Pleistocene Geology of Moravia Quadrangle 427 
Moravia, at an altitude of about 820 feet, a polished and striated 
surface attests the vigor of the ice action; that plucking v^as a part 
of the process of disintegration is evidenced by the several stages 
of rounded edges, farther down the slope, developed after the 
removal of rock along bedding planes. The basal load was 
sufficient for most active planing or abrasive work. On the same 
side of the valley but northward, similar striated and polished 
surfaces have been noted. Also on the opposite valley wall, the 
vigor of the ice is indicated by the well rounded and polished 
ledges. Southward from Locke, however, evidence of this nature 
is wanting. In general it may be said that evidence of the^most 
active ice-erosion is not found over 150 feet above the present 
flood plain. 
Fig. 27. A generalized representation of glacial erosion in a longitudinal valley. 
The observations on which this deduction rests were made about the Owasco valley 
from Locke northward. 
The resultant, then, of ice-erosion is to deepen longitudinal 
valleys, producing oversteepened walls, the horizon of accentuated 
erosion commencing in the Moravia valley somewhat below the 
900-foot contour. Consequently, in cross-section, valleys that 
preglacially had a sharp V-outline, are given more of a U-shape 
outline, while mature valleys are made composite by having a U- 
outline cut approximately along their normal axes. 
Fig. 27 attempts to generalize the results of ice-erosion which, 
in accordance with the above discussion, may be given three 
ranges showing variation in effectiveness. First, in the highest 
altitudes, a range of mild erosion; second, next below, a range 
of inefficient erosion; and third, toward the valley axis, a range 
of vigorous erosion. 
Whether this enormous over-deepening of certain valleys was 
accomplished by the ice-sheet while the margin was far south. 
