Perry.] 132 ; [February 28, 
the mode in which the marine terraces were formed. Whether there 
were a previous slizht depression of the continent, or not, of course 
the sea relatively to the land must have been somewhat higher than 
it is to-day, in order to deposit these strata. . 
Now, according to Prof. Dana, there was a very extensive subsi- 
dence embracing ‘‘a large part of the continent.’”?4 On what stable 
ground such a statement can be made to rest, I have up to this time 
failed to discover. So far as trustworthy evidence goes, this depres- 
sion, if there were any, was very small in southern New England. 
In Brooklyn, on Long Island, a few sea-shells have been found in 
beds belonging to this period, some thirty feet above the ocean. In 
Boston and its vicinity, similar marine remains occur in this deposit. 
They attest that the sea, relatively to the land, was formerly some- 
where between 50 and 100 or 125 feet higher than it is to-day. 
Diligent search, renewed at intervals through a long series of years, 
_ has failed to reveal to me any satisfactory proof of the presence of 
the ocean, during the terrace period, either in the Mass., or in the 
Vt. and N. H. portions of the Connecticut River valley. The same 
is true, so far as my examination has extended or I have been able to 
learn, of the North River basin above New York. In Maine, at 
Portland, and in other parts of the State, along the seaboard, also at 
Lewiston and in several other places a short distance inland, there is 
positive evidence of a relative change of level. It must have been, 
in given localities, about 200 feet. I have found marine remains 
peculiar to the period, in north-western Vermont, at a height of 
430 feet. Similar remains occur on Montreal Mountain, about 460 
feet above the ocean. It is said that, very far to the north, though 
on the border of the sea, there is evidence that the relative change 
of level has been much greater. Meanwhile a careful examination 
of Geological Reports, and an attentive scrutiny of the superficial 
deposits, at a great number of points between Hastern Canada and 
Minnesota, have failed to afford me any evidence of recent marine 
remains to the west of the meridian of Oswego, N. Y. Such is sub- 
stantially what is known of the matter in all this region; indeed, I 
am aware of little additional evidence of relative change of level, or 
of what some regard as a continental depression. 
It thus appears that a small part of New England, with a very lim- 
ited portion of Northern New York and of Canada, were slightly be- 
1 Paper cited, p. 66. 
