110 J.B.TYRRELL — POST-TERTIARY DEPOSITS OF MANITOBA. 



Mr. Tyrrell: I may say ;i word with regard to the bowlders referred to 

 by Professor Spencer as scattered over the Biirface in the Northwest. It is 

 being recognized by a number of explorers that there is probably Borne little 

 difference in origin between the bowlders lying on the Burface and those in the 

 underlying bowlder clay. In many cases it is impossible that the bowlders 

 could have been derived by denudation from the bowlder clay beneath ; and 

 I am rather inclined to suggest the explanation thai those bowlders were 

 transported in the mass of the glacier itself instead of having been beneath 

 it. as was the till, ami that as the glacier melted and retired they were dropped 

 nil the surface. I think that this explanation will fairly account for the 

 presence "t* most of the solitary local bowlders on the surface of the plains, 

 where they cannot be accounted for by erosion. 



