The Origin of Drumlins. — Tarr. 395 
Recently Upham* has advanced the hypothesis that drum- 
lins are formed in the ice by a shearing motion and conse- 
quent accumulation. 
2 — Objections to these Theories. 
Numerous objections have been urged against the last theory, 
those by Chamberlinj and Davis* being particularly strong 
and proving, apparently, that it is not applicable, at least as 
a general explanation. Professor Davis suggests, however, 
that this ma}' be one of several causes for a phenomenon 
which is conceivably capable of explanation b} T several dif- 
ferent theories. 
The explanation suggested by Professor Shaler appears to 
be open to a fatal objection. This is that, excepting near tin- 
surface, the drumlin drift shows no signs of disintegration. 
and is in no way different from the ordinary glacial drift. 
Unless the time of deglaciation, or the interglacial period, is 
conceived to be very brief this theory does not explain the 
facts. 
The problem is therefore reduced to the consideration of 
the two remaining hypotheses. With reference to the one 
most currently accepted, the constructional theory, it has al- 
ways been difficult for me to conceive the overburdening of ice 
in such a way that it may temporarily and locally deposit these 
narrow and comparatively small, though relatively deep drift 
deposits. By what action is this accomplished and in what 
manner does the process act? These are points which, after 
a careful study of the literature, 1 have been unable to under- 
stand. This is, I am aware, not necessarily a serious objec- 
tion to the hypothesis; but before accepting an hypothesis one 
must find in it either proof or possibility. 
If we grant this power to ice, it would appear that there 
should be some apparent cause for variation in currents and 
in deposition. But drumlins occur in regions so different 
that there seems to lie no connection with topography or sup- 
ply. They are found in and south of hard crystalline rocks 
*Am. Geologist, 1892, vol. x. pp. :;:!'. >-:;<>'.': Proc, Boston Soc. Nat. 
Hist.. 1892, vol. xxvi. pp. 2-17; Bull., Geol. Soc. Am., 1893, vol. i\. 
pp. !). 10. 
fJournal of Geology, 1893, vol. i. p. 259. 
{Prop: Boston 9oc. Nat. Hist., 1892, vol. xxvi. pp. 17-23. 
