7 aS oe ¢ = 
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Ne a é. * 
100° — ‘Erratic Phenomena about Like Superior. 
gradually along the water courses, otherwise resembling’i in "(hie 
* composition the lake terraces; ‘which are altogether composed of — 
remodeled glacial drift, which, from the influence of the water ae 
~ and their having been rolled on the shores, have lost, more or 
. 
less, their scratches and polished appearance, and have assumed: ; 
the dead smoothness of water pebbles. Such terraces occur fre- 
quently between the islands, or cover low necks connecting prom- 
. Ontories with the main land, thus showing, on a small scale, how 
y the accumulation of loose materials, isolated islands may be 
combined to form larger ones, and how, in the course of time, by . 
the same process, islands may be connected with the main land. © 
The lake shores present another series of interesting phenom- 
especially near the gnouth of larger rivers emptying into the 
sa. lake over , where parallel walls of loose materials, driven by 
“the ® Jake &gainst the mouth of the river, have suc- 
d its course a caused it to wind its way between 
the actio 
cessively s 
.. the repeated accumulations of such obstacles. 
The lower course of Michipicotin River is for several miles 
dammed up in that way byconcentric walls, across which the 
river has cut its bed, and wintling between them, has repeatedly 
changed its direction, breaking “through the successive walls in 
different places. The lar argest and lowest of these walls, a kind 
of river terrace near the margin of the lake, shuts at present the 
factory from the immediate lake shore, and the river, which has: 
cut its way between the rocks to the right and the walls, has left 
a bold bank in this dam on its left shore. 
An important question now arises, after considering these facts, 
how these successive changes in the relative level of the lake and 
its shores have been introduced. Has the water been gradually 
subsiding, or has the shore been repeatedly lifted up? Merely 
from the general inferences of the more extensive phenomena 
described above, respecting the relative changes between land 
and sea, I should be inclined to admit that the land has risen, 
rather than to suppose that the waters have gradually flowed out. 
But there are about the lake itself sufficient proofs, which leave 
in my mind not the slightest doubt that it is the land which has 
changed its level, and not the Jake which has subside 
In the first place, to suppose that the lake had once s stood as 
high as the highest terraces, it would be necessary to admit that 
its banks were, all round its shores, sufficiently high to keep the 
water at that highest level, or, at least, that there were, at the 
lower outlets, bars to that height, which have been gradually re- 
moved since. But neither is “the main land sufficiently high, at 
the western extremity and along the southern shores, to admit of 
such a supposition, nor is there about the outlet of the lake, be- 
tween Gros Cap and Cap Iroquois, an indication of a barr) 
which has been gradually removed. Bhar as every where i eos 
