'Transactions of the Bombay Geographical Society, from September 1850 to June 1852. Edited by the Secretary. Volume X.' [‎290] (423/458)

290
CAPTAIN G. WINGATE.
The hard sandstone of Mai wan and the neighbourhood of the
Phonda Ghaut, will be found equally converted into laterite, as the
more decomposable traps; but the character of the resulting formation
is different. It is heavy and gritty, instead of being earthy like the
trap-laterite,—being in fact full of grains of undecomposed quartz;
but its sinuous cavities and red color are much the same. Above the
Ghauts trap-laterite and metamorphic schist-laterite are common^
the latter generally hard and heavy, with a large proportion of iron ;
and syenite-laterite is, if I mistake not, to be met with at Vingorla.
Many examples of trap passing into laterite may be found among
the stones lying about the travellers’ bungalow at the top of the
Phoonda Ghaut, and a geologist proceeding from Viziadroog by
this route to Belgaon and Dharwar, would have an opportunity of
seeing most of the varieties of laterite I have mentioned, without
having occasion to leave the high road for more than fifty yards in the
whole distance.
The decomposition by which I suppose the transformation into la?
terite to be effected, does not appear always to proceed in the same way,
I have met with several specimens of trap converted into homogeneous
yellow earth, without any indication of sinuous cavities. Again, the
cavities appear in other instances first, as in the pitting of the surfaces
of hard and soft traps and sandstones already noticed as so common.
I have further found on breaking some hard trap nodules of a granular
texture, and which externally appeared perfectly sound, that the
fractured surface was dotted over with small white specks, which in
some instances were enlarged into small cellular cavities filled with
a brownish or yellowish earth, which as the process of decay goes on,
may be easily supposed to become receptacles for water, and gradually
to join each other until they become enlarged into the sinuous cavities
characteristic of the laterite.
I conclude by recapitulating the chief facts that occur to me in
favor of the hypothesis of the laterite being a rock transformed in-situ
by the action of causes still in operation. These are—1st, the invariable
superficiality of the rock. 2nd, The ordinary limitation of its occurrence
to regions subject to heavy and long continued rains, by which the su
perficial rocks are rapidly decomposed, especially in the immediate