398 The American Geologist. June, 1894 
ground moraine, the true dm inline and the drumlinoid till 
slopes of various kinds are strikingly local and irregular in 
distribution. 
The greater part of the drift-covered area is free from 
these hills ; and where they do occur they are generally bunched 
together. There is. moreover, in parts of New England, a 
striking parallelism between chains of drumlins and bands of 
moraine. While the individual hills have commonly a north 
and south extension, collectively they have an east and west 
grouping. 
Also, just as the moraine is thicker in some places than in 
others, so they are more numerous and deeper in certain areas 
than in others. At times their depth is considerably greater 
than the deep part of the till sheet in the area. These facts 
suggest a certain likeness between moraines and drumlins 
which must be kept in mind in studjdng the origin of these 
peculiar hills. 
(b) Resemblance to Drumlinoid Hock Jl ills. — There can be 
no student of glacial geology who has not been struck by the 
marked resemblance between drumlins and drumlinoid rock 
hills in glaciated areas. In my own case, although reared 
among the drumlins of the Boston region, I was, in my first 
glacial work in central Massachusetts, misled into classifying 
rock hills as drumlins on the basis of their form alone. The 
gneiss hills of New England are in many cases drumlinoid in 
outline; and at times the resemblance between a thinly drift- 
coated hill and a drumlin is most striking. Even hills barren 
of till are frequently lenticular. 
While this is true for New England it is even more typi- 
cally shown in central New York. There are scores of hills in 
that region, which, in a photograph, could be easily passed for 
typical drumlins and which need a visit to prove that they 
are not drift hills. 
There is a certain rhythm of ice erosion which expresses it- 
self on a small scale in the production of roches moutonne'es, 
on a larger scale in the carving of drumlinoid rock hills, and. 
I believe, on a still larger scale, in alternations of erosion and 
comparative freedom from erosion at intervals of many miles.* 
*This point is presented in ;i paper in the Hull. Geol. Soc. America. 
vol. v. 1894, .,. 352. 
