356 
MANGANESE DEPOSITS OF INDIA : GEOLOGY. [PakT II : 
where the best ores seen iii situ form the highest portions of hills 4 and 
5 (see Plate 24). Now the deposits, the summits of which just 
reach the siirface of the ground, such as several of those on the Dumri- 
Khandala line of strike, are shown by the quarrying operations to be 
small hills or hillocks, separated one from another by considerable thick- 
nesses of allu\'ium, which covers up the lower ground between the 
hillocks. The character of the ore-bands on this lower ground has not 
been ascertained ; but, on the analogy of the manganiferous bands 
exposed at the surface, it is not probable that it consists continuously 
of manganese-ore, but rather that it consists, at least in part, of quite 
fresh or only partially altered manganese- silicate-rock. Hence it seems 
probable that, with these deposits also, if the covering of alluvium 
could be removed, we should find the bodies of manganese-ore forming 
the hiUs and hillocks, with manganese- siUcate-rocks on the necks between. 
So that we see that, judging from those deposits that form small hills 
projecting above the present plains, and probably from those now buried 
in alluviiun. it is necessary to suppose that the bodies of manganese- ore 
resist the agencies of denudation better than the majority of the mangan- 
ese-silicate-rocks ; the exceptions being the massive rhodonite-rocks, 
which seem to form just as marked hUls as the masses of manganese- 
ore, as, for example, in the highest portions of Manegaon Hill. Hence 
these bodies of manganese-ore must have been formed before 
the present topography was carved out by the weathering agencies. 
I have already mentioned the probability that a portion of the man- 
ganese-ores was formed by the direct compression of original manganese- 
oxide sediments duriag the Dharwar folding. Hence it might be 
these bodies of ore that gave rise to the hills when the rocks were carved 
out bv the weather ; whilst the ores formed by alteration of the man- 
ganese-silicate-rocks might haixe been formed subsequent to the pre- 
sent topography. That the g tc^er is probably not the case is shown 
by the Mansar deposit, where it is e\'ident that the ores have been formed 
by the alteration of manganese-silicate-rocks, even though they give 
rise to the highest portion of the hill- range in which the deposit is situ- 
ated. Hence we arrived at the conclusion that even the ores formed 
Man<ranese.ore de- alteration of the manganese-silicate-rocks 
posits formed before must have been formed largely, if not entirely, 
pre.sent topography. ^^^^^^ topography of the Country assumed 
its present shape. This deduction agrees with the dry condition of the 
hill deposits, mentioned on page 355. This does not tell us, however, 
whether the ores were all formed in Archaean times on the analogy of 
