370 The American Geologist. June, n-94 
deposit. It is hardly possible that so strong a feature as the 
Nipissing beach at Marquette and the Portage lake canal. 
implying so long a duration of wave action at one plane, 
should not be continuous westward along the same shore. But 
there is nothing above the level of the spits at Duluth which 
can be correlated with it, and the clay terrace at Superior, 
which is 20 to 40 feet above the lake, could not have withstood 
the action of the Nipissing waves. 
Sun// Ste. Marie mid eastward. The great strength of the 
development of this shore line, taken in connection with tin- 
fact that it is only a few feet above the present level of lake 
Superior, led me for a considerable time to call it the Sault 
Ste. Marie beach. But by subsequent exploration at Sault 
Ste. Marie and at other points east of there, and especially at 
lake Nipissing (an account of which has been given in a pre- 
ceding paper*), I was forced to conclude that this shore line 
marks the level of the Great Lakes during the active period 
of the Nipissing outlet river, anil not a higher stage of lake 
Superior alone. Before visiting Sault Ste. Marie it seemed 
probable that this beach belonged only to lake Superior and 
that it began to be formed when that lake became an inde- 
pendent body of water. It Seemed probable that its level had 
been determined by a barrier at the Sault. But this is not 
the case, for at that place the same strong shore line passes 
through the valley of the Ste. Marie river and its altitude 
above lake Superior is about fifty feet. The' outlet of lake 
Superior at that time was not a river, but a narrow strait 
with a gentle current. There is no recent rock cut worth 
mentioning at the Sault. Probably part of the river channel 
below is of postglacial age, but the most of it is certainly pre- 
glacial. The sediments of postglacial submergence extend 
close up to the foot of the Sault, proving conclusively the very 
short time since the beginning of its present period of activ- 
ity. Professor Lawson gives the altitude of a shore line on 
the Canadian side, which I identified as the Nipissing beach, 
as forty-nine feet above lake Superior. It may be seen as a 
finely formed cut terrace, with a marked boulder pavement, 
along the foot of the hill below the new barracks back of the 
*"The Ancienl Strait at Nipissing", Bulletin <;. S. A.. Vol. v. 1894. 
Am. Geologist, vol. xin, p. 220. March, 1894. 
