26 Bulletin Wisconsin Natural History Society [Vol. 12, Nos. 1 & 2 
which would have consisted of sedges and ecologically allied 
plantsd® The structure of the hill as revealed in two road cuts 
and a sand spit indicate that it was formed through glacio-fluvial 
deposition; its composition, being largely of yellowish sand mixed 
in places with a very small amount of fine gravel showing indis- 
tinct laminations, leads one to this belief. Towards the crest of the 
hill and in irregular patches along the hillside the sand is finer, 
is not mixed with gravel, and in places shows distinct laminations 
which are sometimes intermixed with narrow layers of humus. 
We would conclude from this, as Shimek has concluded in regard 
to a similar structure in the Iowan drift, that this area in its early 
history was a sand dune formation. Shimek writes: “The struc- 
ture of these underlying sands suggests that soon after the reces- 
sion of the Iowan ice there were extensive sand-dunes formed 
along the borders of the Iowan drift, and that there were isolated 
dune areas within the Iowan border. These shifting sands were 
probably bare for a time and the winds easily removed the finer 
particles of dust in great quantities. The successive changes were 
probably such as take place in recent times in any sand-dune 
region. At first a scant vegetation consisting, perhaps, of tufted 
sedges and grasses and leguminous plants, is developed. Each 
plant forms a nucleus about which a small amount of finer soil 
material is gathered. While each plant thus serves as an anchor- 
age for fine material, there are at first comparatively broad areas 
of loose shifting sands between these plant-tufts. As the scant 
vegetation gathers the finer soil, it prepares the way for a denser 
vegetation, which will accumulate more fine soil to the advantage 
of still other plants, until the whole area is covered with a carpet 
of plants which will check if it does not wholly prevent wind 
erosion. In the Iowan sand-dune area the fine material thus 
blo\vn out of the sands was, after the recession of the Iowan ice, 
carried to the above noted elevations, and there lodged. It should 
be borne in mind that these elevations presented the first suitable 
surfaces for terrestrial plants, for, no doubt, for a long period the 
flatter areas were at least swampy, resembling probably the cor- 
responding areas upon the Wisconsin drift plain. Other portions 
were, evidently, for a time shifting sands upon which vegetation 
Any statements as to the chronological order of ingression of the older Inota or as to en- 
vironmental conditions at that time must of necessity be considered more or less hypothetical. 
