412 J. D. Dana—Depression of Southern New England 
region may be only one or more of the lower terraces instead of 
the highest; that is, in other words, the A7ghest normal to the 
region may be wanting, either (1) because there the flood-waters 
made no depositions up to flood-level, owing to its fierce rate 
of flow, or some other cause, but built up only to lower levels; 
or (2) because the highest part of the formation, after its depo- 
sition, was swept off and so reduced to a lower level by the flood 
when in its period of greatest violence, leaving only a lower 
terrace in its place, with perhaps traces of the higher, or often, 
not even these. 
6. A careful study of the kind of stratification in the de- 
posits is needed in order to determine whether the beds were 
deposited (1) under the action of the incoming tide on the sands 
and gravel from the dissolving glacier or drift-covered hills; 
or (2) under the action’ of the outflowing river. This study 
requires that the cuttings for all road-gradings, wells, sewers, 
and cellars, in the stratified drift of an estuary, should be care- 
fully examined. When the facts as to structure are fully under- 
stood, the question whether sea-made or river-made may 10 this 
way receive a positive answer even along shores having 20 
raised shell-bearing sea-beaches. ; 
. An examination should be made for stratified deposits of 
the later or “ Alluvian” part of the Champlain period, and @ 
comparison of the heights of such beds with that of the early 
Champlain beds or true “ Diluvian” stratified drift ; for suc 
beds may show at what level the waters of an estuary or inlet 
stood after the Glacial flood had for the most part or wholly 
subsided. 
The mere statement of these points is sufficient to fe 
that the problem before us—that of determining the amount 0 
depression of Southern New England during the Champlain 
pared or, of elevation since then—is beset with difficulties 
‘These difficulties I have not been able in all respects to co 
_ mount; and my present purpose is to state the facts which 
have observed, and not to announce positive results. The o 
