1882 .] 
368 
[Davis. 
extremity of Ontario by a well-proven channel passing Cayuga 
and Seneca 1 ; the Georgian Bay perhaps draining through Lakes 
Simcoe and Balsam and the River Trent into Ontario ; and the 
united waters leaving Ontario near Oswego, passing Onondaga 
Lake, and perhaps following a deep channel under the Mohawk into 
the Hudson and down to the Atlantic by New York, though the 
possibility of this is questioned. Farther west, Superior drained 
into Green Bay, and perhaps on by the Rock River into the Mis- 
sissippi ; Michigan flowed out at Chicago, south and southwest, 
but its connection to the Ohio or Mississippi has not been traced . 2 
During this condition of river drainage the lakes did not exist ; 
their troughs were empty excepting along the deepest bottom 
line, with the probable exception of the orographic Lake Superior. 
To this it may be objected that the bottom of the more north- 
ern basins is below the supposed southern outlets; but the difficulty 
is fairly overcome by considering this reversed slope the result of 
northern subsidence which followed the glacial period : this sub- 
sidence is well proven for the Atlantic coast, and is very probable 
for the interior as well : this would place the basins in part under 
the warped valley species. There is additional and independent 
evidence of the former emptiness of the lake-troughs; first, in 
the true fjord-character of the shores of the Georgian Bay and 
other northern waters, the result of erosion at a time of 
drainage below the present water levels; the occurrence of these 
fjords on the northern shores points to their having formerly 
stood higher and later having been more depressed and over- 
flowed than the southern; second, in the deeply buried channels 
of many streams or rivers running into Erie and Ontario (and 
probably the other lakes as well), whose rock bottom is about 
as low as the bottom of the lake-trough itself . 3 The position 
of these troughs was determined by that of the more easily 
1 These towns on the Grand River of Canada West are not to be confused with the 
lakes of the same name in New York. 
2 These buried preglacial channels must not be confounded with the southern lines 
of overflow or “ waste weirs” that were used during the glacial period, when the lake 
surfaces stood higher than now by two or three hundred feet. 
3 The lakes of Central New York are to be considered as occupying such old 
deep valleys. 
