J. D. Dana—The flood from the melting Glacier. 181 
Such opportunities are not often to be met with, since it re- 
quires an exposed section of the stratified drift of a valley—an 
one recently a since the surface soon becomes concealed 
by slides down the slope. Moreover, in the narrower valleys 
of rather rapid descent, the waters were so tumultuous at all 
times that stony beds were thrown in at all levels. Ten miles 
west of New Haven, in the upper terrace of the Housatonic river, 
90 feet in height above the flood level in the river, the upper 
stratum, for twenty to thirty feet in depth, is very coarse 
stony, and mostly sandy with finer stony beds below; and the 
top of a lower terrace is still coarser in its stones. I have ob- 
hale of the formation, so far as in view, was of stones—that is 
the upper three- fourths, the lower part being concealed by the 
fallen gravel. Half way to the river along the section, irregu- 
lar Ueeiny of sand beds, two or three yards i in length were in- 
cluded among the irregular stony layers, after the she repre- 
sented in fig. 4, (p. 178). Thus the flood-torn stony features of 
the formation increase toward the river; and some of the sands 
of the uprooted sand beds were left in patches among the stones. 
To interpret the facts we have to note that the Thames is a wide 
and deep tidal estuary, or rather fiord, fifteen miles long; that, 
therefore, thereis no seaward slope to make rapid currents. The 
earlier drift de — should hence have been of the finer kind, 
a cataract, to have roduced, a along such an estuary, so extensive 
erosions and cobble-stone deposits. Although I vag i no 
other good section, I think it safe to say, judging from the 
stones which had fallen from some of the ia ers, be = for- 
mation, for at least half a dozen miles north of Groton (the 
* “— section in this part showed cay ae feet of the underlying sand str 
stratum. 
Fifteen yards nearer the river these four feet consisted of i mes and gravel 
instead of sand, being part of the sony roi alluded to abo 
