'Transactions of the Bombay Geographical Society, from September 1850 to June 1852. Edited by the Secretary. Volume X.' [‎289] (422/458)

289
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rue laterite I*
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LATERITE OP THE SOUTHERN CONKAN.
position of the original trap beds, and also in some places their ob
scurely piismatic structure, so perfectly that where blackened by the
weather the rock might readily be mistaken for basalt. The original
structure of the trap is quite perfect notwithstanding the conversion
of the rock into the ordinary channelled red and yellow laterite.
The flatness of the lateritic plateaus of the Southern Conkan, I ascribe
to the horizontally of the trap beds from which they have been formed,
and the latter rock may still be seen in many places. But the
exposed edges of these trap beds, on the slopes of hills are often also
found converted into laterite, which is then spread like a sheet
or mantle over the subjacent trap beds, and may entirely conceal them
from view, as in
the marginal section,
where the laterite
covers the slopes as
well as the summit of the hill. The laterite of the slopes is
generally found to have run into an amorphous sheet, so as to obscure
all trace of the underlying strata. Unless in the immediate neighbour
hood of the coast, however, the subjacent rock is usually discoverable in
the beds of torrents which have either removed the laterite, or have
prevented its formation in the first instance. The harder kinds of trap
containing much iron, form a heavy ferruginous laterite ; and again, the
more aluminous and tufaceous varieties become a light description of
laterite. frequently with the yellow color perdominating over the
red. The most convincing proof of the conversion for which I am
arguing is to be found where it is only partially effected. An atten
tive examination of almost any locality ten miles removed from the
coast where the subjacent rocks are discoverable, will afford examples
of this. I will instance one in a nullah immediately south of the village
of Palee, about ten miles N. E. of ftutnagherrie, where a nodular trap has
the outer concentric coats of its enclosed nodules converted into
laterite, while the harder centres remain unchanged* A similar ex
ample occurs between the villages of Karrowtch and Yelloura on the
road from Bajapoor to Lanjd. And all over the Southern Conkan*
most of the detached fragments, and exposed surfaces of trap and other
rocks, will be found more or less pitted or dotted over with small holes
or cavities, which appear to indicate the commencement of the de
composing process by which the rock is converted into laterite*