boundary, and the Dwarkeswar or Dhalkisor, which traverses the centre
of the District. They are insignificant streams during the hot season,
but in the rains become navigable by boats of 50 to 60 tons burden.
During this season they sometimes rise so suddenly, owing to the
rapid drainage from the neighbouring hills, that a head wave is formed,
called the hurpa ban, not unlike the bore or tidal wave in the Hooghly,
which often causes loss of life and great destruction of property.
The Silai and Kgsai cross the south of the District.
Gneiss appears in the western hills, especially in the neighbourhood
of Bankura town; and in the north-west metamorphic rocks stand up
boldly in well-marked hornblendic ridges, the general strike of which
is nearly east and west. South of Bankura town veins of granite occur,
especially in the metamorphic rocks along the Silai river, cutting through
the gneissic rocks. The Gondwana system is represented in the north,
on the banks of the Damodar river, by beds which belong to the
Raniganj group and may contain useful seams of coal. Elsewhere the
surface consists of gently undulating ground, covered by laterite and
alluvium. The former is invariably detrital, and contains such quantities
of quartz pebbles as to resemble a coarse ferruginous conglomerate.
The laterite is extensively overlaid by a sandy clay, which is often
intermixed with kankar'.
The uplands are bare or clothed with a scrub jungle of Zizyphus and
other thorny shrubs, which sometimes gives way to sal (Shorea robusta)
forest, while the low hills are covered by a dense mixed forest, which
contains species of MAiliusa, Schrebera, Schleichera, and Diospyros. In
the low-lying land to the east, the swamp vegetation of the West Bengal
rice plain is found. In the neighbourhood of villages are thickets, in
which the most common species are bamboos, pipal (Ficus religiosa),
banyan (Ficus indica), red cotton-tree (Bombax malabaricum), Mangi-
fera, Moringa, and Odina lodier. The District contains no Govern.
Black bears are common in the western jungles; and hyenas, leopards,
wolves, deer, and wild hog are also occasionally found. Pythons are
often met with in the hills, while the cobra, karait, and other deadly
snakes are common.
Exceptionally high day temperatures are a feature of the hot months,
the mean maximum rising to 93° in March and o02° in April. The
mean temperature for the year is 80°. The annual rainfall averages
56 inches, of which 10.4 inches fall in June, 12.7 in July, 12.4 in
August, and 8.2 in September.
Memoirs, Geological Survey of India, vol. i, pt. iii, ' The Geological Structure
and Physical Features of the Districts of Bankura, Midnapore, and Orissa'; also
vol. iii, pt. i, 'The Raniganj Coalfield,' by W. T. Blanford. This section was
supplied by Mr. P. N. Bose, of the Geological Survey of India.