1859.] WOODS TERTIARY ROCKS. 255 



west for 100 miles, terminating in a volcanic district on the River 

 Warm on, Victoria, about twenty miles over the boundary. With these 

 exceptions the country is an immense plain, with a gradual rise from 

 the sea. In the extreme south of the district are some extinct 

 volcanos. To the north of these there lies an immense chain of 

 swamps, the principal of which is called the Dismal Swamp — a 

 large series of marshes about thirty miles long by ten broad. To 

 the north of this again is a ridge of limestone (Tertiary), bordered on 

 each side by swamps or sandy flats, to Penola, where the Mosquito 

 Plains commence, and then continue right to the edge of the Mallee 

 Scrub. No change of the level occurs as far as the Mallee is known. 

 There can be no doubt that there is a continuation of the same flats, 

 and most probably of the same formations, as far as the River 

 Murray, a distance of 134 miles ; but, as the scrub is nearly impe- 

 netrable from the tangled nature of the brushwood, and quite so for 

 want of water, the geographical and geological features are not 

 known. The cliffs of the Murray to the north are of the same de- 

 scription of rock as that found lower down near Penola. The Mos- 

 quito Plains are a series of swamps, which are shallower than those 

 further north, and the water in them dries during the summer. This 

 makes them available for pasturage, but the land is very inferior. 



Before proceeding to describe the tertiary rocks, let me remark, in 

 reference to the country, that there are two kinds of soil met with. 

 The more common is a sand-peat, with stringy bark (Eucalyptus 

 Fabrorum) and a fern (Pteris escuhnta) as the only plants, besides 

 the usual scrub-growth of Australia. The sand is found on examina- 

 tion to consist of rounded particles of pink felspar and white or 

 transparent rounded grains of quartz, mixed with carbonate of lime 

 and black loam. The other kind of soil is generally of a chocolate 

 or black colour, with limestone-rock cropping out. It generally 

 supports good grass and trees of the Eucalyptus, Banlsia, and Casua- 

 rina class, besides many beautiful Acacias. Both these kinds of 

 country pass into another ; but, as a general rule, the sandy scrub is 

 found on very level ground, and the well-grassed soil on that which 

 Is undulating. I shall now proceed to describe the formation which 

 is universal in the district. 



Immediately under the surface-soil, which is always of small 

 depth, a white limestone is reached, of a compact texture, and con- 

 tinuing no fossils. In some places it is only a few feet thick; in 

 others, some twenty or thirty feel : and again in other localities it 

 is entirely absent. Whenever caves are found, such as I shall here- 

 after have occasion to describe, they are always immediately under 

 this non-fossiliferous bed: and where this is absent, I do not remember 



to have seen any caVOS. 



Immediately under the bed which I have described come the fos- 

 Biliferous limestone; Init there is do abrupt line of demarcation 

 between them, for the one passes insensibly into the other. This 

 rock is composed of fragments of Bryozoa, sometimes bo finely com- 

 minuted as only to show lure and there small fragments of organic 

 structure, imbedding occasionally the Terebrahda cotnpta, and Bre- 



VOI,. XVI. l'AUT I. U 



