Three Expeditions into the Interior of Eastern Australia Volume II Part 49

(VIII.b.) Figure 6 Plate 48. Right series of molar teeth in situ.

(VIII.c.) Right ramus of the lower jaw.

Observation. These remains come nearer to the existing species than do those of any of the preceding genera; but after a minute comparison I find that there is a slight difference in the form of the grinders which, in the fossil, have the antero-posterior diameter greater in proportion than the transverse; the first grinder also is relatively larger, and of a more prismatic form; the upper incisors are less compressed and more prismatic; this difference is so well marked that, once appreciated, anyone might recognise the fossil by an incisor alone. There is a similar difference in the shape of the lower incisor. The fossil is also a little larger than the largest wombat's cranium in the Hunterian Collection.

From these differences I feel no hesitation in considering the species to which these fossils belong as distinct; and propose to call it Phascolomys mitch.e.l.lii.

NEW GENUS DIPROTODON.

I apply this name to the genus of Mammalia represented by the anterior extremity of the right ramus, lower jaw, with a single large proc.u.mbent incisor.

(IX.) Figure 1 Plate 49. This is the specimen conjectured to have belonged to the Dugong, but the incisor resembles the corresponding tooth of the wombat in its enamelled structure and position. See Figure 2 Plate 49 and a section of the wombat's teeth in Figure 7 Plate 48. But it differs in the quadrilateral figure of its transverse section, in which it corresponds with the inferior incisors of the hippopotamus.

To this, or to some distinct species, of equal size, have belonged the fragments of bones of extremities marked X., X.a., X.b.

GENUS DASYURUS.

Dasyurus laniarius, O. A new species. I apply this name to the species to which the following remains belong.

(XI.) Figures 3 and 4 Plate 49. Portions of the left side of the upper jaw.

(XI.a.) Figure 5 Plate 49. Portions of the left side of the upper jaw.

(XI.b.) Figure 6. Left ramus lower jaw, with last grinders.

(XI.c.) Figure 7. Anterior part of the right ramus of lower jaw.

This species closely resembles Dasyurus ursinus, but differs in being one-third larger, and in having the canines, or laniaries, of proportionately larger size.

The position of the teeth in the specimen marked XI.c. Figure 7, which are wider apart; leads me to doubt whether it is the lower jaw of Dasyurus laniarius, or of some extinct marsupial carnivore of an allied but distinct species.

GENERAL RESULTS OF PROFESSOR OWEN'S RESEARCHES.

The general results of the above examination are:

1. That the fossils are not referable to any known extra-Australian genus of mammals.

2. That the fossils are not referable, from the present evidence, to any existing species of Australian mammal.

3. That the greater number certainly belong to species either extinct or not yet discovered living in Australia.

4. That the extinct species of Macropus, Dasyurus, Phascolomys, especially Macropus atlas and Macropus t.i.tan are larger than the largest known existing species.

5. That the remains of the saltatory animals, as the Macropi, Halmaturi, and Hypsiprymni, are all of young individuals; while those of the burrowing Wombat, the climbing Phalanger, and the ambulatory Dasyure, are of adults.

I remain, dear Sir, etc.

(Signed) Richard Owen.

AGE OF THE BRECCIA CONSIDERED.

Nothing could be discovered in the present state of these caverns at all likely to throw any light on the history or age of the breccia, but the phenomena they present seem to indicate more than one change in the physical outline of the adjacent regions, and probably of more distant portions of Australia; at a period antecedent to the existing state of the country.

STATE OF THE CAVERNS.

Dry earth occurred in the floor of both the caverns at Wellington Valley and in the small chamber (Plate 28) of the breccia cave it was found, as before stated, beneath the three lines of stalagmite and the osseous breccia. It seems probable therefore that this earth once filled the cave also to the same line, and that the stalagmite then extended over the floor of red earth. Moreover I am of opinion that the interval between the stalagmite and the roof was partly occupied by the bone breccia of which portions remain attached to the roof and sides above the line of stalagmite. It is difficult to conceive how the ma.s.s of red earth and stalagmitic floors could be displaced, except by a subsidence in the original floor of the cave. But the present floor contains no vestiges of breccia fallen from the roof, nor any remains of the stalagmitic crust once adhering to the sides, which are both therefore probably deposited below the present floor.

In the external or upper part of the same cave, as shown in Plate 45, the floor consisted of the red dust, and was covered with loose fragments of rock, apparently fallen from conglomerated ma.s.ses of limestone and breccia which also however extended under the red earth there. Thus it would appear that traces remain in these caverns: First, 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 a.s.sociated 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 stalact.i.tes 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 s.p.a.cious 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 acc.u.mulation 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 to the existence, in at least the same districts, of the present species.

STATE OF THE BONES.

No entire skeleton has been discovered, and very rarely were any two bones of the same animal found together. On the contrary even the corresponding fragments of a bone were frequently detected some yards apart (as for instance those in Figures 2 and 1 Plate 49).

PUTREFACTION HAD ONLY COMMENCED WHEN FIRST DEPOSITED.

On the other hand it would appear from the position of the teeth in one skull (Figure 4 Plate 48) that they were only falling out from putrefaction at the time the skull was finally deposited in the breccia, and from the nearly natural position of the smaller bones in the foot of a dasyurus (Figure 2 Plate 51) it can scarcely be doubted that this part of the skeleton was imbedded in the cement when the ligaments still bound the bones together. The united radius and ulna of a kangaroo (Figure 1 Plate 51) are additional evidence of the same kind; and yet if the bones have been so separated and dispersed and broken into minute fragments, as they now appear in this breccia, while they were still bound together by ligaments, it is difficult to imagine how that could take place under any natural process with which we are acquainted.

ACCOMPANYING MARKS OF DISRUPTION. EARTHY DEPOSITS.

It may however be observed that the breccia is never found below ground without unequivocal proofs in the rocks accompanying it of disruption and subsidence, and that the best specimens of single bones have been found wedged between huge rocks, where the breccia occurs like mortar between them, in situations eight or ten fathoms underground.

THESE PHENOMENA COMPARED WITH OTHER EVIDENCE OF INUNDATION.

That changes have taken place in the relative level of land and sea is evident from the channel of the Glenelg which is worn in the rock to a depth of five fathoms below the sea level. The sea must have either risen, or the earth must have subsided, since that channel was worn by any current of water for it is now as still as a ca.n.a.l, the tide making a difference of only a few inches.

The features on the sh.o.r.es of Port Jackson extend underwater, preserving the same forms as they have above it; while the bays and coves now subject only to the ebb and flow of a tide present extensive ramifications, and can only be considered the submerged valleys of a surface originally scooped out by erosion at a period when the land stood higher above the sea.

SALT LAKES IN THE INTERIOR.

The hills on the margins of the Australian salt lakes are always on the north-east side, or opposite that of the prevailing south-west winds. The formation of these hills is probably due to the action of the wind, the growth and decomposition of small sh.e.l.ls, the carbonate of lime disengaged by evaporation, and the concretion of calcareous matter and friable tuff so common in these ridges.

In two of the most remarkable, Mitre Lake and Greenhill Lake, a portion of the basin of each, between the hilly curves and the water, was filled by a dark-coloured perfectly level deposit, apparently of vegetable mould. This being of a quality different from that of the hills, it would appear that any process by which these heights may have originated through the agency of the water adjacent and the wind could not continue after this different formation had acc.u.mulated between them. Accordingly where this dark-coloured deposit is most extensive the curved hill concentric with the outer margin seems less perfect; but whether worn by time or sweeping inundations I cannot pretend to say.

That some affinity exists between such acc.u.mulations and the salt water in the lakes is the more probable from the present state of those of c.o.c.kajemmy, which occur in the bed of a former current, and between the rocky sides of a kind of ravine. Even in such a situation a mound of very firm ground has been formed on the eastern bank of each, and was found very convenient for the pa.s.sage of the ravine by the carts of the party.

(See above.)

In those hills beside salt lakes on the plains a tendency to regular curvature was the chief feature: the relative situation with respect to the water and the wind was always the same; while in some cases, where gra.s.sy flats had once been lakes, crescent-shaped green mounds were still apparent on the north-eastern sides of each. If these remains of salt water are of less volume than they have been formerly, as may be presumed from these circ.u.mstances; and if the waters according to Professor Faraday's a.n.a.lysis "are solutions of common salt and, except in strength, very much resemble those of the ocean,"* we cannot have much difficulty in believing that the sea deposited the water in these situations at no very remote period.

As a dark-coloured soil is also found in the ridges about some of these lakes we must look deeper for the original cause of such depressions in those extensive plains; and may attribute them either to cavities or protuberances in the lower rocks, which may not have been sufficiently filled or covered by the superinc.u.mbent deposits: or they may be due to partial subsidences in a thin stratum of limestone.