42 FERRUGINOUS CONGLOMERATE. 
or a dark-colpured rich earth, according to particular lo 
calities. 
It is obvious how the table-summits of the larger hills 
y^t remain of great extent. Though at first exposed to the 
same decomposing action as the sloping strata, this could 
only go on for a short time. The surface of the rock suf- 
fering decomposition, plants of various sorts would take 
root, and grow and bind together the new soil ; and shrubs 
and trees by degrees shooting out, would add to the effect 
of the herbage by affording a shade, and in so far obviate 
the influence of the sun''s rays, in contributing to the pro- 
cess of disintegration. A deep jungle being in process of 
time produced, no farther changes would occur in the sub- 
jacent rock, excepting in its perpendicular faces, where the 
ialternations of seasons might occasion fragments to be de- 
tached and precipitated to the plain below, or the descend- 
ing water, in the rainy months, might wear out channels in 
the surface, and carry the sand to the bottom of the hill. 
The ferruginous conglomerated gravel and sand met 
with here is entirely a secondary production, and the 
process by whick it is formed resembles, in some re- 
spects, that of the calcareous Kunkur, to be afterwards 
described, It appears to be decomposed sandstone, unit- 
ed again by means of iron, in a low state of oxidation : 
I am also disposed to believe, that the iron has been deriv- 
ed, not from a mineral, but from a vegetable source ; that 
it is, in fact, the product of decomposed ligneous fibres, 
which chemical analysis shows to contain a portion of this 
metal. The successive decay and production of vegetable 
matter would in time accumulate ; the iron and the acid- 
water, also formed by the decomposition of vegetables, in 
the rain, would in part dissolve it, and impregnate the sand 
over which it rested. Evaporation taking place, on the ac- 
