292 The American Geologist. November, 1894 
be shown to have been the drift filling the old valleys and the 
warping of the earth's crust. But the basins are river-like 
ami broad submerged valleys. Lake Ontariois 247 feet above 
the sea, but its greatest depth is 738 feet; and throughout a 
considerable portion of it, the southern side is bounded by 
high vertical but submerged walls, which for long ages formed 
blufi's along the ancient river.* Besides the longitudinal 
trough, another deep channel crosses the basin east of Toronto. 
Lake Erie is 573 feet above tide, but it is generally less than 100 
feet deep, except over a small area where it is 210 feet; but 
beneath the waters of the shallow basin there are many buried 
channels, the deepest of which, at Cleveland, is 228 feet 
(Newberry). Lakes Michigan and Huron and Georgian bay, 
are at one altitude, 5S2 feet above the sea. Georgian bay is 
generally less than 200 feet deep, but at its southwestern side 
a channel reaches to a depth of 510 feet, in front of the foot 
of a very high escarpment, part of which is submerged. An- 
other submerged escarpment crosses lake Huron. This has a 
descent of more than 400 feet. The deepest sounding is 750 
feet. The two basins of lake Michigan (respectively 864 and 
576 feet deep) have vertical submerged escarpments adjacent 
to them. Also there are some deep channels and fjords, one 
of which is 612 feet deep. Lake Superior has been studied 
less. More or less drift is known to occur between the lake 
basins, like that filling the submerged channels under lake 
Erie. The buried valleys will explain the connection between 
the lakes. 
Jf. Glaciation of the Region. The stria 1 are nowdiere par- 
allel to the direction of the escarpments, whether these be 
submerged or above the level of the lakes, where they form 
bold topographic features. Nor are the vertical walls of the 
limestone escarpments polished by lateral glaciation. In 
short, the strhe are at considerable angles, even at right angles, 
to the rocky escarpments. Thus it appears that the valleys 
were not shaped by glacial action. 
*"Notes on the Origin and History of the Greal Lakes," by the writer, 
Proc. Am. Assoc. Ads-. Sci., vol. xxxvii, 1888, p. 197; "Origin of the 
Basinsof the Great Lakes of America," by the writer, Quajrt. Jour. Geol. 
Soc., London, vol XL VI, p. 523 (also in AMERICAS GEOLOGIST, vol. vii, 
pp. 86-97, with map of the ancient Laurentian river system, Feb., 1891); 
and earlier papers. 
