Three Expeditions into the Interior of Eastern Australia, Volume 2 / With Descriptions of the Recently Explored Region of Australia Felix, and of the Present Colony of New South Wales

by T. L. Mitchell

1. A light-coloured compact calcareous rock resembling mountain limestone; at Buree and Wellington, rising, at the former place, to the height of about 1500 feet above the sea.

2. A dark grey limestone appears at perhaps a still greater height on the Shoalhaven river; in immediate contact with granite.

3. A crystalline variegated marble is found in blocks a few miles westward of the above, near the Wollondilly.

4. Another variety of this rock is very abundant in the neighbourhood of Limestone plains on the interior side of the Coast ranges and near the principal sources of the Murrumbidgee. This contains corals belonging to the genus favosites; crinoideae are also found abundantly in the plains and distinguish this limestone from the others above-mentioned.

These rocks present little or no appearance of stratification.

A remarkably projecting ridge on the banks of Peel's river contained limestone of so peculiar an aspect as to resemble porphyry, and it was associated with a rock having a base of chocolate-coloured granular felspar. (See Volume 1.)

A yellow highly calcareous sandstone, apparently stratified, occurs near the banks of the Gwydir. Large rounded boulders of argillaceous limestone have been denuded in the bed of Glendon brook; and an impure limestone is found in the neighbourhood of William's river, both belonging to the basin of the Hunter and not much elevated above the sea. Calcareous tuff or grit may be observed in various localities, and calcareous concretions abound in the blue clay of almost all the extensive plains on both sides of the mountains.

A soft shelly limestone, most probably of recent origin though slightly resembling some of the oolites of England, occurs extensively on the southern coast between Cape Northumberland and Portland bay where it forms the only rock with the exception of amygdaloidal trap.

GRANITE.

Granite or granitic compounds are more or less apparent at or near the sources of the principal rivers; but with the exception of the Southern Alps and some patches in the counties of Bathurst and Murray this fundamental rock is visible in Australia only where it appears to have cracked a thick overlying stratum of ferruginous sandstone. Thus near the head of the river Cox where the latter attains its greatest elevation, and from the character of the valley has evidently been violently disturbed, we find granite in the valley near the bed of the stream.