GLACIAL EROSION IN LONGITUDINAL VALLEYS 727 
noted along the slope within a mile and a half north of Moravia. 
Some of these were less distorted than the one shown in Fig. 3, one 
being fairly symmetrical, and possibly to be explained by buckling, 
since it is several feet below the reach of frost work. But in each 
case where the axis of the fold was inclined the inclination was up 
the slope. 
It.is felt, therefore, that we are dealing with the work of ice in 
deforming subjacent strata; we have selected cases to illustrate the 
work of this ice along two lines, one connected probably with the 
general movement of the ice sheet, or at least the linear movement of 
a strong valley lobe, the other connected with the outward spreading 
of a valley lobe. 
GLACIAL EROSION 
In reference to the altitudes of the localities where folding has 
been noted: The disturbed strata of station 2 lie approximately 
1,140 feet above sea-level. The area of disturbed strata north of 
Moravia lies within 1,080 and 1,160 feet altitude. Very diligent 
search at lower and higher ranges than these has not revealed any 
similar phenomena, but has, however, given much information on 
the subject of ice-erosion. 
Fig. 4 is a photograph of a freshly uncovered rock surface about 
a mile and a half southwest of Moravia near the foot of the steep 
valley wall. The well-rounded angles, showing the polishing work 
of the ice as block after block of the thin bedded sandstone material 
has been removed, the general smoothing of the whole surface, the 
irregular gouges and the striae attest the vigor of ice-work here. 
Several similar areas were likewise noted; the one shown, however, 
is typical and different from the others only in revealing a larger 
surface. Here the average direction of the striae is $.13°E., a 
direction that shows the control exercised by the valley. This surface 
has an altitude of about 790 feet, standing but slightly more than 50 
feet above the inlet stream near the base of the valley wall. The 
slope of the polished surface has the general grade of the valley wall 
immediately above and below. While this surface is very illustrative 
of the corrasive work of ice, it is felt nevertheless that the processes 
of ice degradation which it represents are of the same type as have 
probably been effective in giving the valley cross-section its U-outline. 
