PLEISTOCENE DEPOSITS BETWEEN MANILLA IN 
CRAWFORD COUNTY AND COON RAPIDS IN 
CARROLL COUNTY, IOWA. 
ABSTRACT. 
GEORGE F. KAY. 
The most significant features that have been revealed by a 
study of the Pleistocene deposits in many deep cuts made recently 
between Manilla in Crawford county and Coon Rapids in Carroll 
county, by the Chicago, Milwaukee and St Paul Railway Com- 
pany, may be summarized as follows : 
1. The chief kinds of material exposed are loess, Kansan 
gumbotil, Kansan drift, Nebraskan gumbotil, and Nebraskan 
drift. In no one cut is it possible to see all of these materials, nor 
are the two gumbotils exposed in a single cut. In some cuts the 
section shows loess, Kansan gumbotil, and Kansan drift; in other 
cuts there may be seen loess, Kansan drift, and Nebraskan gum- 
botil ; in still others loess, Nebraskan gumbotil, and Nebraskan 
drift. The most comprehensive cut is about one and one-half 
miles west of Manning. It shows loess, Kansan drift, Nebraskan 
gumbotil, and Nebraskan drift. 
2. The two drifts, the Nebraskan and the Kansan, are much 
alike lithologically, and both appear to have undergone similar 
changes. On each of the drifts, gumbotil has been developed, be- 
low which there is a narrow zone of leached drift, which grades 
downward into unlea-ched drift with many concretions. 
3. The maximum thickness of the Nebraskan gumbotil is about 
thirteen feet, and of the Kansan gumbotil more than twenty feet. 
The zone of oxidation of the Nebraskan drift is not fully exposed 
in any of the cuts; the greatest depth of oxidation seen was 
seventeen feet. The zone of oxidation of the Kansan drift has a 
maximum depth of about forty feet. Beneath this oxidized zone, 
in a few cuts, there was seen less than ten feet of very dark, 
tenacious, unleached and unoxidized Kansan drift. 
4. The Kansan gumbotil is limited in distribution to a few 
narrow divides which are erosion remnants of a former, exten- 
sive, Kansan gumbotil plain. These divides are the present up- 
