39^ NEW YORK STATE MUSEUM 



problem of drumlin formation. It is recognized that no single 

 drumlin area may exemplify all the features belonging to these 

 drift forms, but the New York area includes such a large variety of 

 forms and relationships that it should illustrate the fundamental 

 mechanics and most of the phenomena. 



For the reader who may not be familiar with this form of the 

 glacial drift a brief description of its general character will be 

 appropriate. That these hills are of glacial origin is evident from 

 their location always within the glaciated territory, their superficial 

 position and their composition which is compact till or ground 

 moraine, at least in New York. Their molded forms show the over- 

 riding effect of the ice and they are believed to have been shaped, if 

 not constructed, under the relatively thin and weaker border of the 

 continental ice sheet, along the zone where the ice in its transport- 

 ing power became incompetent to carry further its drift burden. 

 Their forms vary from mounds to long, slender ridges ; and their 

 size from massive, conspicuous hills, ioo or 200 feet high, to indefi- 

 nite swells of the drift surface. 



The history of the earlier study of drumlins may be read in the 

 article by W. M. Davis, " Distribution and Origin of Drumlins " 

 [i"^p. 437]; and also in the papers by Warren Upham, specially 

 those of the years 1889, 1892 and 1893 [see p. 438]. A brief synopsis 

 of the description by Kinahan and Close of the type drumlins in 

 Ireland is appended as pages 435-36, with a copy of part of their 

 map [pi. 47]. 



The following names were formerly applied to the drumlin forms: 

 parallel ridges, Sir James Hall, 1815 ; drumlins, H. M. Close, 1866 ; 

 parallel ridges, Shaleiy 1870 ; lenticular hills, Hitchcock, 1876 ; 

 whalebacks, Matthew, 1877 ; drums and sowbacks, J. Geikie, 1877 ; 

 parallel drift hills, Johnson, 1882 ; mammillary and elliptical hills, 

 Chamberlin, 1883. 



The name " drumlin " (derived from the Celtic and meaning 

 "little hill") was first applied by H. M. Close in 1866 to these drift 

 hills in Ireland. The various names formerly applied have by 

 common consent given way to the present name, which was intro- 

 duced in this country by W. M. Davis in 1884 



Drumlins are so diverse in their form, and possibly in their pre- 

 cise origin, that any terse definition must be somewhat vague. The 

 smooth form, convex profile and parallelism with the ice flow 



