THE SCIOTO ILLINOIAN LOBE 491 
the most diligent search has not revealed any evidence of glaciation 
is somewhat puzzling, but very convincing of the fact that the final 
demarkation of the glacial boundary is a problem of time. 
In establishing the relationship of these valley dependencies of 
the Ilhnoian ice-sheet to the Scioto lobe, and in determining whether 
they are tongue-like extensions of the ice-mass at its period of greatest 
development, or at a later retreatal stage, three townships, Perry, 
Hanover, and Mary Ann, of Licking County, have been carefully 
Fic. 4.—Looking south of east. The wooded area on the extreme left is rock, 
as is also the slope above the buildings on the right. The intervening ridge of drift 
marks the position of the ice-tongue that extended eastward from Wilkins Run. 
studied, while like attention has been given to portions of adjacent 
townships. In valleys trending in general with the direction of ice- 
movement, the problem is one of distinguishing the unmodified drift 
from the deposits of entirely extra-glacial waters, and of determining 
the drift-covered portion of the valley walls. 
It has been established that ice did not enter Perry township (Fig. 
2) from the north or west,* and that the township was not glaciated 
t F. Carney, loc. cit., p. 124. 
