254 Canadian Record of Science. 
Let us examine each lake in turn. 
LAKE SUPERIOR, 
This lake is so distinct from the other lakes in its origin, 
that it must be separately considered. 
The point of greatest depth is not in the centre, but forty 
miles north-east of Duluth, and about six miles off the west 
shore, where, in a small area, 1,026 feet is reached, or 426 
feet below ocean level. The depression to this low level at 
this point is, as frequently occurs elsewhere, very sudden, 
the depths at the immediate sides being 690 and 816 feet. 
The line of deepest depression at this end of the lake does 
not lie along or near the central line ofthe lake, but follows 
somewhat irregularly the west shore from near Duluth 
until it reaches the entrance to Thunder Bay. Between _ 
this bay and Isle Royale the maximum depth is 990 feet. 
From that part of this line of deepest depression, lying 
south-west of Isle Royale, the lake bottom shallows, at first 
somewhat gradually, but finally more rapidly to the south 
shore east and west of the Apostle Islands. 
Along the west shore of the lake the coast line is often 
high, being in frequent places from 900 to 1100 feet, and at 
Thunder Cape attaining over 1300 feet. Below the water- 
line, for nearly the whole distance between Thunder Bay 
and Duluth, there is at or within a mile of the shore a sud- 
den descent to depths varying from 100 feet in some locali- 
ties to over 600 feet in others, whilst in one instance along- 
side the islands, off the east side of Thunder Cape, the 
bottom is only reached at 780 feet. Two miles further 
away from this general coast line the depth becomes 500 to 
1000 feet. Thus along this west coast shore, from the sum- 
mit of the heights overlooking the lake to the deeper points 
in the line of the depression, which is generally about five 
miles distant, there is a total descent varying from 1600 to 
1900 feet, except at Thunder Cape, where it is increased to 
2140 feet. These soundings suggest that between Black 
Bay and the westerly end of the lake there are, running 
