Fi, Desor on the Drift of Lake Superior. 105 
bars, or banks, under water, rather than on the border of the 
coast, siuce we know that such ridges are forming in our day in 
shallow water both in the sea and large lakes. It ought to be 
remembered that the summit of these submarine ridges is not 
always even, nor their bearing necessarily horizontal; so that a 
slight inequality in their outlines, especially if limited to a nar- 
tow space, does no more imply a local change of level than in 
the case of the terraces before mentioned. Since, from the na- 
ture of things, raised beaches and esars are expected to occur in 
the same localities, it must be left to the sagacity of the observer 
.to determine in each case to which class they belong. Instances 
of both have been noticed, at numerous points, along the shores 
of the lower lakes, but they are less frequent on the coast of 
Lake Superior, although not entirely wanting. 
Flat characterized by those peculiar markings which we have 
tween he 
tetion 
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