322 H. C. COOKE 



deposits from torrential streams; and that the beds, if worked out 

 in detail, will be found to be lenticular in shape. 



The basal conglomerate near Kenogami station is composed 

 almost entirely of detritus from the underlying volcanic series. 

 In a railway cut here it is in contact with a serpen tinized agglom- 

 erate or flow breccia of very unusual composition and appearance. 

 The conglomerate contains numerous rounded pebbles of this 

 material, so that the fact of unconformity is indubitable. These 

 pebbles are also slightly schistose, although the conglomerate and all 

 the other pebbles are quite massive, so far as observed ; so that some 

 deformation must have preceded the deposition of the conglomerate. 



The conglomerate is crowded with pebbles, particularly near 

 the base where 75 to 80 per cent of the total mass is pebbles. They 

 vary in size up to a foot in diameter, but the majority are from 

 I to 4 inches in diameter. They are mostly pretty well rounded 

 and worn. About half of them are longer in one direction than 

 the other, presumably due to their original structure, and the long 

 axes commonly lie parallel to the plane of bedding in the con- 

 glomerate. All the pebbles appear to be massive, with the one 

 exception noted above. Approximately 50 per cent are of the 

 light-colored cherty tuff which commonly accompanies rhyolite 

 flows; some of these are probably also rhyolite. Thirty-five to 

 40 per cent are basalts and gabbros, the latter probably from the 

 coarser-grained parts of basalt flows. The remaining 10 to 15 

 per cent consist of red jasper, banded chert, porphyry, and the 

 peculiar breccia mentioned above, with here and there one of red- 

 dish granite and syenite. In the Upper parts of this bed there is a 

 somewhat greater variety among the pebbles. Quite a number 

 are to be found of a quartz porphyry common among Keewatin 

 rocks, and grayish granite pebbles are fairly common. 



The matrix of the conglomerate is a rather coarse grit, composed 

 of the small fragments of the rocks which supplied the pebbles. 



The conglomerate is massive and unsheared. The stresses 

 developed during the folding have been relieved, not by schisting, 

 but by jointing accompanied by a number of small faults. 



Many of the conglomerate beds lying at some distance above 

 the base of the series, as in the second locality mentioned above 



