vo. Thened 
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120 ILLINOIS ACADEMY OF SCIENCB 
sand. It seems most probable that this sandy soil was depos- 
ited simultaneously with or immediately following upon the 
formation of the kame-like ridge upon which it rests, and that 
it is due to similar combined action of ice and water. The exact 
method of its deposition may be more definitely explained upon 
further investigation, the main point of interest at the present 
time, however, is that the sandy mounds which cap the ridge 
are not composed of lacustrine sand piled up by the wind, but 
have an origin connected more immediately with the former 
ice sheet. It is evident that this material being largely sand 
and lying in an exposed situation has been subject to disturb- 
ance and working over by the wind. Dunes have been and are 
being formed from it and these dunes may be termed terrestrial 
in origin. 
If it be granted, as the evidence seems to demand, that these 
perched dunes of Fox Island are terrestrial, it seems highly 
probable that many of those of the Sleeping Bear area had a 
similar origin, for the topography of the two regions is so 
extremely similar. The large mass of material in the advancing 
dune swept from the plateau upon which the Sleeping Bear 
dune rests would present no difficulty when explained by the 
hypothesis of terrestrial origin. 
Without extensive investigation it is impossible to say just 
how many of the sand hills upon South Fox Island are dunes 
and how many are made up of glacial sands. It is certain that 
the high bald dune in the center of the island is composed of 
wind-blown material and is still slowly moving across the 
island, but it seems highly probable that many of the peaks 
which immediately surmount the shore cliff were, in their 
deposition, intimately related to some phase of glacial activity. 
The hills at the east of the shore ridge probably are in part 
dunes, and in part glacial sand hills, the two showing no differ- 
ence in plant covering. 
The variations in the plant associations of the various dune 
regions mentioned will be discussed elsewhere but it seems 
worth while to call attention to the climax mesophytic forest 
as developed upon the sand hills of South Fox Island. Although 
less than 25 miles from the mainland, where these species 
