PLATE 44: VERTICAL SECTION AND GROUND-PLOT OF TWO CAVERNS AT WELLINGTON VALLEY.
From Nature and on Stone by Major T.L. Mitchell.
Published by T. and W. Boone, London.
This lower cavern terminated in a nearly vertical fissure which not only ascended towards the external surface but descended to an unascertained depth beneath the floor. At about 30 feet below the lowest part of the cavern it was found to contain water, the surface of which I ascertained was nearly on a level with that of the river Bell. Having descended by a rope I found that the water was very transparent but unfit to drink, having a disagreeable, brackish flavour.
This lower cavern is much contracted by stalactites and stalagmites. After having broken through some hollow-sounding portions (at O and N) we entered two small lateral caverns and in one of these, after cutting through (at I) about eight inches of stalagmitic floor, we discovered the same reddish earth. We dug into this deposit also, but discovered no pebbles or organic fragments; but at the depth of two and a half feet met with another stalagmitic layer which was not penetrated. This fine red earth or dust seems to be a sediment that was deposited from water which stood in the caves about 40 feet below the exterior surface; for the earth is found exactly at that height both towards the entrance of the first cavern and in the lateral caverns. (See Plate 44.)
That this cave had been enlarged by a partial sinking of the floor is not improbable, as broken stalagmitic columns, and pillars like broken shafts, once probably in contact with the roof, are still apparent. (See the view of the largest cavern Plate 43.)
OF THAT CONTAINING OSSEOUS BRECCIA.
Eighty feet to the westward of this cave is the mouth of another of a different description. Here the surface consists of a breccia full of fragments of bones; and a similar compound, confusedly mixed with large blocks of limestone, forms the sides of the cavity. This cave presents in all its features a striking contrast to that already described. Its entrance is a sort of pit, having a wide orifice nearly vertical, and its recesses are accessible only by means of ladders and ropes. Instead of walls and a roof of solid limestone rock we found shattered masses apparently held together by breccia, also of a reddish colour and full of fragments of bones. (Plate 45.) The opening in the surface appears to have been formed by the subsidence of these rocks at the time when they were hurled down, mixed with breccia, into the position which they still retain. Bones were but slightly attached to the surface of this cement, as if it had never been in a very soft state, and this we have reason to infer also from its being the only substance supporting several large rocks and at the same time keeping them asunder. On the other hand we find portions of even very small bones, and also small fragments of the limestone, dispersed through this cementing substance or breccia.
FIRST DISCOVERY OF BONES.
The pit had been first entered only a short time before I examined it by Mr. Rankin, to whose assistance in these researches I am much indebted. He went down by means of a rope to one landing-place and then, fixing the rope to what seemed a projecting portion of rock, he let himself down to another stage where he discovered, on the fragment giving way, that the rope had been fastened to a very large bone, and thus these fossils were discovered. The large bone projected from the upper part of the breccia, the only substance which supported as well as separated several large blocks, as shown in the accompanying view of the cave (Plate 45) and it was covered with a rough tuffaceous encrustation resembling mortar. No other bone of so great dimensions has since been discovered within the breccia. (See Figures 12 and 13, Plate 51.)