'Transactions of the Bombay Geographical Society, from September 1850 to June 1852. Edited by the Secretary. Volume X.' [‎221] (354/458)

KUNKUR, OR FRESH WATER LIMESTONE.
221
cements for building purposes is obtained. It is occasionally found in extensive
beds in the form of solid and continuous rock, and in this shape it is excavated for
pavements in slabs and blocks from the bed of the Jumna,* in the form of what
Captain Abbott calls confluent Kunkur.f It appears in extensive fields from one
to five feet in thickness, generally very rugged and porous; it is occasionally
separated into compact masses of a hundred solid feet or more. In this shape it is
found below Allahabad in the alluvium of the Ganges. Near Benares it appears
as a shell limestone—that is quantities of recent fresh-water shells are cemented
together by kunkiferous matter into a sort of rock. This varies from one to two
inches in thickness, and covers an area from fifteen to twenty miles in extent each
way : it is from twelve to twenty feet under the surface, and is supposed to mark
the basin of a former lake r J and under similar circumstances and position, though
on a smaller scale, and apparently due to a like origin, it is met with near Poona,
in the Deccan. “The older Kunkur,” says Newbold, (Journal London Assiatic
Society) “is usually of a light brownish, dirty cream, reddish, or cancerous grey
tint; sometimes compact and massive in structure, but more frequently either
of a nodular, tufaceous, pisiform, botryoidal, or cauliflower-like form
Its interior is sometimes cancellar, or slightly vesicular ; but compact or concentric
in the pisiform and nodular varieties. Its interior structure is rarely radiated.
When compact it resembles the older travertines of Rome and Auvergne.
It aggregates in horizontal overlying masses, usually intermingled with th©
soil without much appearance of stratification. It is broken up, and used as a
rough building stone in the bunds of tanks, walls of inclosures, &c., by the natives,
and is universally employed to burn into lime*
A specimen of kunkur, analysed by the late Mr. J. Prinsep, yielded, Water of
absorption, 1 4, Carbonate of lime, 72 0, Carbonate of magnesia, 0 4, Silex 15 2
Alumina and oxide of iron, 110, 100.0
Some varieties contain so much silex as to give fire with steel : others are
almost entirely composed of earthy white carbonate of lime and crumble between
the fingersI have already described in the text the aspect generally assumed
by the Kunkur of the marine blue clay, which so strikingly resembles the nodules
of chalk-flint in its form and exterior aspect—to this the reader is referred. The
Kunkur at Ghazeepore says Capt. Baird Smith from whom the following is taken
is described by the Rev. Mr, Everest as resembling much in the
shapes it affects, the flints of the chalk strata. The bank of the river (the
Ganges) shews a section of a layer about four feet thick, formed of these
pieces. This layer is gradually lost in the clay above and below. In some
places the layer or seam is double, with an intervening bed of clay, through which
the lower kunkur bed is said to branch off and join the higher. The beds are
* Prinsep. Bl. As. Trans. 1833, vol. ii. 625.
t Capt. Abbott Bl. As. Trans. 1845, vol. xv. p. 442.
t Captain Sherewell.—Bl, As, Trans, 1846, voi. xx, p, 14,