'Transactions of the Bombay Geographical Society, from September 1850 to June 1852. Edited by the Secretary. Volume X.' [‎172] (305/458)

QSOLOQT O ® 1 BOMBAY. ; -
Mahaluximee, it often sinks down to the level of the sea, where it i*
covered over with alluvium, and is only traceable in wells, quarries, and
other excavations : it sometimes rises into knolls, sometimes into beauti
fully picturesque little hills, of above 100 feet in elevation. It varies as
much in quality as in aspect, presenting us occasionally with a nearly
black amygdaloidal green-stone,—next Parell, to the south of tliis»
fine, soft, pale-blue, earthy trap—with every variety of tuffa, amygd&.
loid, and compact green-stone^ that can be imagined.
12. —Details.—T he highest part of Cblaba is that on which
the light-house is built—it is about 55 feet above the mean level
of the tide. From this the surface descends on both sides to the
sea, sloping gradually to the N.E., in a line with the axis of the island.
The trap here* as everywhere along our shores, is covered* at from
six to ten feet above high-water mark, with sea gravel, loose or
cemented. For upwards of a mile to the south-east, east, and west-
ward, filling up a large space on the harbour side* and the bulk
of the area of Back Bay, the trap is covered by the tide. The line of
junction betwixt the basalt of Malabar Hill, and the greenstone of
Back Bay, is lost under water: it is probable, from the aspect of
the cliff, and the depth of water near its base, that a mass of softish
stratified rock, through which the principal channel has been grooved,
interposes itself betwixt them all the way along. Opposite the Marine
lines there is a large mass of well formed columns of basalt, which just
show themselves above low water—apparently beneath the fresh water
strata at the base of Malabar hill,—-becoming tuffaceous near the line of
junction as if erupted from beneath, after the deposit of the alluvium
now above them.
13. ^ About a mile and a half from the lighthouse towards the For( r
near the site of the Cabool Church, a mass of stratified rock makes its
appearance on the harbour side of the island, showing itself along the
sea shore near the Pilot’s pier, and being pierced by the well near the
Church : it does not quite cross the island, the green-stone re-appearing
on the Back Bay side. Towards the Jamsetjee Break-water and
Cotton-screws the rock becomes amygdaloidal, and presents us with
a considerable variety of minerals. At the velard it seems much
disturbed* the stratified and trappean rocks being mixed up together I
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