PHYSICAL ASPECTS 363
alluvium in the valley of the Purna. The groups represented in Berar
can be tabulated thus:-
Alluvium . . . Recent and pleistocene.
Deccan trap . Upper Cretaceous or lower eocene.
Lameta . . Upper Cretaceous.
Gondwiana . . Permo-carboniferous to Jurassic.
Purina . . Pre-Cambrian.
The old rocks of the Purana group come to the surface on the south-
eastern margin of the great cap of Deccan trap, occupying the border
out to the main boundary of the Gondwana strata. They are covered
by two small isolated patches of Deccan trap-outliers south-east of
Kayar-and with some outliers of Gondwana beds in the Vaidarbha
valley and farther west. In one or two small hills in this corner of the
province the distinction between the Purana sandstones and the much
later sandstones belonging to the Kamptee division of the Gondwana
system is seen. Yanak hill (1,005 feet) is formed of Purana sandstones,
and several bands of conglomerate occur containing pebbles of hematite,
from which the iron ore formerly made at Yanak was obtained. Shales,
slates, and limestones of the Purana group prevail to the west of the
sandstone bed in Wun District, giving some magnificent sections in the
Penganga and its tributaries.
The Gondwana rocks are especially worthy of notice, on account of
their coal-measures. It has been estimated that about 2,100,000,000
tons of coal are available in Wtn District. Direct evidence of the
occurrence of coal has been obtained throughout 13 miles of country
from Win to Papfir, and for Io miles from Junara to Chincholi. It is
estimated that there are I50,ooo,ooo tons above the 500 feet level
between Junara and Chincholi: and the existence of thick coal has
been proved in the Barakars which crop out near the Wardha river, in
the south-eastern part of Wun District.
The Deccan trap, with which the greater part of Berar is covered,
was erupted towards the end of Cretaceous times, the volcanic activity
stretching on, probably, into the beginning of the Tertiary period. At
the base, and stretching beyond the fringe, of the Deccan trap, there
is often a fresh-water, or subaerial, formation, composed of clays, sand-
stones, and limestones, representing the materials formed by weathering
or actually deposited in water on the old continent over which the
Deccan lava flows spread.
The hollow containing the lake of Lonar in Buldana District was
probably caused by a violent gaseous explosion long after the eruption
of the Deccan trap, and in comparatively recent times.
An interesting feature of the alluvial deposits in the valley of the
Purna is the occurrence of salt in some of the beds at a little depth
below the surface. Wells used formerly to be sunk on both sides of