E. Desor on the Drift of Lake Superior. 99 
I noticed was one of hornblende, near Carp river, measuring 
fifleen feet in length, eleven in width, and six an 
height; another, near the Portage, measured eight and a half feet 
in length and five in width. On the borders of Lake Superior, 
as in all other countries where drift occurs, the boulders are the 
most widely diffused. They are scattered over the whole coun- 
try, and may be seen at all heights, where no other drift deposits 
reach. They are truly the vanguard of the drift formation, in 
height as well as in space. Even the dividing ridge, where it 
rises the highest, does not limit their extent; for they have been 
found as high as. one thousand feet above the lake south of the 
Anse, and may from thence be traced uninterruptedly along the 
southern slope of the ridge into the prairies of Wisconsin and 
Illinois. As to their mineralogical composition, there is every 
Vanety of rocks to be found, and in many instances they may be 
traced to their origin at no very great distance. We thus soon 
accustom ourselves not to look any longer upon them as strangers, 
as we do where there is no analogy whatever between them and 
the rocks on which they rest. Among the most numerous boul- 
ders along the lake may be mentioned those of granite, trap, and 
hornblende rocks, which are common to both shores. Bonlders 
Sandstone are less frequent, in spite of the great predominance 
of this rock along the south shore—a circumstance easily ac- 
counted for by its greater softness, which renders it the more de- 
Structible, Asa general rule, it may be stated that most of the 
boulders scattered over the Lake Superior region have not come 
fom far. This is of the utmost importance, since it actually 
enables us to trace the route which they have followed; and as 
to their direction, 1 feel no hesitation in affirming that most of 
the boulders within the region of Lake Superior have been trans- 
@ from north to south. As instances of this southerly 
ation, I shall state the following facts. ‘The iron region 
Snags Superior is situated near Carp river, east of Keweenaw 
ian, aud, although the ridges where the iron ore occurs are 
Ysome ten miles from the shore, yet there is not a single 
This hor even pebble, of iron to be seen north of the ridges, 
the te, of which there are innumerable fragments scattered at 
~ 00t and in the immediate vicinity of the ridges, is So con- 
0 i the iron ridges towards the south, iron pebbles 
ee. Thus, j : iin Pasa 
Tidge 1s, in September last, Mr. Whitney, starting from 
. th io boulders of fee 
off; his route towards the Esconauhee river, some tw a 
a ( ill fa er. 3¢ veh sitaaee 
