226 
IOWA ACADEMY OF SCIENCE 
the bowlders and pebbles in question being the droppings from the ice- 
bergs that during many ages broke from the edge of the ice-sheet and 
floated out upon the waters that then covered Iowa. It is hardly neces- 
sary to call attention to the fact that the hypothetical sea was immediate- 
ly post-Kansan, while the so-called loess was deposited subsequent to the 
erosion of the Kansan. The stratified silts, clays, and limes, that should 
have 'been deposited in such a sea, all are lacking, and of the morainic 
rampart hundreds and hundreds of feet in height necessary to dam 
back so vast a mass of water no trace remains, heaving out of the ques- 
tion all such grotesque theories, let us inquire as to the possible explana- 
tion of the occurrence of the so-called loess, supposing it to be what at 
first glance it would appear to be, namely an aeolian deposit. 
THEORIES AS TO THE ORIGIN OF THE SO-CALLED LOESS, 
1. Finding this material near the edge of the Wisconsin lobe, which 
passes through Guthrie County, one might at first conclude that this is 
a phase of the Wisconsin loess. The fact that it is, structurally, not 
loess has been sufficiently dwelt on. The theory that would relate it to 
the Wisconsin is untenable, since it passes under the Wisconsin drift 
sheet in Guthrie county. It may therefore be laid down as a fact that 
it is older than the Wisconsin drift. 
2. It has been suggested that this is an aeolian deposit whose materials 
were gathered from the outwash of the Iowan glacier, and it has ac- 
cordingly been described as 4 4 Iowan loess,” The true Iowan loess ap- 
pears in abundance in Linn and Johnson counties. It is extremely fine- 
grained and easily carried by the wind. The Adair County material 
is coarsely granular, heavy, and is not readily moved by air currents. 
The adherents of the Iowan loess theory would have us believe that the 
finer materials were deposited near their source, while the coarser and 
heavier matter was caught up and blown half way across Iowa and 
there deposited in great quantities. The writer cannot yet accept this 
contradition of the principle of gravitation. On the face of it the 
theory is untenable. 
3. The same objection prevents us from accepting the theory as to 
the source of this material being the valley of the Missouri river. The 
Missouri loess is fine-grained, easily blown, and travels far, but is not 
found in Adair County. This so-called 4 4 loess” is. heavy and coarse, 
and does not travel readily. If the Missouri loess cannot travel a!s far 
as Adair County in appreciable quantity, this heavy material certainly 
could not. 
