THE PRE-CAMBRIAN OF WESTERN PATRICIA 



395 



logical resemblance, and because it is the oldest rock-formation 

 present and antedates all of the granites with which it is in contact. 

 Tentatively, however, the local name "Lac Seul Series" may be 

 applied to it. 



2. The series above the volcanics appears to be of predomi- 

 nantly sedimentary origin, with a basal conglomerate which has a 



Fig. I. — Map indicating pre-Cambrian areas mentioned in this paper 



rather wide extent. It was observed especially at Slate and Birch 

 lakes and was also reported by Dowling at Red Lake. In all three 

 localities it is of practically identical lithological composition. 

 Following Moore's example in the case of a similarly related series 

 in eastern Manitoba, it was assigned to the Lower Huronian.^ 



^ See Ont. Dept. Mines Report, 1920, p. 181, and compare Geol. Surv. Can. Sum- 

 mary Report, 1912, pp. 262 ff. 



