326 H. C. COOKE 



pebbles were well rounded and varied in size up to a foot across; they have 



been so flattened by pressure that today they possess lenticular forms 



The matrix of the conglomerate as well as the arkose and greywacke have been 

 quite universally converted into biotite schists, partially or completely 



recrystallized,yetrepeatedly exhibiting their originally clastic character 



That the sediments rest unconformably upon the Keewatin is evidenced by 

 the pebbles in the conglomerate and the position which some of the exposures 

 bear to those of the Keewatin. 



M. E. Wilson described the sediments thus: 



The Pontiac series in the district north of Kekoko and Kinojevis 

 lakes is composed of greywacke, arkose, and conglomerate, which extends in 



an east-west belt having a width of about 2 miles These rocks are all 



greenish gray or gray in colour, and have all been more or less mashed. The 

 greywacke is everywhere recognized by the quartz grains which it contains. 

 .... The arkose is of local extent and differs only from the greywacke in 

 containing more fragments of acidic minerals. The conglomerate consist of 

 mashed pebbles and boulders of granite, rhyolite, and quartz porphyry in 

 greywacke matrix. No pebbles or boulders of basic rocks were seen. 



Wilson also indicates on his map that the dips vary from 50 degrees 

 north to vertical. 



NEMENJISH SERIES ( ?) 



In the writer's last paper on this subject^ there were indicated 

 some reasons for beheving that a part of the body of sediments 

 mapped as Pontiac series might in reality belong to an older 

 sedimentary series which there were some reasons for believing to 

 be of Grenville age. Briefly stated, these reasons were the absence 

 of basal conglomerate at the east end of the sedimentary band and 

 elsewhere, the occurrence of amphiboHtes in the Pontiac series, 

 while amphibolites are not elsewhere found in the Mattagami (or 

 Timiskaming) series, but are common in the Grenville and its 

 supposed equivalents; and the occurrence of undoubted Grenville 

 within 30 miles to the south and to the east. The facts described 

 in this paper yield additional evidence on this point. The 

 Timiskaming of Ontario is pretty uniformly about 3,600 feet in 

 thickness through a band over 30 miles in length. As Figure 3 

 shows, in Quebec, 15 miles to the east, the band widens sharply 

 to more than 10 miles, throughout which the dips average 45 



^ Jour. Geol., Vol. XXVII (1919), p. 201. 



