io6 



subordinate areas of grey or dark gneiss. 

 Between mileage 59 and 60 the rock is a 

 massive red granite, gneissoid in part and not 

 often banded. The next two and a half miles 

 disclose banded gneisses, many of the dark bands 

 of which are as basic as certain Keewatin horn- 

 blende schists. Between mileage 62.5 and 64 a 

 coarse, massive, hornblende granite is well 

 exposed. Dikes of fresh diabase, resembling 

 the olivine diabase dikes of the Sudburv nickel 

 area, are to be seen between mileage 56 and 64. 

 At Doherty, mileage 64, the first ex- 

 posures of pre-Cambrian sediments make 

 their appearance. A series of conglomerate, 

 greywacke, and slate-like greywacke, resting in 

 horizontal position, lie unconformably on the 

 massive, hornblende granite last mentioned. 

 This series of sediments, which is known as 

 the Cobalt series, holds numerous pebbles and 

 boulders of the underlying" granite. Contacts 

 of the conglomerate and granite occur at the 

 railway station. 

 65.5 m. About one and one-half miles north of 



105.3 km. Doherty fine-grained hornblende schists of the 

 Keewatin series are well exposed. These are 

 cut by light-grey dikes of quartz or granite- 

 porphyry. On the east side of the track the 

 conglomerate of the Cobalt series rests on the 

 upturned edges of the hornblende schists. 

 66. m. One-half mile farther north, outcrops of 



106. 1 km. Nipissing diabase occur. This rock is widely 

 distributed in Northern Ontario, and is of im- 

 portance because of the fact that it is closely 

 connected, genetically, with the phenomenally 

 rich silver-cobalt veins which occur near the 

 town of Cobalt, 36 miles (57.8 km.) to the north. 

 72. m. Between mileage 66 and Temagami, altitude. 



115.8km. 989 ft. (301.3 m.), good outcrops of Keewatin 

 schists and conglomerate of the Cobalt series are 

 seen. South of Temagami grey sericite schists 

 of the Keewatin series have resulted from the 

 metamorphism of quartz-porphyries. 



