— 
Geology of Lake Superior. 29 
ses and altogether insignificant in their effects when compared 
with those terrific convulsions to which we have alluded, It 
will be perceived, that we make no mention of the few dilu. 
vial beds which are occasionally met wilh on Lake Superior. 
That subject has been noticed by Doctor Bigsby, and to him 
we refer our reader. That Gentleman has, however, made 
no mention of those alluvial operations, which have been for 
ages, and are still,at work. ‘These we are aware, are not ex- 
tensive ; yet this appears to us inferior in interest to no other 
branch of geological inquiry ; for here the cause is still in ac- 
tion, We have therefore certain data from which to draw our 
@eductions, which can never be the case, in regard to phe- 
nomena of diluvian, much less of antediluvian origin. We 
however acknowledge that the circumstantial evidence at- 
tending many diluvial depositions, falls little short of posi. 
tive proof. 
24. At the bottom or southern side of that bay, of which 
Point Iroquois is the east point, sandstone, horizontally stra- 
tified, is succeeded by sand and gravel, which runs up to the 
northward 17 or 18 miles, forming the projecting low head- 
land of White Fish Poiat. From this point, in a W. by S- 
direction 45 miles, the coast is composed exclusively of beach- 
es of fine sand and gravel, to the west point of the Grand 
Sable,* where the horizontal sandstone again makes its ap- 
pearance, protruding from under the sand. A line drawn 
from the first point in the bay to the westward of Point Iro- 
qnois, to the last—the west point of the Grand Sable—will cut 
off to the northward a triangular tract of country, which is 
composed of sandy barrens or downs. 
It is probable that the southern parts of this tract may be 
diluvial, like the Grand Sable, but the northern part, for a 
considerable distance in rear of the present margin of the 
lake, is composed of parrallel ridges of sand hills, which havg 
evidently 
* For the description of this immense diluvial bauk of sand ond 
gravel, see Schoolcraft’s tour, 
