president's address. — SECTION c. 149 



South Australia is second to none of the AustraUan States in the 

 interest whioh attaches to its geological and physiographioal features. 

 It forms, in conjunction with portions of Western Australia, the geo- 

 logical axis of the continent ; within its boundaries the older rocks 

 have their most typical development, while some of its physiographioal 

 outlines have a higher antiquity than can be seen in any other part of 

 Australia. This is certainly true of the Permo-carboniferous glacial 

 land-forms, which in the Inman Valley and Mount Compass districts 

 still retain, over hundreds of square miles, a topography that was 

 actually sculptured by sub-aerial agents in Palaeozoic times. It is a 

 notable example of what Professor W. W. Watts, in his Presidential 

 Address at the British Association Meeting of 1903, called " fossil 

 landscapes." Speaking of British topography, he said, " It is extremely 

 probable that many of the present landscapes, not only in the midlanct 

 but elsewhere, may be really fossil landscapes, of great antiquity and 

 due to causes quite different from those in operation there at the present 

 day." The South Australian example of geographical survival, just 

 referred to, in its great age, vast extent, and unmistakable character, 

 is, so far as I know, unique in survivals of this kind. 



Tempting as it may be to include within our survey the older 

 land-forms of South Australia, the limitations of time and space 

 require that we should restrict our remarks to a narrower compass. 

 We purpose to pass imder review the Cainozoic order of succession, and 

 trace the gradual development of those physiographioal features that 

 exist at the present time. 



A very cursory examination is sufficient to convince us that, in 

 the field of our inquiry, we have to do with two very distinct physio- 

 graphical provinces. The low and broad watershed, which exists on 

 the south side of the inland lakes, forms the southern rim of the great 

 central basin and marks the boundary of thesephysiographioalprovinces. 

 The geology of these respective regions, as a whole, is so much in 

 contrast that they might well be regarded as distinct geological, as 

 well as physiographioal provinces, for there is very little in common 

 in the geological features of the two areas. Notwithstanding this 

 they have evidently been correlated in earth movements which they 

 have shared in common. While the northern and central portions of 

 the continent were below base-level and were building up sediments 

 during cretaceous times, the southern portions were above sea-level 

 and undergoing waste. Then, at the close of the Mesozoic periods, the 

 northern areas became elevated into the zone of weathering, while the 

 southern portions of the continent passed through a series of epeiro- 

 genic movements by which depression of the land, with sedimentation^ 

 alternated with elevation and waste. 



With the exception of the Permo-Carboniferous glacial beds there 

 »re no deposits in southern South Australia intervening between the 



