68 



111 the small water-rolled pebbley enclosed in the " Bay of 

 Biscay" soil, which I have elsewhere endeavoured to prove to 

 have originated in primeval mudflats and shore marshes. 



In Europe, and indeed through the whole extent of the old 

 world, one glacial period (or several such in succession) has 

 been ])roved to have been prevalent subsequent to the Tertiary 

 era, during which the diluvial unstratified clays, &c., were 

 deposited. If, therefore, while the whole of the Peninsula was 

 submerged, analogous conditions are assumed, several pheno- 

 mena, peculiar to this section of time, admit an easy explana- 

 tion. 1. The very obscure stratification of the lower and 

 major part of the mottled " Ardrossan clays" forming the 

 present abrupt sea cliffs, and much resembling in structure 

 those forming the banks of the Torrens near the Exhibition 

 Buildings, which competent authorities compare with the 

 boulder clay of England, and the loess of Germany in aspect 

 and structure. 2. The rounded knobs and polished surfaces 

 of the Ardrossan sandstone, where protruding from the soil, 

 which are as smooth as glass frequently, and of such hardness 

 and solidity that a steel hammer produces hardly any impression 

 upon them, and rebounds as from an anvil. 3. The reason would 

 appear why the various ingredients of them appear so sharp- 

 angled and so little rolled, this being a natural consequence of 

 carriage by ice. However, these are as yet conjectures, await- 

 ing to be proved or rejected by future investigations, when the 

 surface will be more exposed by the destruction of the obstruc- 

 tive, dense scrubby vegetation, and pierced by cuttings and 

 wells. As far as ascertained facts go, so much seems sure that 

 the whole Peninsula has been under water subsequent to the 

 Tertiary j^eriod, though very likely only to an inconsiderable 

 dejDth in respect of its highest points, the accumulated thick- 

 ness of the respective deposits (exceeding 90 feet) being 

 referable to very gradual subsidence, long continued. 



In respect of the wide spread of ferruginous conglomerate 

 or Upland Miocene (Prof. Tate), but here very rare, my 

 impression is that it is intermediate in age between the 

 Turritclla grits and the Ardrossan clays, and I entirely 

 concur with the ojiinion of Prof. Tate, who assigns it to the 

 Upper Miocene. Only one small patch of it has been seen by 

 me in this locality identical in appearance with the same as 

 occurring north of Gawler, viz., at Yorke Valley, where it is 

 associated with analogous soil and vegetation as at the former 

 locality. A similar small layer, with TurrifeUa Ahlliigcp casts, 

 in the upper part of the cliffs at Muloowurtie is clearly assign- 

 able to a preceding period. 



AVhcn our present hills and higher grounds again and finally 

 emerged from the sea, the low lands between them (which I 



