I§2 SURFACE GEOLOGY. 
borders the river. In the north part of Somersworth, sand and ordinary 
gravel extend from the river to the railroad and Cole’s pond. These de- 
posits lie in irregular slopes, nowhere presenting the usual level terraces. 
Thence very coarse kame-like gravel, spread out in level plains, extends 
southward, and forms the water-shed west of this river to Willand pond. 
In the next four miles to Salmon Falls, east of these kame-like plains, 
the valley of the river consists of till or ledge. 
Below Salmon Falls the river has excavated its channel between prom- 
inent terraces, upon which the villages of South Berwick and Rollinsford 
are built. Their height is nearly the same at both sides, being about 80 
feet above the river, or 100 feet above the sea. The same terrace-plain 
extends west to Rollinsford junction, where its height is 115 feet above 
the sea. The last mile and a half of this river is bordered on both sides 
by level plains about 4o feet in height. On the west these are a half 
mile wide, terminating in Rollinsford point. 
Cochecho River. The water-shed between Winnipiseogee lake and this 
river is composed of modified drift (p. 130), which is very scanty or want- 
ing along the next four miles to Farmington. Three streams, which are 
the head waters of this river, have here brought down large amounts of 
gravel and sand, forming the low and partly level area west of Farming- 
ton village. Below this place the modified drift, lying principally in 
kames, or irregular mounds and ridges, is continuous on both sides of 
the river, being one half to three fourths of a mile wide for five miles, 
beyond which it expands into the extensive plains of Rochester. These 
mounds and ridges rise from 20 to 30 feet above the intervening hollows, 
reaching a height about 50 feet above the river. Their material is coarse, 
water-worn gravel, with occasional layers of sand; and sections usually 
show an anticlinal or arched stratification. A half mile east of Farm- 
ington these kames enclose numerous bowl-shaped depressions, some of 
which contain small ponds. This part of the Cochecho valley is bordered 
on both sides by hills, which rise 300 to 400 feet above the river. 
Two and a half miles above Rochester the area of modified drift widens 
on the east, reaching to Salmon Falls river (Plate VI, p. 146). Thence 
level, sandy plains, in many places underlaid by clay, extend along the 
Cochecho eight miles. The coarse kame-like gravel continues on the 
west side of the river nearly to Rochester; but the wide plains at this 
