lx. 



limestone that it is on their surfaces that the " Bay of Biscay" 

 land prevails. This name is applied to tracts covered with 

 mounds or ridges grouped in the most irregular way, and 

 without any relation to the natural slope of the surface. The 

 ridges, which rarely exceed a foot in height, are composed of 

 clay, whilst the depressions are occupied by alluvium or sandy 

 loam ; and though it is generally held that the soil of the de- 

 pressions extend in depth, yet my observations are totally 

 opposed to that view. How the depressions have been formed 

 on the clay soil, and how they have been subsequently partially 

 filled, are questions which I hope will occupy the attention of 

 some member of this Society. 



On the Murray plain these clays are surmounted by sands, 

 which occupy ridges surrounding plains constituted of the 

 former ; and though proof is wanting of their cotemporaneity 

 with the Upland Miocene, yet it is not unlikely that they 

 belong to the same epoch. 



Immediately to the west of Lake Torrens the country is 

 occupied by hard sandstones, clays, thin beds of ironstone, and 

 gypsum ; and, according to my informant, very extensive sec- 

 tions of these strata are exj>osed in the Bosworth Creek and at 

 Andemokka. At Bottle Hill, at one mile south from Edge Hill, 

 and between the Elizabeth Station and Coondambo, the hard 

 sandstones there have yielded to the researches of Mr. William 

 L. E. Gripps a plentiful supply of fossil leaves, for the most 

 part Eucalyptoid. ]N"o other fossils were observed in these 

 sections. ' 



Erom the published description of scientific travellers, and 

 from other sources of information, we gather that the rock 

 formation of much of Central Australia partakes of the 

 general character of the beds about the western shore of Lake 

 Torrens. It is, however, hidden over considerable tracts by 

 gravelly drift, in part derived from the subjacent sandstones. 

 And I think that there can be little doubt that it forms a part 

 of the "Desert Sandstone," so called by Mr. Daintree, because 

 of the sandy, barren character of its disintegrated soil. The 

 same author describes the formation in Queensland as uncon- 

 f ormably overlying Cretaceous rocks and underlying lava beds, 

 and states that all the available evidence tends to show that 

 this " Desert Sandstone " did at one time cover nearly, if not 

 quite, the whole of Australia. The position of the formation 

 is presumptive evidence of its Older Tertiary age, as so far as 

 is known the volcanic outbursts seem to belong to the Newer 

 Tertiary period. Mr. Daintree has found in it fossil wood, but 

 no marine fossils ; though he had recorded the occurrence of a 

 Tellina, but the locality he gives to it is a mistake. (See 

 Clarke, " Sedimentary Formations," p. 95). 



