Pleistocene Geology of Moravia Quadrangle 381 
Some quite extensive areas are particularly free of drift. These 
generally are regions of active ice erosion. One such locality 
exists south of Locke, commencing 'with the i20C-foot contour, 
and embracing a region of some five or six square miles north- 
ward of West Groton. The thin veneer of drift present consists 
of local stones embedded in an exceedingly slight amount of other 
drift. Some quite extensive plots are free of any drift, the local 
rock presenting a bare surface. Another similar locality is found 
southwest of Moravia, on the ascending slope which is reached 
by the first road running eastward from the valley. Here the 
horizon of very thin drift commences likewise at about the 1200- 
foot contour, and comprises three or four square miles. The 
description given for the area south of Locke is applicable to this 
region. 
These two areas are typical of several others which are usually 
found on rock outliers, presenting a prow towards the northwest; 
in each case the longer axis of the fairly drift-free surface is quite 
parallel to the general direction of ice movement. 
(2) Terminal Moraines. As the ice retreated across the Mo- 
ravia quadrangle its front kept a general northeast-southwest 
position. The minor irregularities in its front gave rise to the 
several forms of valley drift discussed above. While the ice stood 
at a certain place in a valley, and drift was accumulating about 
the margin of the tongue, deposits were also forming away from 
the valley, thus registering the position of the ice in the uplands. 
If after the ice had kept a stationary front for some time, by feed- 
ing as fast as it wasted, there followed a period of much more rapid 
melting, thus causing the front to retreat rapidly, no pronounced 
accumulation of moraine would be formed; then if this period was 
I succeeded by one in which the feeding and melting of the ice were 
j about equal, thus depositing in a narrow strip all the debris car- 
ried by this wasted ice, we would have one more band of moraine. 
If, on the other hand, we do not have these alternating areas of 
thick and sparse drift, but instead an almost continuous heavy 
' sheet of drift, which in fact is a wide moraine, we conclude that 
the ice wasted rapidly but fed on at but a slightly less rate; with 
' such a relation the front of the ice receded slowly, and much 
I debris accumulated. 
The peculiar feature of the ice-front and the resulting arrange- 
ment of the drift in this quadrangle is its direction. The Cayuga 
