MODIFIED DRIFT ALONG CONTOOCOOK RIVER. 105 
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, III. 14 
