through the Farmington valley to New Haven Bay. 445 
The profile and the tables with the other observed facts make 
manifest : 
First. The fact of the Quinnipiac dam, as already explained ; 
the first table showing a gradual decline in the heights of the 
upper-terrace level from Southington through Cheshire; and 
the second, the continuation of the high-level Quinnipiac terrace 
of Southington to Hough’s Mills, or 44 miles, where the terrace 
has a height of 200 feet and is one and the same with that o 
Mill River; then a drop down of 95 feet, the terrace just above 
the head of Hanover Pond having a height of.only 105 feet 
above mean tide, and but 19 feet above low water in the 
stream, * 
tinued on as the upper, with gradual slope, to New Haven Bay. 
The water-fall is indicated in the section, page 442, under the 
number 164. 
The height of the terrace two miles north of the gap is some 
indication as to flood-level at the gap. But direct evidence is 
afforded by deposits of very coarse gravel, partly cross-bedded, 
hear the top and under the lea of the western trap ledge of the 
gap ; and also (2) by the continuation of these deposits south- 
ward, many of the stones of which for the first mile are one 
to three feet in diameter, all well smoothed and none scratched ; 
and (3) by the existence of remains of a great well-smoothed 
trough or sluice-way, about 30 feet wide, in the sandstone, 
which was the work evidently of a violent torrent, several 
long oblique recesses on its sides, one to three feet broad, being 
marks of its revolving flow; the smoothed surfaces are nowhere 
8cratched, and in this and other ways show that they are not 
of glacier origin. 
The accompanying figure is a profile of the gap, with the 
height exaggerated only two times. Mt. Carmel (on the east) 
is an east-and-west ridge, chiefly of trap, 789 feet in greatest 
height above mean tide. It is the eastern portion of a range 
_ ‘The divide has a height of 185 feet above mean tide, which was ete Nek 
below the level of the flood at Hartford; and the terrace topping the 
Aa height of about 20 feet. 
