Pleistocene Geology of Moravia Quadrangle 423 
slopes lying between West Groton and Locke; likewise on the 
two salients southeast of Moravia, as well as several north- 
ward sloping areas found on the eastern side of Fall Creek 
valley northward from McLean. Of a similar genesis too are 
some scattered areas in the southwestern part of the quadrangle. 
This condition in the uplands has been discussed as illustrating 
areas where the till is thin (p. 381). The slopes alluded to afforded 
the ice the proper obstruction attitude for very effective erosion. 
In general, however, the subject of ice-erosion is thought of as 
applying more particularly to longitudinal valleys. Is the entire 
transverse profile of a valley altered by ice, or is the erosion con- 
fined largely to the lower parts The observations bearing on 
this point, made in the Moravia quadrangle, are best illustrated 
in the Freeville-Moravia valley northward from Locke. As men- 
tioned above, this segment of the valley offered the most favorable 
conditions for ice erosion. A generalized statement of the con- 
clusion from the data observed is: In this longitudinal valley the 
most vigorous erosion was operative along the contours below 
900 feet. Above this plane is a zone of less active erosion, while 
still farther up the ice did considerable abrasive work. In the 
lower contours of the valle}^, however, the power of an ice sheet to 
deepen longitudinal dissection lines is very impressive. 
The above generalization is based on a detailed study of the slopes, 
and upland above the 900-foot contour; what the ice did below 
this general altitude of 900 feet is perfectly clear. Folded beds, 
rather completely disintegrated, shown in figure 25, may be seen 
in a quarry a short distance northeast of Locke. The fold as 
exposed in this cross-section, which is oriented S. 30° east, has 
a tilt of approximately 51°. The disturbed zone is but a little 
over one foot in thickness and is made up of thin sandy shale 
layers beneath which is a sandstone bed about six inches in thick- 
ness. The quarry has been opened for removing the heavier beds 
which are subjacent to this six inch layer of sandstone. Over- 
lying the distorted beds are about two feet of drift and quarry 
rubbish, the till part of which in all probability is not in place. 
Figure 26 shows another folded horizon a mile and one-half 
north of Moravia. This fold inclines about 36°, and the exposure 
is in an east-west line. The folded area is on the eastern slope 
of the valley, and the fold itself is turned against gravity. Llere 
too the disturbed beds, about eighteen inches in thickness, con- 
