ARCHEAN GRANITES. 261 



as exposures closer and closer to the main granite mass are examined, as 

 described and explained on p. 156 et seq. It is not uncommonly found that 

 the greenstone is schistose, and the granite dikes are seen to follow the 

 schistosity, proving its development prior to the intrusion of the granite. 

 The granite also includes fragments of schistose greenstone. 



Relations to other intrusive rocks. — As stated above, the granite areas 

 were not studied in great detail, but a sufficient number of observations 

 were made to show that the granite is cut by both acid and basic dikes. 

 The basic rocks are cut by acid dikes, as is shown in the photograph repro- 

 duced on PI. XIII, B. The normal white to gray granite has been cut by a 

 red-weathering granite which traverses it in dikes, but the period of intru- 

 sion of these later red granites has not been determined, even approximately. 



The granite of Trout, Burntside, and Basswood lakes is evidently 

 younger than the Ely greenstone, which it cuts, includes, and metamor- 

 phoses. Dikes, offshoots from it, are found following the schistosity of the 

 greenstone and including these schists. Hence it was certainly intruded 

 subsequent to the formation of the schistosity in the greenstone. This 

 schistosity was produced primarily as a result of the folding which took 

 place subsequent to the deposition of the iron formation and which caused 

 the folding of this iron formation. Therefore it is concluded that this 

 granite is younger than the iron-bearing formation, although the jasper is 

 in no place cut by dikes which can be connected directly with the main 

 masses of the granite. 



This granite is not clearly recognizable in the pebbles in the overlying 

 Lower Huronian sedimentary series, but where this series comes closest to 

 the granite its relation's are sufficiently clear. Thus, for example, dikes of 

 this granite, as in sec. 16, T. 64 N., R. 9 W., north of Moose Lake, are 

 found to cut the greenstones underlying the sediments, but never to pass 

 the contact and penetrate the sediments, although the dikes are numerous 

 near the contact. Hence the conclusion is reached that the granite of Trout, 

 Burntside, and Basswood lakes is older than the Lower Huronian sediments. 



