Pleistocene Geology of Moravia Quadrangle 343 
rarely sufficed to remove the drift sufficiently for much rock- 
cutting, so that there are no post-glacial gorges, though there are 
many sags or small valleys representing post-glacial stream ero- 
sion. Near Groton on the east side of the valley two streams for 
short distances are on rock, but this is nearly a mile from the floor 
of the main valley. North of Centerville we find the gorge of 
Dry Run (fig. 6), already alluded to. On the west slope of the 
Owasco valley we would anticipate many glens, since the steep 
fall should encourage rapid erosion, but the creeks have such 
limited catchment basins that they have been unable to produce 
any marked channels in the slopes. 
At Montville the stream coming from the north flows in the 
last mile or so of its course, between rock Walls. This stream 
has a fall of fifteen to twenty feet over the Tully limestone, which 
forms a conspicuous shoulder and is easily quarried along the east 
wall of the valley as far south as Locke; and a short distance down 
stream a slightly greater fall over hard layers in the underlying 
shale, the latter fall being used by the village of Moravia in con- 
nection with its electrical plant. 
Northwest of Lake Como is a slight post-glacial gorge cut in 
some of the harder layers of the Portage sandstone. The small 
basin of this stream is apparently all out of proportion to the 
gorge-cutting here present. The explanation of the condition, 
however, is apparent as one follows the highway toward North 
Summer Hill. Just east of this village, at about the head of the 
valley whose gorge we are describing, is found a loop of moraine 
(p. 366) marking a position where the ice stood for some time. 
The gorge-cutting was done when the valley was carrying a 
burden of ice-front drainage. 
About a mile east of Sempronius one passes between rock walls 
in following the highway into the Skaneateles valley. These 
rock walls cannot be connected genetically with present drainage; 
nor, from deductions that one would make, has the former develop- 
ment of drainage in the area developed the gorge. The only 
reasonable hypothesis for the gorge cutting here represented is 
that the erosion was done by ice-front waters, and this supposition 
is sustained by the nature of the channel which leads into the head 
of this rock gorge from the north (p. 432). 
In the southwestern part of the quadrangle near Asbury is 
another gorge which presumably represents the work of post- 
