E.. Desor on the Drift of Lake Superior. 93 
Arr. XI.—On the Drift of Lake Superior ; by E. Desor.* 
_ Tue region of the great lakes may be considered as the head- 
quarters of the North American drift. From the mouth of the 
Throughout this long line of inland country there 
is, however, no place where they are more extensive than on the 
southern shore of Lake Superior—more especially its southeast- 
em coast. There, they not only constitute the only visible for- 
mations for nearly one hundred miles, but they also attain an as- 
tonishing thickness, so as to form, by themselves, ridges and 
culls which exceed in height even those of the Pictured Rocks 
—being in some places (for example, at the Grand Sable) not 
less than three hundred and sixty feet high. In consequence of 
this preponderance of the drift deposit, that portion of the shore 
of the great lake is the least attractive in a picturesque point of 
vieW—it being in the nature of the detrital deposits to soften 
down the contrasts, and to produce uniformity and monotony. 
The drift is less conspicuous along the western portion of the 
lake shore, although it is not wanting even among the romantic 
and precipitous cliffs of the Pictured Rocks and the Red Castles. 
The drift of Lake Superior may be divided into four different 
deposits, which, in an ascending order, exhibit the following char- 
rive the whole region, forming the uppermost portion of the 
Grit deposits. The polis ed and grooved surfaces which occur 
connection with the drift constitute, likewise, a most impor 
on ture in its history. Finally, there are the drift terraces - 
to ascertain. thei saa i f level 
“wp: tain their bearing in reference to the changes 0 ave 
j Which have taken place during and since the drift epoch. doa 
“1 | ' } ; " . : % pis dle 
the aut Sue Report of Messrs, Foster an wie; roreed 
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