51 
Records of the Geological Surrey of India. 
[vol. vr. 
may have been at work on either side to aeeelerate or to retard. I only wish to point out 
that there is no presumption, either paleontological or mechanical, that these Narbada deposits 
arc older than the late Pleistocene. 
If we turn to -the great, Gangetic valley, the old alluvium of which Falconer ranked 
with the Narbada beds, the physical arguments lead us to a like conclusion. Here we have 
not to deal with a rock-basin ; and the conditions are more appreciable. In the upper part 
of its course the Ganges cuts a broad abrupt valley, 60 to 100 feet below the level of the 
adjoining plains. In the lower region of the plains the denudation has taken a wider 
sweep); the old alluvium has for the most part been removed, isolated remnants of it only 
being found; and those, at least towards the modern delta, are being enveloped in the 
encroaching deposit of its alluvium. On the whole, the features of denudation in the Ganges 
valley seem to imply that this action was brought about by the subsidence of a former 
delta of greater extent than the present one, not by an elevation of tlic mountain region. 
Along the upper edge of the plains, the minor mountain-streams are still massing deposits 
continuously over the old alluvium ; and in some of these recent torrential accumulations a 
fossil Hindu village has been dug out. If we now turn to our comparisons, it is evident 
that the signs of change and of work done here are nothing like so great as that recorded 
of the Rhine and the Danube iu their valleys within post glacial times. Or absolutely, 
even stretching to the utmost the legitimate assumption of comparative stability, of condi¬ 
tions in India, ws can hardly reduce our estimate of the necessary duty of such a river as 
the Ganges, during the period allowed by a minimum computation for the lapse of time 
since the glacial period of Europe, to the amount of work I have indicated. So that here 
again the opinion obtrudes itself, that these old ossiferous alluvial deposits are not more 
ancient than the late Pleistocene. 
From the description given of the implement-bearing lateritic gravels of Southern India 
by my colleague Mr. R. Brace Foote (Quar. Jour., Geol. Soc., London, Vol. XXIV, p, 484, 
1868, and Mem. Geol. Surv., India, Vol. X, 1872), I should think they may be as old as the 
Narbada gravels. 
II. B. MEDLICOTT. 
July, 1873. 
Tie shells of the ossiferous deposits .—The shells Mr. Ilacket has placed in my bands 
for determination are all of them species, known to occur in the ossiferous gravels of the 
Narbada, a list of which is contained iu the Memoirs of the Geological Survey of India, 
Vol. 11, page 281. They are all of them in the mineral condition observable in the shells 
from these ossiferous beds, and some of them are embedded in the ordinary matrix of many 
of the fossils of the group, a gravel strongly cemented by lime. 
The most numerous and characteristic shells are Uniones, of precisely the same species 
and varieties as those now living on the spot, and it may be incidentally added, that no 
molluscous species is known to be included in these ossiferous beds which is not now living 
in the valley, though many species now living, have not as yet been detected in the gravels, 
which is a fact not without interest when the revolution is considered which has been 
wrought among the vertebrata since the days of the Hexaprotodon and Tetraprotodon, 
which, with numerous other pachyderms, proboscidians, and ruminants, then roamed over 
Central India, and disputed with man for mastery in the primeval world. 
Associated with the Uniones, occur also Bulimus pullus, Gray; Melania tuberculata. 
Mull.; Planorbis convexiusculus, B.; Lymnaaa acuminata, Lam. (?); and a Corbieula, pro¬ 
bably Corbicula Cor, Sow. 
