228 
Harmon A. Nixon and Dexter J . Tight 
minal moraines obliterated nearly all the minor drainage chan- 
nels, leaving little besides the very general divide lines. 
In the retreat of these ice sheets, the ice departed from the low 
areas last. Thus we have at each retreat of the Illinoian and Wis- 
consin sheets a large lobe of ice protruding down the Scioto Valley. 
From this lobe there extended eastward a tongue of ice which 
followed very closely the topography of the Raccoon Valley.^® 
Influence of glacial invasion on subsequent drainage of area. 
We can now see the influence that this tongue of ice exerted in 
shaping the drainage features which form the present topography 
of the MooFs Run area. The topographic map (Granville quad- 
rangle) shows that Moot’s Run lies on the side of the slope of its 
divide and not at the base of it; this divide, which is roughly 
parallel to Moot’s Run, has a northwest-southeast direction. 
’ At one time it probably formed the rock wall of the old Raccoon. 
The outcrops' of rock in the Moot’s Run gorge represent the north- 
ern limit of this rock slope. From a study of the outcrops along 
Moot’s Run and its tributaries, we have outlined the most likely 
extension of this wall through the area. 
What would be the effect on drainage lines, if a tongue of ice 
from the Scioto lobe halted for some time against this divide? 
That such a halt did take place, we are convinced from a study 
of the extensive moraine deposits on the west side of the Moot’s 
Run gorge. We also infer that in this area the tongue of ice 
conformed very closely to the topography of the region. Mather^ ^ 
and Scheffeh^ speak of a similar conformity in the adjoining areas. 
When the ice stood in the Moot’s Run area, in the position above 
described, the axis of the divide inclining toward the ice, the 
drainage which flowed normally from this incline toward the 
Raccoon Valley would be blocked, and as a result would have to 
take a course along the ice front. This volume of water, aug- 
mented by the enormous amount supplied by the melting ice, 
and employing as tools the drift from the ice, would easily cut 
through the rock walls, which are of a very soft texture, mostly 
shale. The places where it cut across the foothills of the old 
Scheffel, ^‘The Origin of Spring Valley Gorge,” Bull. Set. Lab., Denison Univ., 
vol. xiii, 1907, pp. 154-166. 
Mather, Bull. Sci. Lab., Denison Univ., vol. xiv, 1909, p. 176. 
Scheffel, loc. cit., p. 164. 
