Upham.] 
238 
[April 17, 
a typical drumlin, was removed, its central portion contained, at an 
elevation probably ten feet above the present surface of Fort Hill 
Square, a bed of horizontally stratified clay, free from boulders and 
gravel, enclosed within the till, having an extent of a few rods, but 
not continuing in any direction to the natural surface on the slopes 
of the hill. In New Hampshire modified drift has been observed in 
several places enclosed in drumlins and in smooth rounded masses 
of till, nearly related to drumlins, which slope downward from 
prominent hills of rock, either on their stoss or lee sides or often 
on both these sides . 1 Professor Davis tells me, also, that in the 
southern part of the belt of very abundant drumlins in central New 
York, their sections frequently show stratified gravel and sand un- 
derlying the till, and that often the relationship of these formations 
is such as to prove that the stratified beds were somewhat eroded 
before the accumulation of the till, as by an advance of the ice- 
sheet over a preglacial or interglacial deposit. In this important 
respect these sections differ from those of Third and Fourth Cliffs ; 
but the latter seem to be nearly allied, if not identical, in struct- 
ure and origin with the massive rounded drift-hills, consisting of 
till on the surface and of underlying beds of gravel and sand, which 
President Chamberlin has called veneered hills. Excellent ex- 
amples of these are found in Madison, Wisconsin, much larger than 
the drumlins of Scituate. 
Thin layers, seams, or veins, of sand and fine gravel, deposited 
by water like all the modified drift, are occasionally found enclosed 
in the till of drumlins, but are rare, sections of these hills being 
usually composed wholly of the unstratified till, deposited directly 
from the ice-sheet. An instructive section, showing such a thin 
sand layer, was exposed last summer in the excavation of the north- 
east slope of Central Hill, Somerville, on the site of the new Win- 
ter Hill station of the Lowell railroad. The whole excavation, 
about twenty feet in height and several rods long, was ordinary till, 
excepting where it contains one seam of clean, coarse sand, from a 
half inch to three inches thick, which was seen along an extent of 
about fifty feet from northwest to southeast and also nearly as far 
in a transverse direction. Its elevation was two to six feet above 
the railroad track, with an inclination nearly like that of the hill 
slope. Throughout its whole area observed, it was continuous in 
a somewhat regular course, without crumpling or considerable dis- 
1 Geology of New Hampshire, vol. iii, 1878, pp. 289-291. 
