An Esker Group South of Dayton, Ohio 
29 
Altitude of these deposits. The elevation of the area above the 
valley is partly due to the base upon which it rests. This is shown 
particularly in the kame region, the inside slopes of which are 
much shorter than the slopes facing the valley, a condition explain- 
able by slumping within the area and erosion around it by the 
Miami as before stated. 
In this connection it may be suggested that possibly gradation 
has greatly modified the original eskers. At the time of ice-with- 
drawal these forms, particularly if sub-glacial in genesis, must have 
been left with little or no vegetative protection. It cannot be deter- 
mined how long a time was required before plant life secured a 
Fig. 5 (F. Carney). Kame area immediately west of esker no. 2. Camera 
facing north. Barn rests on a long ridge of kames. 
good foothold, but it is reasonable to suppose that the interval 
was sufficient to permit considerable weathering even on such 
narrow forms as eskers. With the eskers in question is it not prob- 
able that after the constituting material had assumed its natural 
angle of repose they may have been considerably lowered by 
gradational processes ? Such processes would also reduce the 
effect of height by partially filling the trough. 
Composition of eskers. A layer of bowldery till spreads over 
the group. This varies in thickness, sometimes being five or six 
feet deep. Such a deposit, of course, supports the theory of sub- 
glacial origin, representing as it does the melting of a body of 
debris-laden ice above. The gravel beneath this till in the eskers 
is composed of a large percentage of Ohio limestone intermingled 
