1 52 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 40 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 



