Imagens das páginas

Amongst the unstratified rocks are found quartzose, petrosilex, feldspathic, and claystone porphyries, granular quartz rock, columnar, shistose and amorphous greenstone, serpentine, basalt, trachyte, siliceous breccia, compact, massive, and foliated granular limestone.

Among the stratified masses are siliceous and argillaceous slates, grauwakes, grits, pudding-stones, and conglomerates.

We will select the most important localities illustrative of this epoch, and begin with the north-east of New South Wales.

1st. Port Stephens. — Throughout the tract of country which lies between Port Hunter, Port Stephens, and Mount Wingen, the sedimentary rocks of this epoch are found widely separated; each detached portion having its own strike or dip. In this dislocated structure some evidences are nevertheless discovered by which their former continuity may be traced.

Nearly midway between the river Karua and Raymond Terrace there is a very slight elevation or low ridge of siliceous breccia and greywacke, ranging east and west. On both sides of it the country is overspread with a coarse arenaceous deposit, no natural sections of which are found; but a quarry four miles from Raymond Terrace shows that it i3 composed of two distinct and conformable members, the upper a conglomerate, the lower a friable sandstone, used for building, and containing the following fossils : —

Fenestella internata.


Productus brachythcerus.
Terebratula cymbceformis.


Conxdaria levigata.

The sandstone and the conglomerate are but slightly inclined, and dip to the southward: at Raymond Ferry the conglomerate is found on the left side of the Hunter, almost at the level of its waters.

On passing due westward from Carrington to Booral, we find on a ridge ranging E. and W. a flaggy, greyish-blue argillaceous rock, in strata highly inclined, containing an admixture of calcareous matter and a good many organic remains, some of which, parallel to the laminar surfaces of the rock, are well preserved, and may be referred to

Littorina Jilosa,
Turritella tricincta,
Spirifer crebristria,

and the minute genus of Crustacea belonging to Cythere or Bairdia.

A further examination shows that this rock is associated with siliceous breccia and greywacke, which last has greenstone and feldspathic porphyry below. In the immediate vicinity are sandstones and conglomerates, similar to those of Raymond Terrace, at least in a mineralogical point of view; for the absence of natural sections precludes the discovery of the fossils.

At Booral, also, the three members of the group, namely, siliceous breccia, slaty blue argillaceous rock, and sandstone, appear. West of Strout, on the steep banks of the river Kama, four members may be easily traced; the lowermost greywacke, succeeded by a slaty rock, which in turn is succeeded by sandstone and conglomerates, as above described.

In tracing now the greenstone and feldspathic porphyry, which we saw lying below the flaggy argillaceous rock containing Icthyodondite, we see that

[ocr errors]

greenstone and porphyry, about the sources of the river Hunter, is associated with granite belonging to the first epoch; and hence that the above surveyed tract of the country, which for convenience sake we have named Port Stephens, would present the following section in the ascending order: —

Siliceous breccia.

Argillaceous flaggy rock with

-, , , . A, f Sandstone with Conularia.
*early horizontal | Conglomerate.

2d. At St. Patrick's Plains, Glendon, Harper's Hill, the stratified rocks of this epoch rest upon a siliceous amygdaloid, which abuts against greenstone and basaltic dykes. It is associated with a massive limestone, much broken, and containing—

Platyschisma oculus,


Spirifer Darwinii,


Pleurotomaria Strzeleckiana,
Fenestella internata, fossula.

3d. The Upper Hunter. — Here the rocks of the second epoch stretch from the environs of Dart Brook in a western direction, to Gummum Plains and Cassilis. About Coyal it seems to bifurcate to the west. In some parts of this zone, as in Dart Brook gulley, and in the gullies to the westward of Mac Arthur's Peak, the lowest bed is a fragmentary rock, composed of granite, feldspar, mica slate, and argillaceous slate: over this are a sedimentary clay-slate and greywacke, nearly vertical; next above is limestone of two varieties, compact, and foliated granular, in which the traces of organic remains are very indistinct. The whole is crowned by a great development of pudding-stones and conglomerates, in slightly inclined beds.

In some places the described strata are distinctly separated from those of the first epoch by erupted greenstone, as may be seen on the southern flank of Liverpool Range; sometimes they are found abutting against granite and greenstone, as is the case between Coyal and the sources of the River Goulburn.

4th. At the eastern environs of Cullen Bullen, the rocks of the second epoch are found stretching partly over the Honeysuckle range, partly over the Wolgan, and jutting out in a neck of land even as far as the western side of Mount King George: they embrace also Mount Victoria, and part of the Vale of Clywd. In this locality we see a fragmentary rock abutting against either greenstone and basalt, or sienite, over which lie clay slate and compact, blackish limestone, in a vertical position, which again are crowned by conglomerates nearly horizontal.

5th. To the eastward of Lake Barrabura, in the environs of Glenrock and Barber's Creek, gritstones and fine-grained slaty greywacke form the lowest bed of the group of rocks under consideration; between which and the granitic base we see quartzose porphyries and jasperoid rocks intervening. The compact limestone which comes next above is either in contact with gritstones, or with porphyries; and passes imperceptibly into fossiliferous limestone. At Amprier, and east of Glenrock, the fossils which this limestone presents are greatly obliterated, and for the most part, they are but slightly delineated on the weather-worn surface of the rock. They consist of

Amplexus arundinaceus.

Crinoidal stems, tyc.

6th. lllawara Of the rocks belonging to the

second epoch, this locality exhibits but the fossiliferous limestone, which we noticed in the described group of Harper's Hill: — that limestone is found amidst vast dislocations referable to different periods, and containing the following fossils —

Platyschisma rotundatum.


Pleurotomaria Strzeleckiana.


Terebratula hastata.
Belerophon micromphalus.
Spirifer Darwinii.


Theca lanceolata.
Conularia levigata.

Stenopora crinita.
Allorisvia curvatum.
Pachydomus antiquatus.





Orthonota costata.
Eurydesma cordata.
Pecten Illawarensis.
Productus brachythcerus.

7th. At Modbury West, the group of this epoch is seen resting against argillite and granite: its limestone likewise bears only a very indistinct fossiliferous impression.

8th. South-west of Arthursleigh, about Greenwich Park, the limestone is associated with greywacke, which is separated by greenstone and serpentine from the granitic basis. In all cases the superstructure is pudding-stone and conglomerates, all in nearly horizontal position; some much worn away; some still overtopping the surrounding country, as is the case six miles S. W. of Arthursleigh, and to the northward about Ballangola.

9th. To the westward of Lake Barabura and Lake George, the rocks of the second epoch extend almost

« AnteriorContinuar »