106 SURFACE GEOLOGY. 
this we find the valley for the next six miles, extending nearly to An- 
trim, well-nigh destitute of any alluvial or terraced deposits; yet it has 
along most of the way an ample width with gently sloping sides, which 
are usually the conditions for the accumulation of extensive plains. In 
this distance, and for several miles farther north, the descent of the river 
is small, amounting to 123 feet in the sixteen miles between North Peter- 
borough and Hillsborough Bridge. More than half of this occurs at Ben- 
nington, where its fall is from 676 to 606 feet above the sea; for the rest, 
the average slope is about three feet to a mile. 
The only important deposits of modified drift seen along this river for 
six miles were kames, which appear on the east side near the north line 
of Peterborough, and are very well shown upon both sides of the valley 
at one mile south-east and south-west from Bennington. In the north 
edge of Peterborough these consist of sand or fine gravel, which lie in 
numerous mounds and ridges, in depths to 20 or 30 feet, upon a sloping 
hillside of till go to 100 feet above the river. These deposits are irregu- 
larly stratified, conformably in some places, and perhaps generally, to the 
underlying surface. They contain here and there embedded boulders, 
the largest of which observed was four feet in diameter. 
From a half mile to more than a mile south of Bennington, on both 
sides, we have large accumulations of kames. On the west they rise to 
about 140 feet above the river, and consist of sand in hillocks and north 
and south ridges, which are 50 to 75 feet in height, lying on till. In the 
sand, which is irregularly stratified as seen in many places, there also 
occur occasional boulders up to four feet in size. On the east side these 
ridges and banks are well shown along the road to Greenfield before 
coming to Whittemore pond. They are composed in large part of the 
‘coarse, water-worn gravel which is characteristic of the kames, inter- 
stratified with sand, and containing embedded boulders. These deposits 
reach a height fully 175 feet above the river, or 850 feet above the sea. 
Thence to the south-west similar deposits border the north and west 
sides of the hills to within a half mile of Pollard pond, being well shown 
on the east side of the Manchester & Keene Railroad, now being built, 
for one mile south from Bennington station. Here they form nearly 
level terrace-like banks of fine gravel or sand, 170 to 175 feet above the 
tiver, irregularly stratified and rarely containing boulders, 
