during the melting of the Glacier. 413 
servations needed to settle all doubtful points demand long- 
continued investigation in each estuary region of the coast, such 
a study as can be satisfactorily carried forward only by one 
who is living in the region and is thus always at hand to take 
advantage of every excavation that may be made in the deposits 
for cellars or other purposes. And to this should be added 
an accurate topographical and hydrographic survey of the estu- 
_ ary regions, and of the river valleys within thirty miles of the 
oast 
st. 
After these preliminary considerations I proceed to the dis- 
cussion of the facts bearing on the level of Southern New Eng- 
land in the Champlain period, or, its equivalent, the amount of 
elevation which may be proved, from existing conditions, to 
have taken place since that period. 
I. New Haven REeion. 
The evidence with regird to the amount of depression over 
the New Haven region which has been obtained is from the fol- 
lowing sources : 
_1. From the height of the upper or highest terrace of a re- 
gion above mean high tide. 
2. From the depth of the valley-excavations along the rivers 
and estuaries, or the height of the upper terrace above the flood- 
plain of the present streams, 
3. From the structure of the beds 
