The Origin of Drumtyns. — Tarr, 393 
THE ORIGIN OF DRUMLINS. 
By Ralph S. Tarr, Ithaca, N. Y. 
CONTENTS. 
Page 
1. Statement of Theories 393 
2. Objections to these Theories 395 
3. Indications of Destructional Origin 397 
(a) Distribution 397 
(b) Resemblance to Dramlinoid Rock Hills 398 
(c) Drumlinoid Form of Overridden Moraines 399 
(d) Flutings on Drumlins 399 
4. Consideration of Objections to Destrnctional Hypothesis 399 
(a) Assumed Absence of Stratified Drift 400 
i. General absence of sections 400 
ii. Moraines not always stratified 400 
iii. Drumlins containing stratified drift 401 
(b) Assumed Absence of Boulders 403 
(c) Peculiarities of Distribution 404 
5. Re-statement Of Destructional Hypothesis 404 
6. Summary 406 
1. — Statement of Theories. 
Three theories to account for lenticular hills or drumlins 
have come prominently before geologists, and there is at pres- 
ent a division of opinion as to the value of these. Of late, 
however, there appears to be a tendency among the majority 
of glacialists to look upon one of these as more probable than 
the others; and there also appears to be a tendency to over- 
look the fact that there are strong reasons to suspect that one 
of the other theories may also furnish a true explanation. 
This paper is written, not with the object of advocating this 
theory to the exclusion of others, but to bring forward such 
arguments as the author finds, in his own mind, to be indica- 
tions that it cannot be neglected as a working hypothesis. 
As early as 1870 Professor Shaler* suggested that these pe- 
culiar drift hills, in the vicinity of Boston, were the remnants 
of a sheet of drift, modified by the action of rivers, waves, 
etc., and obtaining their two prevailing directions from un- 
derlying rock cores. He has more recently somewhat modified 
this view by supposing that a deposit of the first glacial 
epoch has been worked over and carved out chiefly by ice 
act ion. f 
A modification of this latter theory is that suggested by 
*Proc. Boston Sue. Nat. Hist., 1870, vol. xin. pp. 196-204; [llusf ral ions 
of tlif Earth's Surface, 1881, \>. 63. 
fSeventh Annual Report, 15. 8. Geol. Survey, p. 321; Ninth Annua! 
Report, U. S. Geol. Survey, pp. 550-551. 
