THE NATURE OF LATERITE. 
257 
account of the geological position and asso- 
ciation of the laterite or iron -clay formation 
of India, with his description of the rock 
near Hurdwar, just alluded to by Dr. Benza : 
we should add by the way that, in allusion 
to the marine organic exuvise said to have 
been discovered. Dr. Benza comments 
upon the importance of inquiring into the 
existence of their fossils. Dr. Voysey was 
one of the first to mention the existence of 
marine and fresh water shells in a fossil state 
in the south of India. In 1822, Col. Cullen 
deposited in the museum of the College of 
Madras shell limestone, found in the North- 
ern Circars, forty miles from the sea-shore ; 
and Mr. Malcolmson has given an account 
of the geological position of fossil shells 
found under trap between Hydrabad and 
Nagpore. Dr. Benza says that these 
geological appearances confirm the accounts 
given in the Puranas, viz. that “ it has been 
handed down by tradition that the greatest 
part of the Coromandel Coast was sud- 
denly elevated out of the sea.” Mr. Cole 
justly considers it an opprobrium on science 
that so little is known concerning laterite — 
a mineral so extensively distributed and of so 
marked a feature in Indian geology ; and pro- 
ceeds to give a succint account of what has 
been written on this rock. Buchanan, in 
alluding to the hills of the country, mentions 
that iron ore is found forming beds, veins, or 
detached masses, in the stratum of indurated 
clay ; to this he was the first to give the name 
laterite. This is not the indurated clay of 
Kirwan, but appai*ently the argilla lapidea of 
Wallerius. It is diffused in immense masses, 
without any appearance of stratification, and 
is placed over the granite that foi'ms the 
basis of Malayala. It is full of cavities and 
pores, and contains a large quantity of iron in 
the form of red and yellow ochres. Excluded 
from the air it is soft ; when cut it becomes 
as hard as brick and resists air and water. 
It is cut into the form of bricks, being one 
of the most valuable materials for building ; 
in several of the native dialects it is called 
the brick-stone. Where, by the washing 
away of the soil and exposure to the air, it is 
hardened into a rock, its colour turas black, 
and its pores and inequalities somewhat 
resemble the skin of a person affected 
with cutaneous disorders ; hence, in the 
Tamul language it is called itch-stone. 
Dr. Buchanan, speaking of the minerals 
of Rajmahal hills, says that “ south from 
Mansahandi, at Jajpar on the borders of 
Birbhum and Murshedabad, there is a hill, 
which consists chiefly of this clay. It is a kind 
of breccia, and contains ferruginous nodules 
in an argillaceous cement, Babington, in 
his paper on the geology of the country be- 
tween Tellicherry and Madras, alludes to 
hills of a rounded form composed of the 
ferruginous stone, which he distinguishes by 
the name of Buchanan laterite. In the po- 
rous rock, the red ochiy part is the matrix, 
the kidney-shaped interstices are filled with 
white earth, alluvial formed from the wash- 
ings of the ghaut mountains. In these the 
hornblende decays into a red oxyd, and the 
felspar into porcelain earth. When this allu- 
vial rock is exposed, the white parts, says 
Babington, are washed away, and a porous 
ferruginous stone is left behind. The pri- 
mitive rocks underneath appear in many 
places above the coast midway between Cali- 
cut, Tellicherry, and Moy. Four miles in- 
land from Calicut are two low hills com- 
posed of cubic iron ore. The laterite forms 
the hills. Near Manantoddy, there is a quany 
of laterite. The rocks in Mysore decay, leav- 
ing a whitish soil beneath the surface, owing 
to the quantity of felspar they contain. The 
dark particles of hornblende become ferru- 
ginous, and this in general forms the top of the 
mountain, which is reddish. Little fragments 
become rounded, and in some cases at Banga- 
lore the whole is settled into the ferruginous 
stone. In the detritus of these rocks, it does 
not seem that particles of felspar are washed 
away until they are decomposed : water per- 
colates through the mass and carries oft’ the 
other constituents of the sienite, leaving the 
felspar in a decayed state in mass.' Voysey 
alludes to wacken passing into iron- clay and 
forming elevated table land at Beder, which is 
2,359 feet above the level of the sea. Voysey 
represents that it closely resembles that of 
