II2 SURFACE GEOLOGY. 
Half a mile south-west from these ridges, on the south side of the 
river, we find a remarkable kame, half a mile long, with a course a little 
to the east of south, composed of sandy gravel, with pebbles frequently 
six to eight inches, but not commonly exceeding one foot in diameter. 
This forms a steep ridge about 100 feet above the hollow which separates 
it from a high hill an eighth of a mile west, and 125 feet above the low 
alluvium, which extends two thirds of a mile wide on the east. A small 
pond lies in this alluvium at the foot of the kame. The next third of a 
mile south shows no ridge, but it is succeeded by a very interesting mo- 
raine, which forms a steep and narrow crescent-shaped ridge, fully half 
a mile long, lying in a similar position with the kame between the hills 
and the low alluvial area. Its course is to the south-east and east, with 
height descending from about 75 to less than 50 feet above the alluvium, 
and it is separated from the hills by a hollow nearly as deep. The crest 
of this moraine consists almost entirely of angular boulders of all sizes 
up to ten feet in diameter, which cover the surface and are piled as 
thickly as possible, with scarcely any space for finer material. On the 
sides, and along the top near the east end of the ridge, we find earth and 
boulders intermixed in the ordinary proportions of the coarse upper till. 
These blocks are principally of two kinds, derived from the Lake and 
porphyritic gneiss, which occupy the whole country for more than ten 
miles to the north. The New Hampshire Central Railroad, now discon- 
tinued, was built in the hollow on the south-west side of both kame and 
moraine. 
A noticeable feature of the Contoocook basin is, that its east and south- 
east water-shed is formed by high, irregular hills near the river, which 
has no large tributaries from this side. The lowest points of this 
water-shed usually exceed 400 feet above the river; but one or two 
miles south-east from this moraine the railroad found a line of depres- 
sion only 150 feet above the river, or 537 feet above the sea. On each 
side high hills border this pass, which connects the Contoocook valley 
with that of the north branch of the Piscataquog river. No extensive 
or remarkable deposits of modified drift were seen in a hasty journey 
along the latter valley. 
A third of a mile above West Hopkinton the Contoocook river flows 
between slopes of till 75 feet in height, and so.steep as to suggest that 
