1872.] 65 (Perry. 
and some of them have presented it with not a little ingenuity and 
acumen. Prof. Dana, however it may have been in the past, now 
rejects the view outright, at least so far as its application to New Eng- 
land is concerned. And yet, in the paper under consideration, he ad- 
vances one, and only one direct item of evidence against it, viz., that 
the boulders so often met with in New England are, for the most part, 
derived from rocks not far distant from the localities in which they 
are now found.! A few will be disposed to take this bare statement 
as deciding the question at issue. As.no one, however, should 
be satistied with a decision resting on the mere authority of names, 
as there is also a great conflict of opinion in regard to the explana- 
tion of the phenomena, it becomes important to examine the matter 
critically, that we may see whether icebergs be sufficient to account 
for the work wrought, in whole or in part, and whether it 
was actually effected by them or not. 
The iceberg hypothesis implies (and if this be the explanation 
adopted most of the facts to be explained compel us to presume) 
that this region was some four or five thousand feet beneath the 
ocean during the whole or a major part of the ice period; that there 
was an arctic continent abounding in separate glaciers, or shrouded 
in a broad sheet of ice, from the southern limits of which huge blocks 
constantly broke off and floated away, in the form of bergs; that 
these passed over what is now New England, and did the work to 
which reference has been made, eroding, smoothing, striating the 
surface, covering it with debris, and producing the various other 
effects already named. Some, again, have supposed that the work in 
southern New England was largely wrought by icebergs derived from 
glaciers in the White Mountains. This last is the phase of the sub- 
ject which Prof. Dana has more particularly noticed, and which he 
has, for the most part very well disposed of.2 To the statements he 
has made it may be well to add, that so great a depression would 
have allowed small space in New England for the formation of gla- 
ciers. ‘The summits of the White Mountains at the very best could 
have been only a cluster of islands, and thus must have failed to 
furnish the requisite conditions for the accumulation of any extensive 
ice-masses. So had there been such a submergence, testimony would 
have been borne to the fact by stratified marine deposits. There 
are, however, no beds of this kind in any portion of the drift proper, 
1 Paper cited, pp. 48, 49. 2 Paper cited, p. 49. 
PROCEEDINGS B. S. N. H. — VOL. XY. 5 AUGUST, 1872. 
