446 J. D. Dana—WDischarge of the Flooded Connecticut 
of trap and sandstone which continues westward to the West — 
Rock trap range. The gap is about 250 yards wide; but it is 
partly obstructed by ledges, and Mill River occupies only 100 
feet of its breadth. The waters of the sluice-way flowed out (at 
H) west of the summit of the western of these ledges (C); the 
lowest level over which at H is now 164 feet. The stratified 
gravel referred to as under the lea of this ledge (visible from 
the railroad cut R) has a height of about 152 feet; and the 
upper limit now visible of the excavated trough or sluice-way 
near the Mt. Carmel station, half a mile south of the gap, has 
a height of 145 feet. This trough or sluice-way in the sand- 
stone was uncovered in grading for a new lay-out of the rail- 
road, it offering the lowest level for the track. It can be traced 
along the course of the railroad for 200 yards below the station ; 
it then passes to the westward of the road and becomes the — 
head of a partly cobble-stone paved valley whose stream Joins 
Mill River at Centreville (see section). The sluice-way torrent 
must finally have worn away part of the east side of the trough 
and so made a passage into Mill River valley. The height of 
the trap at D above mean tide is about 240 feet. 
(3.) The slope of the flood-level was widely different above and 
below Farmington.—The slope of the terrace (or of flood-level) for 
the first 33 miles, that is, from Northampton to Simsbury (Sd on 
plate 5) was only 6 inches a mile; and for the first 44 miles, or to 
Farmington, about 7 inches: while southward, from Farming- 
ton toa point 2 miles north of Cheshire, where the high land 
of Cheshire begins, it was about 5 feet a mile; from the latter. 
place to the Mt. Carmel gap, about the same; and from Mt. 
Carmel village to New Haven Bay, 10 /eet a mile. A reason 
for this change in slope at Farmington exists in the fact that 
the flooded Farmington River here entered the valley from a0 
extensive region to the northwest, and the Pequabuck add : 
waters from the west; the two draining a high portion of © 
western New England about 200 square miles in area. The 
flood consequently received its greatest accessions at this point; 
and the waters were so rapidly supplied that the slope north: Se 
ward was diminished and that southward increased. On the 
west side of the valley to the north of Farmington station, the 
