Abandoned Shore Lines of Lake Superior. — Taylor, :5s;} 
cidence of vertical interval, which is probably accidental, 
these two strands are not the same. 
The very exceptional strength of the Nipissing beach all 
along the south shore led me to hope that it might be identi- 
fied among the beaches described by Prof. Lawson. Its rise 
to the north, as indicated between Marquette or L'Anse and 
Eagle Harbor, is very slight, and unless thrown out of place 
b} r very recent deformation it would be expected at an alti- 
tude somewhere between 50 and 100 feet along the north shore. 
Well developed beaches within this limit are described by 
Prof. Lawson. By a careful comparison of his descriptions of 
the lower beaches I think the Nipissing beach may be fol- 
lowed with tolerable certainty as far as Pie island, south of 
Port Arthur, where there is a beach like it at an altitude of 
43.5 feet, but beyond that its identity is very doubtful. At 
several places it was probably removed by a heavy wave-cut 
at a lower level. 
We shall not know the complete history of lake Superior in 
the great submergence until the highest shore line on the 
north coast has been definitely located at a number of points, 
and this will probably require a laborious investigation di- 
rected particularly to that end. When this is done it will 
probably disclose the existence of straits of considerable mag- 
nitude connecting the Superior basin with that of Hudson 
bay across the Hight of Land. One of these straits probably 
passes northeast over Missinaibi lake, and another north over 
lake Kenogami ; and there may be others across the watershed 
north of lake Nipigon. The discovery of a great strait over 
lake Nipissing, and the probable existence of another over 
lake Tamagaming, northeast of Lake Huron, add much 
strength to this supposition. There is proof enough that the 
highest beach from Duluth to North Bay is a unit, and thai 
makes the several straits referred to all arms of one body. It 
would require several ice dams at widely separated places to 
hold this vast body of water up. If the existence of strait- 
northward from lake Superior is established, it will settle the 
case for the upper lakes in favor of open marine connection 
as against ice dams. 
