PRE-CAM BRIAN OF NORTHERN ONTARIO AND QUEBEC 325 



feet of interbedded argillite and impure sandstone, over which again 

 lies some 250 feet of conglomerate with some interbedded impure 

 quartzite. 



The writer's attention has been called by Mr. M. E. Wilson 

 to a peculiarity of some of the sheared conglomerates of the Larder 

 Lake district, which here and there are found to contain squeezed, 

 pebble-like masses distinguished by the presence of chrome-mica 

 or fuchsite. Fuchsite is also characteristic of the altered and 

 sheared porphyry masses of the region, and Wilson is inclined to 

 believe that unconformity is thus indicated between the porphyry 

 and the conglomerates. This, however, is obviously impossible, 

 since, as already shown (p. 317), the porphyries cut the conglomerate 

 and the other members of the sedimentary series. The writer 

 made a careful examination of the composition of the conglomerate 

 wherever it was found unsheared or only slightly sheared, but 

 found no pebbles containing fuchsite. It seems indubitable there- 

 fore that the fuchsite in the pebbles of the sheared conglomerate 

 must be formed during the shearing of the conglomerate after its 

 deposition. Fuchsite is not alone characteristic of the sheared 

 carbonated porphyry of the Larder Lake district, but it has been 

 found by the writer in several places in Keewatin rhyolites and 

 rhyolite tuffs which have been subjected to carbonate alteration 

 and subsequent shearing. Pebbles of the Larder Lake porphyry 

 are not found in the Timiskaming conglomerate here, but pebbles 

 of rhyolites in all stages of alteration are common. It is likely 

 therefore that some of these have given rise to the fuchsite pebbles 

 in the mashed types of conglomerate. 



The sediments were not traced farther to the east, as the next 

 2 miles is heavily drift-covered, and beyond this again the Cobalt 

 series overlies. To the east in Quebec the rocks are described by 

 J. A. Bancroft as follows: 



Exposures of a much metamorphosed conglomerate, arkose and grey^vacke 

 appear at intervals on both sides of the (Kinojevis) river for about three-fourths 

 of a mile. Either vertical or dipping very steeply to the north, and striking 

 nearly east and west, these rocks may be traced to Keekeek lake and the 



upper portion of the river bearing the same name (about 16 miles) The 



conglomerate is chiefly composed of pebbles of Keewatin greenstone, although 

 pebbles of granite and diorite are of frequent occurrence. Originally the 



