20 SURFACE GEOLOGY. 
Connecticut Lake to West Stewartstown. For the first four miles below 
Connecticut lake the river has a rapid descent, with a southerly course. 
It then bends to the west, and winds with a sluggish current through a 
narrow swamp three miles in length, which is the first alluvium seen on 
the river. Its lower end is at the mouth of Deadwater stream. One 
half mile farther down, at the outlet from Back lake, the road passes over 
a sand and gravel plain 30 feet above the river. This is material de- 
posited in the Champlain period by the tributary stream. Much of it has 
been excavated during the terrace period; and till extends to the river 
on the opposite side in a very gentle, regular slope. 
On Indian stream there is a large extent of low alluvial land, com- 
prising several valuable farms. This consists mainly of a wide interval, 
from 10 to 15 feet high, which is bordered on the east by a narrow 
lateral terrace from 30 to 40 feet above the river. In the next four 
miles scarcely anything but glacial drift and ledges is found. The 
scanty portions which may be called modified drift consist of very coarse, 
somewhat water-worn gravel, in terraces from 10 to 40 feet above the 
river, which has probably in many places cut its channel to this depth 
through the till, About the mouth of Bishop’s brook considerable low 
alluvium occurs, partly brought by the main river and partly by its 
tributary. Thence we have a narrow width of modified drift on the 
north side of the river to Hall’s stream, which is bordered by an inter- 
val from 5 to 10 feet, and two terraces, 20 and 35 feet, above the 
river. On the south side here, and on both sides for nearly two miles 
below, the river is closely bordered by hills, and no modified drift is seen. 
The portion of the river which we have now described extends south- 
westerly about eighteen miles from the mouth of Connecticut lake. The 
descent in this distance is 583 feet. High wooded hills border the valley, 
which is destitute of modified drift for half of the way. The largest allu- 
vial area is on Indian stream; and the highest terraces are from 30 to 40 
feet above the river. 
Upper Connecticut Valley. Below West Stewartstown the course of the 
river is southerly, having a descent in nearly fifty miles, to the head of 
Fifteen-miles falls in Dalton, of only 205 feet, one half of which takes 
place in nine miles between Columbia bridge and North Stratford. Along 
this whole distance the modified drift is continuous, and, including both 
