t, of an aqueous
deposit in the red earth found below the stalagmite in one cavern, and
beneath breccia in the other. Secondly, of a long dry period, as appears
in the thick crust of stalagmite covering the lowest deposit in the
largest cavern, and during which some cavities were filled with breccia,
even with the external surface. Thirdly, of a subsidence in the breccia
and associated rocks and, lastly, of a deposit of red earth similar to
the first.

TRACES OF INUNDATION.

The present floor in both caves bears all the evidence of a deposition
from water which probably filled the interior of the cavern to an unknown
height. It is clear that sediment deposited in this manner would, when
the waters were drawn off, be left in the state of fine mud, and would
become, on drying, a more or less friable earth.

STALAGMITIC CRUST.

Any water charged with carbonate of lime which might have been
subsequently introduced would have deposited the calcareous matter in
stalactites or stalagmites; but the general absence of these is accounted
for in the dryness of the caves. This sedimentary floor contained few or
no bones except such as had previously belonged to the breccia, as was
evident from the minuter cavities having been still filled with that
substance.

I do not pretend to account for the phenomena presented by the caverns,
yet it is evident, from the sediments of mud forming the extensive
margins of the Darling, that at one period the waters of that spacious
basin were of much greater volume than at present, and it is more than
probable that the caves of Wellington Valley were twice immersed under
temporary inundations. I may therefore be permitted to suggest, from the
evidence I am about to detail of changes of level on the coast, that the
plains of the interior were formerly arms of the sea; and that
inundations of greater height have twice penetrated into, or filled with
water, the subterraneous cavities, and probably on their recession from
higher parts of the land, parts of the surface have been altered and some
additional channels of fluviatile drainage hollowed out. The accumulation
of animal remains very much broken and filling up hollow parts of the
surface show at least that this surface has been modified since it was
first inhabited; and these operations appear to have taken place
subsequently to the extinction, in that part of Australia, of the species
whose remains are found in the breccia; and previously