'Transactions of the Bombay Geographical Society, from September 1850 to June 1852. Edited by the Secretary. Volume X.' [‎223] (356/458)

KUNKUH, OR FRESH WATER LIMESTONE.
223
of toJ
to
,n poranewis
wizontal layers al t
> r t' These noW
eins of calcareoiis!;
eous spar (carbl
ia are surroaoltl
entral parts; Mllj
cavities areliiili
grey color, eitl
yellowish wllsd
i clay is identicalr-
te of lime wilt i
nd the nahiraltut'
r thesaffleff® 1
otmeantoco^'
icretioDSofth®^
itheanaW^
of the Isle of Wight, in which Mr. Webster* informs us both the nodular and
the flat form of concretionary limestone are met with ; but l would now proceed to
offer a few remarks on the probable origin of these substances.
“ The forms effected by the nodules of kunkur, and the circumstances of their
dispositions in the clayey beds with which they are associated, have frequently
been recorded by observers as being strikingly similar to those of the flints in the
chalk strata, and it was these analogies which first led me to suspect that the
information we possess concerning the origin of the one might be made to bear
upon that of the other. From the state in which the fossils of the chalk strata are
found, many of them perfect iu their most delicate details, some of the shells
preserving even their fine pearly lustre, and the soft scales of fishes being often
found beautifully preserved in the structure of flints, we are warranted in conclud
ing that they were quietly entombed near the spots where they lived and died, aud
that consequently no transport ing power of energy sufficient to bear from a distance
the associated masses of flint could have been iu action upon them. We are thug
led to believe the flint contemporaneous, or nearly so, in its origin with the chalk in
which it is imbedded, and as the flint occasionally passes imperceptibly into the
chalk, the nodules of the one near the line of junction being replaced by those of
the other, there is thus afforded an additional argument for the flints having been
formed in the places where they are now found, and against their having been
derived either from silicious springs, or other sources, and brought from a distance.
In like manner the flints which are found ia the lower beds of the great gypsum
formation of the Paris basin pass gradually and imperceptibly into the gypsum
itself 5 a proof, (says Professor Jameson in allusion to this fact) of the contem.
poraneous origin of the two substances.f Similarly the peculiarly perfect and
beautiful state of preservation iu which the fossils of the London clay are found,
would lead us to infer the quiet and contemporaneous formation of the horizontal
beds of nodular limestone with which they are associated ; and in truth this is put
beyond a doubt from the circumstance that the Septaria have frequently been found
to include fossils similar to those occurring iu the body of the clay. From these
analogous cases, and the consideration of others, I have thought it unnecessary to
detail, I have been led to consider the Indian kunkur beds as being formations
* in situ/ and nearly contemporaneous iu their origin with the beds of calcareous
clay with which they are associated. This remark applies to the kunkurs of those
localities where no proofs of the previous existence or operation of calcareous springs
can be detected, and where the facts oppose the idea of transporting forces having
been in action. 5 ’
The preceding is taken entire from an excellent paper on the Deltas of the
Ganges, prepared by Captain Smith in the first volumn of the Calcutta Journal
°f Natural History.
# Geological Trans, vol. ii* p* 209.
t Cuvier’s Theory of the Earth. English edition^