Perry.] 112 [February 28, 
peaks. Of course, under these circumstances, the hill-sides would 
be closely pressed and rubbed, blocks of slate and limestone detached 
from their places, and borne along at first as lateral moraines, and 
on uniting as medial moraines, on the summit of the ice-sheet. The 
ice gradually wasting, there would be changes in the direction of the 
moving mass, determined among other conditions by the character of 
the underlying surface of solid rock, thus causing many variations, 
while on the final dissolution of the ice, the angular erratics would 
be left, as they now occur, more or less dispersed over the surface of 
the typical Drift. 
Substantially the same explanation is applicable to similar phenom- 
ena in other portions of New England, and perhaps in part toa 
track of boulders in Huntington, Vt. It is about two miles in length, 
some forty or fifty rods wide, with a nearly north-south trend, and 
entirely made up of uncouth angular blocks, strikingly different from 
any known rock in the neighborhood. Hence it is probable that 
these are true erratics, and were borne a long way on the back of 
the ice-sheet. And these travellers, like the Richmond boulder- 
trains, belonged to the main glacial mass; this is clear from their 
anescaoen seen in connection with the fact that they extend * from 
one valle to another, passing obliquely across a steep intervening 
hill. . 
Such in brief, is the explanation I would give of these lines of 
boulders,—an explanation suggested by the study of these strange 
remains in the light derived from the researches of Professor Agas- 
siz on the existing glaciers of Switzerland; an explanation, which | 
takes from these instances the exceptional character which has been 
ascribed to them, since it regards them as legitimate concomitants of | 
the great winter of the ages; an explanation which, while it is in | 
entire consonance with all the known facts connected with the glacia- | 
tion of the country, has the great advantage of requiring no resort to | 
an arbitrary and unsupported hypothesis of continental depression. 
During what was the Later Glacial period in New England, mo-_ 
rainic masses were formed in comparative abundance, and, while 
some of them were no doubt obliterated long ago, not a few remain | 
to tell their quaint and characteristic story. In Vermont, they cccur | 
in nearly all the principal valleys, and particularly lateral moraines 
along their sides, especially in the more elevated portions. I have 
also observed them in Maine, and, if I do not entirely mistake the | 
evidence, occasionally in Massachusetts. Under these circumstances 
