SYNOPSIS OF PABT U. 
Ixxxvii 
and was subsequently cemented by the action of segrega- 
tive tendencies, due to the presence of some organism in 
the lake, such as one allied to Girvanella. This theory 
is only a variant of Mallet's. 
5. J. M. Maclareu, relying on a very clear section at Talevadi in 
the Belgaum district, holds that lateritic deposits are 
derived from mineralized solutions brought to the surface 
by capillarity, and are essentially replacements — mechani- 
cal or metasomatic — of soil, or of rock decomposed in situ, 
or of both. 
An actual case is then considered, namely the bauxitic lateritfc of 
the Yeruli plateau in the Satara district. The conclusion arrived at 
is that the uppermost portion of this l iteritehas been formed in the way 
supposed by Mallet, and that the underlying portions have been formed 
by the chemical alteration of the trap rocks in situ. And the point is 
emphasized that no one theory of origin can be appUed to all laterites, 
but that each case must be considered on its merits. 
In the formation of laterite manganese often seems to have been 
entirely removed. When present it does not seem to form intimate 
mixtures with the oxides of iron and alumina in the same way as these 
two do with one another ; on the other hand it nearly always appears 
as definite segregations in the ordinary laterite, although there are 
exceptions to this. Of all the many occurrences of manganese-ore in 
lateritic rocks, however, only three are in rocks that would be called 
laterite without hesitation. These are the occurrences of Goa, Talevadi 
in Belgaum, and Gosalpur in the Jabalpur district. 
The remainder of the occurrences of manganese- ore are in a rock 
that some geologists would probably designate laterite ; but others 
would probably object to the application of this term. The rock 
referred to has a lateritic aspect and usually consists of a cavernous 
mixture of various oxides of iron, chiefly hard limonite, yellow ochre, 
and soft hematite. When no other constituents are present, the rock 
often resembles typical laterite so closely in its structures and mineral 
composition that when detached from its rock masses it could not be 
distinguished from pieces of ordinary ferruginous laterite (of non- 
detrital origin). It frequently contains ores of manganese — wad. 
