A-CCmmihition of Drinnlin.s. — l^phain. oHl 
Again, my studies of the very massive kame deposits forming 
the greater part of the outermost terminal moraine on Long- 
Island eastward from Roslyn, of the large kame called the Devils 
Heart, rising in a somewhat conical hill 175 feet above the adjoin- 
ing country south of Devil's lake in North Dakota, and of the 
esker named Bird's hill, seven miles northeast of Winnipeg, 
seem to me to demonstrate, beyond all doubt, that their material, 
and probably likewise that of kames and eskers generally, was 
supplied by superglacial streams from the plentiful englacial drift, 
and could not have been brought from drift l)eneath the ice l)y 
subglacial drainage. 
View of thk Ice Age as One (tLaci.\i> Epoch. 
In conclusion, I deem it a duty to state that this reference of 
the drumlins, terminal moraines, kames, and eskers, to rapid a c 
cumulation from previously englacial drift during the deixirture 
of the ice, seems to me lietter accordant with thi' view that the 
Ice age comprised only one great epoch of glaciation, attended by 
oscillations of the ice-border, than withlthe alternative view which 
it 
supposes the ice-sheets to have been at least once and perhaps 
several times almost entirely melted away, afterward being re- 
stored by recurrent glacial epochs. This Ijelief in the unity of 
our glaciation I held during my work on the New Hampshire 
Geological Survey in the years 1874 to 1878: but in my ensuing- 
work on the survey of Minnesota, the peat and forest ))eds en- 
closed between deposits of till in that region led me to accept the 
diialit}' or plurality of glacial epochs as taught l)y Croll, James 
G-eikie, N. H. Winchell, Chamberlin, Shaler. IMcGee, Salisbmy, 
and at present l)y most American glacialists. The recent state- 
ment l)y Prof. (jr. F. Wright of the evidences for the unity of 
Quaternar}' glaciation as the more proltable \iew,''' expresses a 
similar opinion with that to which I have been gradually return- 
ing, during the past year or longer, through the guidance of my 
investigations in this field. Moraines and drumlins are effects of 
secular vicissitudes of climate on the border of the departing ice- 
sheet, which I think to have owed its existence to great altitude 
of the land at the beginning of the (Jlacial period, to have Ix-en 
attended when at its maximum extension and volume by depres- 
•*"Unity of the (ilacial Epoch," .Vni. Jour. !-ici., ITT, vol. \i.iv. ]M). 
351-373, Nov., \mi. 
