464 



REGINALD E. HO RE 



Where the contact of the conglomerate with underlying rocks has 

 been found there is a noteworthy lack of alteration in the older rocks. 

 If they were deeply disintegrated by surface weathering the material 

 must have been removed by a very efficient agent. This again sug- 

 gests ice action. In a few of the contacts the line of demarcation is 

 less distinct, as is ordinarily the case with unconformities in water- 

 laid sediments. Naturally the contacts of the latter type are not so 

 likely to be found as those of the former. 



Fig. 5. — Huronian conglomerate, Coniagas Mine, Cobalt, Ont. A horizontal 

 exposure. 



There has not yet been found a smooth or striated floor. The 

 basal conglomerate, in some cases at least, has been formed in situ 

 and is made up of detritus from the immediately adjacent rocks. 



Professor Coleman does not consider that the lack of discovery of a 

 characteristic glacial floor precludes the possibility of the material 

 having been placed by ice, and refers to well-known instances in 

 which such a floor is lacking. 



The localities specially mentioned by Dr. Coleman are Cobalt and 

 Temagami. Cobalt Lake, on which the town is situated, lies almost 

 entirely in Huronian conglomerate. The conglomerate in turn lies 

 in a deeper valley formed by rocks of the Keewatin group. It might 

 be expected therefore that the coarser material in the conglomerates 



