166 
The Ainericau Geologist. 
Miirch, 1S95 
that lake had l)ecoiii(' independent ; 
that is, after the water luid fallen 
from the Nipissing to, or a little ^ 
below, the present Superior level at 
Sault Ste. Marie. For if that were 
the case, there would be a sharply 
accentuated beach passing west- 
ward from Sault Ste. Marie and 
sloping downward in that direc- 
tion under the lake so as to pass 
about 25 feet below it at the Pic- 
tured rocks and Presque Isle, and 
the cutting of that shore would ac- 
count for the present partly sub- 
merged cliifs. This probable sig- 
nificance of the cliifs of the south 
shore was long ago recognized by 
f)thers. There are so many features 
of this kind on the south shore and 
about the western end of the lake, 
all pointing to a recent stage of the 
lake at a lower level, that the exist- 
ence of this submerged beach seems 
certain. I propose to call it the 
Sault beach, for its place was de- 
termined by the barrier at Sault 
Ste. Marie. It was the last beach 
made by lake Superior before the 
beginning of the great eastward 
uplift and ought to appear above 
present lake level on all the Su- 
perior shore north of the isobase 
DD. The overhanging rocks, cliffs 
and caves of the Apostle islands 
show extreme littoral erosion, and 
this may be attributed to the fact 
that the present wave line strikes 
there a little above the same level 
that was so heavily cut by the 
waves of lake Algonquin. The 
•es ^ <a ^3 
' v-J 
