58 



J. W. SPENCER 



Ontario and Georgian Bay, The postglacial bulge is like a sheet 

 raised by an object thrust under it, the height increasing from out- 

 ward from the focus of rise, but we can differentiate it in triangles 



Fig. i 



and obtain the mean rate for each. These should cover the sur- 

 veyed region, and be as nearly equilateral or right-angular as 

 possible. Thus the following results have been obtained. 



The mean rate of rise from the lowest points in the triangles 

 and the direction, based upon the height of the Iroquois beach, 

 cover the region of Lake Ontario. 



