Upham.] O [Nov. i6, 
and Davis and Salisbury in this country, look on the druinlins 
as analogous to the sand hars of streams. Professor Davis 
writes : — 
"In view of the irregularity of the surface on which the ice-sheet 
moved, and of the greiiter weakness of some rocks than others, 
we must suppose an irregular velocity in the motion of the ice 
and an unequal distribution of the rubbish beneath it. If the 
faster motion at one place causes an excess of erosion there, the 
slower motion at another place may bring about an excess of 
deposition. This difference of action is known to prevail between 
the central and marginal parts of glaciated areas ; and the local 
accumulation of drumlins in an intermediate region gives a 
smaller example of these two parts played by the ice. If the 
causes of the irregular motion of the ice lie in the general 
form of the country, the location of faster and slower currents 
will be relatively permanent ; the districts of faster currents would 
be found where the greatest volume of ice is allowed to pass, and 
some of the points of retardation may be the seats of long con- 
tinued drumlin growth."^ 
For accordance with this theory, the areas bearing drumlins 
should be determined chiefly by the topography and rock forma- 
tions, which, however, seem to have exerted little influence. 
Furthermore, the rapid accumulation of the drumlins, shown by 
my last paper on this subject before this Society to have been in 
some cases at the rate of from one to six feet or more of till yearly 
added to their surface, appears inconsistent with the belief that 
they were mostly supplied from drift immediately before eroded 
from the land surface and transported by subglacial dragging to 
its place in these drift hills. 
3. PROBABLE ACCUMULATION OF THE DRUMLINS FROM EN6LACIAL 
DRIFT. 
The origin of the drumlins may be better understood, or at 
least to the writer it seems more intelligible, if we inquire how the 
drift which had been englacial until the time of departure of the 
ice would be deposited. 
It is evident that the ice-sheet in its passage over a mountain- 
'Amer. journ. sci., ser. 3, vol. 28, Dec, 1884, p. 415. 
