Perry.] ; 98 [February 28, 
show that the work done, during the winter of the ages, was pro- 
digious. While familiar with the facility shown by some in explain- 
ing away facts, or making them bend to a preconceived theory; 
while also well aware that, in given cases, large depositions are rap- 
idly made, and great changes effected in a short time; I am still re- 
minded, that such depositions and changes are the exception; that 
the whole of New England is covered with loose and more or less 
finely comminuted material; that this could not have been ground 
from the solid rock, and reduced in large amount to the condition of 
a powder, in a moment; and that, consequently, this material, in 
passing through so many changes, and assuming its present position, 
may have required a long period, even in the geologic sense of the 
term. Ido not say that this is the fact; I simply state the problem, 
that it may lie open for solution. 
With this aim in mind, it may be well that some of the facts 
already mentioned be again referred to, and now briefly set forth, in 
the light furnished by the glacier hypothesis. This is important, 
both that they may be seen as distinctly exhibited, under this aspect 
of the question, and because they are perhaps suited to give a faint 
indication of the relative duration of the Glacial times, in their sev- 
eral divisions; the later probably being far shorter than the middle, 
and possibly even than the opening portion of the Ice-period. With 
this purpose in view, I proceed to notice 
§ 13. The Action of the Ice-Sheet. 
(1.) As attested by the underlying rocks. The consideration of 
this action, as calculated to throw a glimmer of light upon the point 
in question, may at the same time enable us to determine whether 
the facts be explicable on the ground of the glacier-hypothesis. The 
wearing agency of ice is very powerful in itself considered; and it 
must have been peculiarly energetic, as brought to bear in the oper- 
ations specially under consideration, if one may judge from the many 
effects which remain as intelligible traces of its presence, and as 
trustworthy witnesses of what was once going on in this region; and 
these effects may be looked upon with propriety, as direct conse- 
quences of glacial agency. 
First of all, erosion has occurred, and to an immense extent. As 
an evidence of this, reference need be only made to the vast amount 
of denudation which has taken place on the surface. In many in- 
