TRANSACTIONS OF THE CANADIAN INSTITUTE. [Vou. VI. 
on 
(oa) 
The quantity of water in the lake will be increasing or diminishing 
according to the position of the outlet. If we draw a straight line 
through the outlet of each lake at right angles to the line of uplift, this 
isobase will represent the axes along which its surface is being tilted 
and on it there will be no change of level, while the further we go from 
it to the north the greater will be the fall and the further to the south, 
the greater the rise. This isobase of Lake Superior runs from Sault 
Ste. ,Marie to a point on the northwest side near the international 
boundary line. Heron Bay is the most northern and Duluth the most 
southern part of the lake in reference to this line. At.the above rate of 
tilting’ Professor Gilbert calculates that the fall in the lake at the former 
place is five inches and the rise at the latter six inches per century, or a 
Modern Raised Beaches, Pointe Bruté, North Shore. 
relative difference of nearly a foot per hundred years. This movement 
having been going on for a long time, the contrast in the appearance of 
the two sides of the lake is quite noticeable. On the north side, we see 
wide shores and many raised beaches, while on the south shore the lake 
is washing away the land or the waves are beating against the partly 
submerged cliffs and the coast has a generally drowned appearance. 
The contrast between these two conditions is well brought out by the 
accompanying illustrations, one showing modern raised beaches on the 
north side and the other the rising water eating away the sandstone on 
the opposite shore. — 
Before closing I may say a few words in regard to a possible cause of 
