566    GEOLOGY OF NEW-HAMPSHIRE.

sition of the one gives a light, sandy surface—of the other, a rich,
heavy, productive soil. Hence the fertility of Vermont, and the
fact that, according to the census of 1870, she largely leads New-
Hampshire in every department of agricultural production.

The valley of the Connecticut is often mentioned as the garden of
this State. Its fertility greatly surpasses that of the Merrimack.
The alluvial deposit of limestone, worn from the scattered ledges
along the eastern border of the Connecticut valley has contributed
largely to the productive capacity of the towns along the borders
of that river, and given to Colebrook, Lancaster, Haverhill, Leba-
non and Walpole, an agricultural importance above Boscawen,
Manchester, Nashua, and the other towns bordering on the Merri-
mack.

But the granite ledges of the Merrimack valley amply compen-
sate for the thin soil of that region. In a purely limestone coun-
try the streams have worn their channels to a great depth, and
whatever falls there may have been are graded down to a plane of
descent so extended and uniform as to make any available water-
power an impossibility. The banks are also yielding and unrelia-
ble for dams. On the other hand, granite and gneiss have not only
hardness, but in New-Hampshire crop out in irregular ledges,
with their lines of stratification at right angles to the courses of
our rapidly-sloping rivers. These out-cropping ridges of the strata
running across the streams, produce pitches and sudden descents,
which, according to the steepness and volume of water, take the
form of rapids, falls or cataracts. The water powers of the Merri-
mack, Winnipisaukee, Contoocook, Suncook, and Cocheco are ref-
erable to this origin. With the adjoining banks and river-bottoms
of granite, dams can be built proof against the corrosion of under-
currents and the momentum of freshets.

SURFACE ASPECT OF NEW-HAMPSHIRE.

The southern half of this State—that portion below Lake Win-
nipisaukee—has a degree of unevenness above the undulating and
below the mountainous, to which Thoreau has given the name of
“ hilliness.” Two summits have a marked altitude and celebrity—■
Monadnock and Kearsarge.—Both attract a large number of sum-
mer visitors, and afford a magnificent view of the central portion
of New England.

The northern part of New-Hampsliire has a mountain scenery