156 SURFACE GEOLOGY. 



formation of these deposits to the same causes which produced the 

 kames. The ice-sheet still remained unmelted upon each side at the time 

 of their deposition, filling the valleys and wide areas of low land, over 

 which this gravel and sand must otherwise have been spread by the cur- 

 rent of the floods on which they were brought. 



The most extensive of these plains occur about Willand and Barbadoes 

 ponds, near Dover, and in Newington and the north-west part of Ports- 

 mouth. Broadly rounded deposits of the same class occur frequently in 

 this district; and southward, along the sea-coast, they form the elevations 

 on which the villages of Rye, North Hampton, and Hampton are built. A 

 very interesting ridge of this kind extends from north-west to south-east 

 through Newburyport. 



Willand pond* is situated principally in Somersworth, two and a half 

 miles from the city hall in Dover. Its area is 84 acres, and its height 

 above low tide in the Cochecho is 192 feet, as determined by survey of 

 Hon. James A. Weston and Joseph B. Sawyer, made in 1871, in reference 

 to supplying the city of Dover with water.f Their report says of this 

 pond: 



"It has no visible inlet worthy of consideration, and at ordinary 

 stages it has no visible outlet. The ordinary annual high-water mark 

 was about two feet above its surface at the time the survey was made. 

 It appears that when the pond reaches this height, the surplus water, if 

 any there be, runs off through a piece of low, wet, bushy ground (called a 

 heath), of some 10 to 15 acres in extent, which lies on the northern bor- 

 der of the pond, — the water finally escaping through a slight artificial 

 channel or ditch into a brook, which is tributary to the Salmon Falls 

 river. 



" On all other sides the pond is bounded by a dry, gravelly plain, which 

 is from 12 to 17 feet above low water, and which extends from a quarter 

 to a half mile from the pond. This plain is bounded in most directions 

 by lower plains and valleys having a retentive clayey soil, which, being 

 lower than the surface of the pond, contribute nothing to its waters. 



*The plain about this pond, and the kame which extends thence to the south, are shown on Plate VI, p. 146. 



t Other heights in Dover, measured in this survey, arc the following, stated in feet above low tide in Cochecho 

 river : Lower step of front door of city hall, 45 ; do. of American House, 73 ; summit on Franklin St., near Dr. 

 Home's, 86; corner of Locust and Silver sts., 98; first floor of Belknap school-house, 123; threshold of tool-house 

 at Pine Hill cemetery, 152 ; highest point on Garrison hill, 297. 



