'Transactions of the Bombay Geographical Society, from September 1850 to June 1852. Edited by the Secretary. Volume X.' [‎190] (323/458)

190
GEOLOGY OF BOMBAY.
extending several feet into the ground,—the earth where freshly excavat
ed presenting in many cases a glossy striated appearance in the walls of
the fissures. I have never met in these beds with any fragments of
wood or other vegetable matter, truly belonging to them, and they are
nearly devoid of all organic remains. I felt at a loss whether to assume
it to be of marine or lacustine origin, when the excavation of a large
tank near the Bailway, betwixt the Bishop’s house and the Byculla
Schools, solved the difficulty. The surface here, as estimated by the
line of the railway, is twenty feet above the level of the sea—at least
eight feet higher than the most elevated of the newer marine forma
tion. Six feet under this the yellow earth was found to abound with
nodules of kunkur, of a hard arenaceous semi-crystalline texture; a
piece of the shell of the thin paper or pearl oyster formed the nucleus
of each nodule: the shells where not protected by an encrustation of
kunkur, had all apparently been dissolved out. This solved the question ;
the lower alluvium had originally been a marine deposit,—blue clay, or
silt most probably,—which on being elevated and long exposed to the
air and rain, had had the marine remains, and probably the original flint
like nodules of kunkur, dissolved out of it. Common oyster and other
shells were afterwards found in fragments, but not in such numbers
as to enable the age of the formation to be determined. The kunkur
with which the lower alluvium abounds, is of a somewhat paler
tint than the soil itself : it is the same in point of external appearance
as that generally prevalent in the interior, and bears no resemblance
whatever to the smooth and fantastically shaped nodules found in the
blue clay. It is rough and amorphous, often runs out into long
branches like coral, and has always a fibre of grass, or some other
vegetable, shell, or mineral substance, in the centre—the primiary
nucleus, around which the lime had originally deposited itself. Io the
absence of woody matter the peculiar form of the kunkur and aspect of
the soil itself makes this readily distinguishable from the formations
just over it; though, if it was, as I have assumed, originally a marine
formation, the cause of these differences is not easily explained. It h
probable, at the same time, that the nodular kunkur found in the salt
clay may by long exposure to the aetionof fresh water have been redissol
ved, and the lime contained in it a second time thrown down in the
form in which it is now found, The lower alluvium forms the soil of
Him Road, an
(lie level of the
I, furnishing a
lie occurred sir
liiximee and Lov
nldseem, hav
t-Lall Mu\
ceiling formation
lie natives. Th
«tli, in contrao
H and the m
itely applied i
ik is too har
it seems unforti