420 J. D. Dana—Depression of Southern New England 
ent level in the Champlain period, the evidence from the struc- 
ture of the beds and from the Alluvian deposits suggests that 
the region was submerged to a depth of at least 45 feet. 
But if so deeply submerged, why should the terrace plain 
slope off gradually toward the coast and have no line of old 
beaches across it? And why is there no 45-foot sea-shore for- 
mation or terrace along some part of the bases of the hills 
ways in which such a slope in the plain may be sup- 
posed to have resulted are the following:—(1) By a subsidence 
causing a bending downward of the coast-region after the ele- 
vation of 45 feet had taken place.—(2) By an elevation of the 
land which should be 45 feet four miles from the coast, but 
10 to 12 feet near the coast.—(8) By the sweeping action of the 
flood giving a slope to the deposits toward the Sound an 
neath its waters, and preventing the formation of seashore flats 
at the water’s level.—(4) By the denuding action of the waves 
and tidal currents as the land rose to its present level.—{(5) By 
the deposits, because of a diminution in the amount of material 
southward or increase in the depth of the waters, conforming In 
slope to the pitch of the surface on which they were spread out. 
The first and second of these ways have little probability 1n 
their favor. The others I make the chief source of the result 
in my memoir on the New Haven region, saying (p. 99) after re- 
marks on each method: “That part of the rapidity of slope in 
the lower portion of the plain below 40 feet in height 1s due 
to tidal, wave and river action over the region of the bay; and 
part to increasing depth over the borders of the bay southward 
and a decrease southward in the amount of transported sand. 
How far these methods are sufficient may be better considered 
after a survey of the facts from other parts of Southern New 
England. 
on the opposite side of the river.* These places are situatt 
. * For this altitude I am indebted to eooapiar empire So roms ma agg 
irmi surveyor. The leveling was made at ton, and ga 
pat raeg toce- Mr. Brinsmade states that 
height of the plain above low-water 106-64 feet. um 
some points wi to eight feet above this. ave taken as the maxim 
height of the terrace 112 feet. The height of flood-level above low water aoe 
17 feet ; is su 112 gives 95 fi the height a 
or . flood, in 1857, when 
Fiver rose to 22 feet 3 inches. 
