96 J. D. Dana—The Flood of the Connecticut River Valley. 
races,” especially’ those that project out into the Connecticut 
valley so as to terrace it for some distance, may be and gener- 
ally are, the best indicators of maximum flood-level to be 
found, the true highest normal terraces; because, as already 
explained, the supply of detritus for terrace-making was there 
the greatest. Were the waters so clogged by the material 
under transportation as to flow like mud, the angle of pitch 
might be even as high as 15 or 20 degrees. But the stratified 
and straticulate structure of the deposits proves that such a 
condition was of rare occurrence. 
From this obvious relation of the tributary terraces to those of 
the main river it became of the highest importance to ascertain 
whether the “ delta-terraces ” of the different tributaries might 
be safely taken or not as the highest normal Connecticut ter- 
races for the part of the valley in which they oecur, and the 
study of this point was one of the prominent objects before me 
in my examination of the Connecticut valley. ound, in 
nearly every case investigated, that the outer part of the tribu- 
tary terraces would have been within the range of the 
waters of the Connecticut; so that, while the tributary was 
pouring in its abundant detritus, the main river would have 
feet below, is not possible, unless the side of the Connecticut 
against the mouth of the stream were blocked with solid ice; 
and this condition is shown by other facts not to have existed. 
The facts are similar in the case of the “delta-terrace ” of Israel's 
Brook in Lancaster; of Jacob’s Brook in Orford, five miles 
north of Thetford ; of Eastman’s Brook in Piermont; and of 
most other delta-terraces. 
al 
comparisons good general results can be reached. 
The range of normal upper terraces along a valley should 
have a pitch down stream corresponding in a general way wit 
that which the river had at the time of the flood. Mr. Upham’s 
Report states that the upper terrace of the Connecticut valley 
becomes suddenly lower above Thetford, where the long “ kame 
ends; is reduced at Ely, two miles above Thetford, from @ 
