112 



moineter suspended two feet within the blow-hole registered, 

 after the lapse of three minutes, 70 degs. 



The post-miocene rocks of the Bunda Plateau are compara- 

 tively so insignificant, and because they form part of a series 

 which elsewhere assume considerable proportions, I will include 

 them in my general account of that group of strata. 



The Newer Tertiaries around the Head of the Great 

 Australian Bight. 



Between the Head of the Bight and Fowler's Bay the surface 

 is occupied with loamy and grassed flats alternating with sandy 

 ridges covered with mallee. The grass flats are margined with 

 spurs and terraces thickly covered Avith travertine. AVells 

 have been sunk on the travertine, and the older tertiaries 

 passed through to depths up to 180 feet or more, water being 

 always met with in a grey silicious limestone, which may be 

 coterminous with the chalky rock of the Bunda cliffs. The 

 water is more or less brackish, but for the most part the 

 quantity and quality increases towards the coast. 



The sand, which crowns all the higher ground inland, is pro- 

 bably derived from the waste of the granitic and quartzitic 

 rocks to the north. Though the period of its formation is un- 

 certain, yet I venture to suggest that it is of fluviatile origin,, 

 and is coterminous with the plant-bearing sandstones of 

 Ardnamukka, on the west side of Lake Torrens. 



Excepting the Bunda cliffs, the whole coast line of the south- 

 western part of this colony is constituted of post-miocene 

 rocks. The prevailing subter-structure of the country between 

 Eucla and Fowler's Bay is that of the older tertiary limestone, 

 and between the latter place and Port Lincoln it is that of 

 metamorphic rock, chiefly mica- schist, through which protrude 

 granitic masses, overlain by derivative material, and flanked on 

 the seaboard by more or less consolidated calciferous sands. 

 The latter section of the country is represented on Brough 

 Smyth's geological map of Australia as occupied with tertiary 

 strata, but as I have shown (ante p. 103), the older tertiary of 

 this western country occupies a well-defined basin, and is not 

 coterminous with that of any other part of the province. 

 Most of the trigonometrical stations and the higher elevations 

 eastward from Fowler's Bay are granitic. 



Eastward from the Head of the Bight, the whole coast line 

 is flanked by sand dunes, generally based upon a false-bedded 

 consolidated sand ; which, however, occasionally attains a 

 moderate elevation above sea level. All the bluffs are com- 

 posed of the consolidated sand, and by its oblique lamination 

 and rapid decay of portions, there result those fantastic and 

 picturesque rock faces, needles, and scars which contribute SO' 



