 

 granite coinciding with it. Northwest of the track, near the above- 

 mentioned locality, the inclusions in the granite are well marked, the 

 foliation of the granite striking S. 20° E. Southeast of Republic Moun- 

 tain, separated from the supposed *' Huronian " by a narrow ravine, 

 the granite was observed in contact with a garnetiferous actinolite rock, 

 beautifully banded and contorted (No. 97, p. 48). While this appears to 

 us to be identical with the '41uronian" rocks, a few rods away, resembling 



