48 
IOWA ACADEMY OF SCIENCE Voi.. XXVIII, 1921 
weathered but some of them are crumbling from decay. The clay 
is dark blue when moist, a bluish gray when dry and is non-calcare- 
ous throughout. In this deposit on the east side of the pit, a glob- 
ular pocket of fine sand was found. It is about four feet in diam- 
eter. Specimens of each of these materials were obtained for the 
college museum. 
The irregular upper surface of this till, shown in the diagram, 
indicates a much eroded area in this vicinity at the time the Kan- 
san glacier advanced over it. This till is believed to be the Sub- 
Aftonian or Nebraskan and is identical in appearance and de- 
scription with one that has a much more even surface where it has 
recently been exposed in several other deep excavations made in 
this vicinity. 
In a generalized section for this area, there are about eighty 
feet of Wisconsin till, five feet of loess, twenty feet of Kansan 
till above the Nebraskan till of which ten to fifteen feet are ex- 
posed. 
State College, Ames. 
