174 The American Geolotjisf. March, 1895 
this discussion. It is possible, however, that it is the correl- 
ative of the Sault beach in the Superior basin and indicates 
a partial resubmergence, which may include the region of 
Sault Ste. Marie. 
This, then, is the history' of the second lake Algonquin and 
of the subsequent deformation of its ancient water plane, so 
far as relates to the area which was actually occupied b}" the 
lake itself. There are, however, other outlying regions, which 
were surely affected by the same deformations. Some of 
these are near and others that were less certainly involved are 
far away. But a full discussion of the evidences from such 
regions would lengthen this paper unduly. 
Ecidence of Recent Elecution (ind TilliiKj in Cont ignous 
Begions. Lake Erie, however, became so closely concerned 
with all the changes after the opening of the St. Clair outlet 
that it can hardly be omitted. It lies entirel}^ on the lower 
side of the node line AA, aiul all its shores were therefore 
drowned when the eastward component of deformatioii began 
to act; and they were affected to a less degree in the same 
way by the northward component also. The Nipissing plane 
produced southward under lake Erie would pass about 60 feet 
beneath the present level at the mouth of the Detroit river 
and about 80 feet below Sandusky and Toledo on the south 
shore. But it may be that the plane decreases its declivity 
gradually southward and does not pass so deeply under as these 
figures suggest. All the rivers of lake Erie, including even 
the muddy, silt-bearing Maumee, are without deltas, and have 
open estuaries, many of which are navigable. It is undoubt- 
edly the recent drowning of its shores that has made these 
harbors. Before that change took place, the Maumee must 
have had a fall of considerable bight ovei- the rock ledges 
above Maumee City. The recent backing up of the water is 
plainly shown by many spits and bars, like the points of 
Maumee bay, Sandusky and Erie, and those at Pointe Pelee, 
Rondeau and Long point on the Canadian shore. Upwards 
of a thousand square miles of the former lower valley of the 
Maumee were submerged by the eastward uplift. 
The deepest place in lake St. Clair is 80 to ;}5 feet at the 
extreme lower end of the lake, almost within the head of the 
Detroit river. The mean depth of the St. Clair river is about 
