246 
IOWA ACADEMY OF SCIENCE 
loess is found in such abundance, even in the territory contiguous 
to the Missouri River, at points remote from the river, occupying, 
for example, the great divide in Carroll County, Iowa, and a large 
part of the territory between the Platte and Elkhorn rivers in 
Nebraska, in many of these cases at the highest points in the ter- 
ritory, and the formation of these deposits in water would call for 
the flooding of enormous areas. No evidence of such flooding has 
yet been presented, though the presence of the loess has sometimes 
been accepted as such evidence. Moreover the presence of the 
great bodies of water postulated by this view would make impos- 
sible such accumulation of land-shells in their silt deposits as we 
find in the loess. 
Perhaps no argument has been more tenaciously adhered to by 
recent advocates of the glacio-fluviatile hypothesis than that based 
on the blending or intermingling of drift and loess, which has been 
urged as proof of the continuity or identity of the glacial and loess 
periods. Professor Todd offers nothing new on this phase of the 
question, though he derives much satisfaction from the assumption 
that it is true. In support of his view he cites Winchell for Minne- 
sota, McGee for northeastern Iowa and Udden for southwestern 
Iowa. Winchell’s references are usually so general that the writer 
confesses that he has not always been able to follow them in the 
field. He has, however, examined numerous loess and drift sections 
in southern Minnesota, and has uniformly found them like those of 
northern Iowa, without unique features. He is, also, familiar with 
the territory covered by McGee and Udden and has examined most 
of the section which they mention, and many others like them. 
Two types of this intergradation may be observed in Iowa and 
adjacent territory. The one is that between the fine sands and 
the overlying loess which may frequently be observed along the 
border of the Iowan drift in Iowa, as north of North Liberty; on 
the east side of the Missouri river, as at St. Jospeh, Mo. ; on the 
east side of the Mississippi river, as at Gladstone, 111. (see Plate 
III, fig. 1) ; and in the vicinity of West Point, Neb. In all these 
cases the areas in which such intergradation occurs show evidences 
of having been sand dune areas, or they are directly connected with 
existing sand dune areas. The intergradation is such as would be 
produced by the gradual fixing of the dunes by vegetation, and 
the subsequent deposition of fine materials by wind in the anchor- 
age thus provided. Illustrations of such transformations may be 
observed on a small scale in modern sand dune areas, as west of 
