The Kavies of the Oriskany Valley. — Harris. 389 
would discharge into the lake, and build up detrital deposits 
at the sides of the valley. Doubtless there were also oppor- 
tunities for escape at the end of the ice-tongue, in the middle 
of the valley ; but it must be remembered that the bottom of 
the ice-tongue lay submerged in the lake, and that this water 
would retard any subglacial stream which might discharge at 
that point, while the side currents, flowing down from a higher 
level, along the junction of ice and rock, would have a consider- 
able fall and a more rapid current, adequate to the transporta- 
tion of much more and much coarser detritus than could be fur- 
nished at the end of the tongue. It would be of interest, for 
any having the opportunity, to test this explanation by ob- 
serving the distribution of washed drift at the points of dis- 
charge of the streams from existing glaciers, could such be 
found under conditions which present a sufficiently close 
parallel. 
Another fact of interest emphasizes the close connection of 
these kames with glacial conditions. The materials of which 
they consist are exposed to view in numerous railroad cut- 
tings, and, as was said above, they contain, among other rock 
fragments, numerous pebbles of the red Salina shale, which 
occurs in place several miles further north. This shale is 
very soft and friable, even where its ledges are excavated to 
a depth of many feet, and the pebbles themselves are so frag- 
ile that it is exceedingly difficult to get one out of the gravel 
unbroken. Yet they are well rounded, showing that they 
have undergone considerable battering in their journey; and 
they are in close association with pebbles of much harder ma- 
terials, with which they must have been brought into frequent 
collision on their way to their present resting place. It is 
easy, therefore, to see that during the process of transporta- 
tion they must have been much harder than they now are. It 
is not impossible that their presenl softness may be due en- 
tirely to chemical decay, caused by substances broughl by 
percolating water since their deposition; but the fragility of 
the shale where undisturbed, even in a fresh deep excavation, 
makes this at least questionable. It seems more probable that 
the shale rock had become saturated by percolating water 
from the surface when the ice sheet advanced over it. and 
that the low temperature due to the presence of the glacier 
