NOTES ON THE NEBRASKAN DRIFT OF THE LITTLE SIOUX 
VALLEY IN CHEROKEE COUNTY. 1 
BY J. ERNEST CARMAN. 
The work of Professor Shimek, of the Iowa Geological Survey, in 
western Iowa, has brought to light many exposures of Aftonian gravels 
and the underlying Nebraskan (pre-Kansan) drift. These exposures ex- 
tend along practically the entire western border of Iowa. 
While engaged in a study of the Pleistocene deposits of northwestern 
Iowa for the Iowa Geological Survey during the summers of 1910-1911 
the writer observed a number of exposures of Nebraskan till along the 
Little Sioux valley in Cherokee county, and it is the purpose of this 
paper to call attention to this extention of the known distribution of 
the Nebraskan. The head waters of the Little Sioux river are within 
the area of the Wisconsin drift, but most of its course is through the 
region of the Kansan drift 13 - and through a part of this Kanasn area the 
river has cut down 1 below the base of the Kansan, and flows at the level 
of the Nebraskan. The valley-bed is covered with alluvium and glacial 
gravels so that exposures of the Nebraskan are relatively few, although 
the actual area over which this drift occurs below the alluvium and 
gravels, may be considerable. The exposures of Nebraskan are found 
only in the valley bottom or in the lower part of the bluffs, at no place 
rising more than half way to the level of the upland. 
Most of the Nebraskan exposures observed occur in Cherokee county 
in the valley of the Little Sioux north and south of Cherokee, and in the 
valley of Mill creek north of Cherokee (Fig. 1). Exposures were ob- 
served, however, as far up the river as Peterson in southwestern Clay 
county, and as far down the river as Anthon in Woodbury county. The 
total number of Nebraskan exposures recorded on the field maps of the 
writer between these two places is more than fifty. 
At several places north of Cherokee the Nebraskan drift rises in the 
bluffs to an elevation of 50 to 60 feet and at one place to 80 feet above 
the river, while the length of individual exposures may reach 75 to 100 
Published by permission of the Director of the Iowa Geological Survey. 
la Part of the area here referred to the Kansan may belong to a post-Kansan, pre- 
Wisconsin drift sheet. 
