1872.] 129 ; (Perry. 
which the waters bore still further, and ordinarily deposited on low 
levels, and at times in basins and depressions which they were made 
to occupy. Thus modified Drift, or the Terrace formation, would 
generally occur as deposits overlying the typical Drift and more or 
Jess arranged by fresh-water. 
What has been advanced suggests that the supposed action of the 
sea in shaping these deposits, not only in the vicinity of New Haven, 
but over most of New England as well, is perhaps a mere fiction of 
the imagination. To render this more evident, and clear up a sup- 
posed difficulty, a word or two in regard to these deposits in the 
neighborhood of New Haven, may be added. Professor Dana says, 
“in sinking an artesian well... 120 yards from the harbor, a bed of 
fine clay fourteen feet thick was struck ... 126 feet below mean tide 
level. Above this clay there were the ordinary sand or gravel de- 
posits of the New Haven region. The clay bed was evidently a mud 
deposit made in the harbor as it existed immediately before the 
deposition of the sand; and as the sand beds of the New Haven 
plain date from the era following the Glacial, the harbor very prob- 
ably was that of the Glacial era.”1 These points are given by the 
author as evidence of a previous elevation. The bed of clay or mud 
just referred to is a sub-aerial deposit, and must therefore have been 
laid down when the place it occupies was above the ocean. The 
typical Drift of the New Haven basin having been already laid bare 
by the retreat of the ice-sheet, this clay-bed was no doubt the first to 
be deposited upon it, with somewhat of regularity, by the waters 
from the wasting ice lying a short way to the north. It was a mud- 
deposit—perhaps a broad mud-flat—and may have covered most of 
the basin. Remembering now that the surface of the ocean, when 
the ice-mass had retreated no further north than Meriden, was still 
much lower than afterward, say 150 feet beneath its present level, 
we readily see that in connection with the wasting of the ice, such a 
sub-aerial clay deposit would naturally find place in the lowest depres- 
sion. And this could be the case without any elevation of the land. 
So the deposition of the sand which overlies the clay might readily, 
and I have no doubt did actually occur, in connection with the sub- 
sequent wastine of the ice-sheet, there being perhaps occasional 
times of great flow, and slight changes in the direction of the cur- 
rents, of the glacial streams. We may thus conclude, without repeat- 
ing the evidence in this place, that these deposits are just what 
1 Paper cited, p. 61. 
PROCEEDINGS B. S. N. H.—VOL. XV. 9 SEPTEMBER, 1872. 
