MODIFIED DRIFT IN PISCATAQUA BASIN. I5I 



in width, enclosing Round pond. Except on this side, its shores are till 

 or ledge. No examination has been made between this pond and Milton 

 Mills. In the two miles from this village to Branch river, the modified 

 drift rises in irregular slopes to a height of 20 or 30 feet. 



Along Branch river the modified drift is well shown, forming swampy 

 areas and terraces of sand or gravel 20 to 40 feet in height. Kames 

 were noted in Wakefield a quarter of a mile west from Wolfeborough 

 Junction, and at several other points southward to Union village. At 

 one half mile to two miles south from this station they are finely dis- 

 played along the railroad, mostly on its west side. They are composed 

 of coarse water-worn gravel, in ridges 25 to 40 feet high, with their trend 

 generally north and south. These kames descend with the valley from 

 about 575 to 475 feet above the sea. 



The valley of Salmon Falls river in Milton contains three natural 

 ponds, through two of which the river flows. The two south-west ponds 

 lie near the east foot of Teneriffe mountain. They are bordered by 

 kames on their west and south sides; and low, sandy plains extend be- 

 tween them and the North-east pond. They are all flowed to the same 

 height by the dam at Milton Three Ponds village, which has been re- 

 cently raised a few feet, overflowing a large meadow above North-east 

 pond, and holding the river level six miles, or to within a half mile of 

 Milton Mills. Below this dam the river descends about 200 feet in the 

 next three miles, its channel lying between ledges or steep slopes of till. 



The next modified drift is in the north part of Rochester (Plate VI, 

 p. 146), where for a distance of two miles it occupies the entire area a 

 mile and a half wide between Salmon Falls and Cochecho rivers. This 

 tract is crossed by the Portsmouth, Great Falls & Conway Railroad. It 

 consists of sandy plains, 25 to 40 feet above the river, or of extensive 

 swamps and peat-bogs. The latter were scantily filled with modified 

 drift, while it was more abundantly supplied on all sides, preventing 

 drainage. Salmon Falls river here turns to the south-east. A straight 

 course would carry it southward across this area, bringing it to a junc- 

 tion with the Cochecho at Rochester. In the Champlain period the 

 highest floods of these rivers were united here, and nearly all the modi- 

 fied drift which they brought down was deposited in these plains. 



At East Rochester a narrow belt of alluvium, from 20 to 30 feet high, 



