POST-KANSAN GLACIATION NEAR IOWA CITY 435 
the weathered and the unweathered portions. Such, however, does 
not occur. Besides the foregoing significant relations, the gravel 
is uniformly weathered at different depths, but the till is not. 
The conclusion is therefore clear that an ice-sheet, capable of 
distorting and molding this hill of material, invaded this region 
after the Buchanan gravel and some of the Kansan till were much 
weathered. 
In view of the above interpretation there are four important 
points embodied in this cut: (1) the Kansan drift and the Buchanan 
gravel record the invasion and retreat of the Kansan ice; (2) the 
weathering of the same represents a considerable time interval 
after the Kansan invasion; (3) the contacts record the close of 
that interval and the folds give identity to the presence of a later 
ice-sheet and its movement; (4) the yellow loess, at least in this 
exposure, was deposited subsequent to the advance and retreat of 
the later ice-sheet. 
