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down when the surface rocks were largely volcanics, and 

 that the intrusion of at least part of the granite came after 

 the deposition of the Temiskaming, but prior to the Cobalt 

 series. 



At the North Dome there is a strikingly banded rock 

 which was originally a succession of fine clay and rather 

 coarse sand layers. A secondary cleavage is developed at 

 a low angle with the upturned edges of the strata. 



On the Foley-O'Brian the sediments in addition to being 

 highly tilted show a wavy structure along the strike. 



At the Dome property, in contact with large quartz 

 masses, is a conglomerate which is likely basal. On the 

 weathered surface the included fragments of porphyry, 

 greenstone, schist, etc., are conspicuous, but in freshly 

 broken pieces the conglomeratic character is easily over- 

 looked, since the rock breaks in prismatic blocks resembling 

 schist. The included pebbles are frequently drawn out in 

 the direction of the schistosity. 



The Cobalt Series. 



The younger series of pre-Cambrian sediments has been 

 observed only in small volume on the south boundary of 

 Langmuir township, about 15 miles to the southeast of 

 Porcupine lake. 



Later Intrusives. 



In all parts of the area are basic dikes which generally 

 are less than 100 feet in width. These dikes appear to here 

 represent the Nipissing diabase of Cobalt and the later in- 

 trusives of that area. At Porcupine they are believed to be 

 much younger than the gold deposits. 



