Quart. Journ. Geol. Soc. vol. xxiii. p. 7, suggesting that they were " Rhaetic."
A thorough examination of these by Charles Moore, Esq., F.G.S., the results of which were detailed in Quart. Journ. Geol. Soc, vol. xxvi., led him to the conclusion that the Wollumbilla beds have their nearest representatives in the Oxford Clay. But it is possible that fossils from different localities, or perhaps drift specimens, have been mixed up, as he says " it is not easy to decide with certainty as to the exact position of the fossils that come from Wollumbilla. The Lias, the Great Oolite, the Oxford Clay, the Portland Oolite, and the Cretaceous beds may each put in a claim ; but that of the Oxford Clay appears to be the strongest."
The Bungeworgari and Amby river-beds are considered by Moore to be Cretaceous. This much then can be asserted, that all the great plains of Queensland westward of the main coast-range consist of subaerially decomposed Oolitic and Cretaceous shales, limestones, and sandstones, or the river-detritus of such, redeposited on their surface.
That this portion of the Mesozoic system extends throughout the whole of Central Queensland to Western Australia is also more than probable, hidden, however, over large areas by " Desert Sandstone."
The finding, by Stuart, of a Cytherea ? (first mentioned by Clarke) on the Gregory river, a few miles north of Finnis Springs, and the extent of marly plains similar in character to those on the Flinders, the well-known occurrence of Cretaceous fossils in the Moresby ranges, and of Oolitic in other parts of Western Australia, favour this idea. We may look forward to the clearing-up of this point when the collections of the South Australian Telegraph party are described.
The only variety in the lithological character of the Flinders- and Thompson -river Mesozoic rocks, is the change from shale to fine- grained sandstone in the alternating beds, the shale greatly predominating ; its line of bedding marked by thin bands and nodular layers of argillaceous limestone.
One other peculiarity in the strata forming the series is the presence at intervals of thin layers of limestone having the well-known cone-in-cone structure.
This has more the appearance of a chemical precipitate than a mechanical deposit, and contains no fossils. Its analysis gave : —
CoNE-iN-coNE Limestone.
Insoluble in hydrochloric acid 14.920
Ammonia-precipitate 4.860
Carbonate of lime 75.458
Undetermined constituents 4.762
100.000
How far the Flinders and Thompson series have extended over the dividing ranges is not yet thoroughly determined.
On Pelican Creek, a tributary of Bowen river, near an out-station
