'Transactions of the Bombay Geographical Society, from September 1850 to June 1852. Edited by the Secretary. Volume X.' [‎182] (315/458)

182
GEOLOGY OF BOMBAY.
. hont a f 00 f or so below higb-water mart. It generally abounds with the
roots of the mangrove, obviously still reman.mg m the j.osd.on where
thevrrrew the fragments of the stem stand some umhes above the clay.
T have never been able to find any rema.ns of them m the concrete
above The hue and substance of the wood is m some cases but little
changed the fibres are still tough, their colour red, and somewhat
more dark than that of mahogany. For the most part however, the
roots are cemented into a black, softisb peaty matter winch crumble,
in the hand : it cracks in drying, and when dry is brittle and lusirous,
like coal. It burns without eitiier flame or smoke : long exposed in
the damp it first becomes coated with a thin film of sulphur, its cracks
being occasionally filled with pyriteons matter. Occasionally it
becomes covered over with beautiful greenish wlute speculse of sulphate
of iron This salt is so abundant in the lignite beds near Quilon as
to be collected and made use of for the purposes of the dyer. The
clay is full of nodular masses of greyish coloured limestone, from the
size of a pellet of small shot to that of the hand,—-a variety of the
substance called kunkur, which prevails all over India, and furnishes
the bulk of the mortar used in building* The kunkur of the blue
clav formation is remarkable for the extraordinary resemblance its
nodules bear in point of form to common chalk flints ; a resemblance so
*triking that but for a slight difference in point of tint, the most prac
tised eye could not discriminate betwixt them.
30, The Mangrove roots are full of perforations, obviously made
by some marine worm : they vary from the thickness of a goose-quill
to that of the thumb.
Various forms of nodules of Kunkur from the blue clay beds:—resemble c
flints in form, and form excellent water.cement.
* For a description of Knnkur, see Note Ct at the ead.