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University of California Publications in Geology [Vol. 10 



group of variously named formations on the northwest side compris- 

 ing the Seine slate, quartzite and conglomerate, the Knife slates, 

 Agawa iron formation, and Ogishke conglomerate of the northwest 

 side. It follows also from the recent work of Allen and Barrett 5 that 

 the Copps Formation, the Michigamme slate, the Bijiki iron forma- 

 tion, and the Goodrich quartzite of the south side are the correlatives 

 of the Animikian of the northwest side of Lake Superior. 



North of Lake Huron. — Coming now to the Canadian territory ex- 

 tending from Lake Huron to Lake Temiskaming, there are three gen- 

 eral districts in each of which the sequence of the pre-Cambrian rocks 

 has been for the most part clearly established. These are the north 

 shore of Lake Huron, Sudbury, and Lake Temiskaming. In all three 

 districts it is now agreed that in post-Keewatin time there were two 

 distinct periods of granitic invasion. It is also undisputed that one 

 of these invasions occurred in time long antecedent to the deposition 

 of the great body of sedimentary rocks now called the Temiskamian 

 (Sudbury) series, and that the second period of granitic invasion is 

 later than that series. This fact was well known to Logan and pre- 

 cisely described by him in the following words : 



The intrusive granite occupies a considerable area on the coast of Lake Huron, 

 south of Lake Pakokagaming. It there breaks through and disturbs the gneiss 

 of the Laurentian Series and forms a nucleus from which emanates a complexity 

 of dykes, proceeding to considerable distances. As dykes of a similar character 

 are met with intersecting the rocks of the Huronian Series (Temiskamian of Miller 

 and Knight), the nucleus in question is supposed to be of Huronian age, etc.o 



It seems clear that the older of these granites is what Logan called 

 Laurentian and that it is older than the Temiskamian (Sudbury) 

 series. The later granite cuts the Temiskamian, as is described by 

 Logan, Miller, Coleman, and Collins. In the Sudbury district the 

 Temiskamian (Sudbury) series is invaded by granite and the con- 

 glomerate of the series contains boulders of granite, although the 

 basement is not exposed. In the Cobalt district the Temiskamian 

 rests on the eroded surface of the Laurentian granite and is itself in- 

 vaded by the Lorrain granite. 



In a recent paper Collins 7 has shown that the later, or Killarney, 

 granite also cuts the Bruce series. 



Op. cit. 



« Geology of Canada, p. 58, 1863. 



1 Geol. Survey of Canada, Mus. Bull. no. 22, 1916. 



