MODIFIED DRIFT ALONG CONTOOCOOK RIVER. I05 



turns abruptly from a northward to an eastward course, enclosing a pond 

 in the triangular hollow between it and the adjoining ridge. A short dis- 

 tance to the north is a hill, about 90 feet above the river, which appears 

 to consist of till overlaid by a gravel deposit. This is surrounded by low 

 alluvium. A little farther north the river flows at the eastern foot of a 

 gravel ridge, which is about 40 feet in height, A boulder six feet in di- 

 ameter was noticed in this ridge ; but such blocks are very rare in these 

 kames, and were nowhere seen in the high gravel deposits farther south. 



One mile east from Noone's mill, sand dunes occur on the hillside at a 

 height of about 200 feet above the river, covering some two acres, which 

 are almost destitute of vegetation. 



The Contoocook, at the mouth of Nubanusit river in Peterborough 

 village, is 734 feet above the sea. Here till and ledge rise steeply on 

 the east side, which has no modified drift. Half a mile to the north a 

 considerable width on this side is occupied by alluvial sand and fine 

 gravel, which extend in irregular slopes to 100 feet above the river, rarely 

 showing any steeply-terraced or level-topped surface. The most irregu- 

 lar portion of this area is at the cemetery, which is diversified by kame- 

 like mounds and ridges. As we approach North Peterborough the till 

 and ledge again reach to the river. Along this distance on the west 

 side, similar sand and gravel, in irregular slopes, thinly cover the hills to 

 a height of 100 to 150 feet above the river. Occasional boulders are 

 found enclosed in these deposits. 



At North Peterborough a broad, terrace-like ridge of sand extends half 

 a mile on the north-west side of the river. This has steep slopes, but its 

 top is nearly level, with a height about 100 feet above the river, being at 

 the south 820 and at the north 810 feet above the sea. The valley here 

 bends for a short distance to the east, so that to one following the river 

 northward this ridge at first appears to lie as a barrier before it. With 

 this huge sand-bank the high deposits of modified drift, which we have 

 found bordering this river continuously for five miles, come to a sudden 

 end. 



Half a mile eastward a small terrace, about 50 feet above the river, 



lies on its east side. Excepting this, we find in the next two miles only 



low alluvium, which averages a half mile in width, lying mostly on the 



east side of the river, with a height of 10 to 30 feet above it. Beyond 



VOL. in. 14 



