xliii. 



materials ; and towards the seaward margin by immense 

 swamps. No rivers originate in this plain, though a few short 

 ones traverse its western margin in their passage from the 

 Adelaide chain to the River Murray. 



To the north and west from Lake Torrens there stretch 

 almost unlimitable plains, somewhat similar in their character 

 to portions of the S.E. Plain. The western section is probably 

 coterminous with the Bunda Plateau, around the head of the 

 Great Australian Bight. 



Jukes (1846), Burr (1846), and other early geological 

 observers recognised these leading surface features of the 

 province, and relegated the strata of the hill ranges to the 

 Palaeozoic and metamorphic series, and the fossiliferous beds 

 constituting the plains to the Tertiary epoch. 



Pke-Sillriajn*. 

 Burr, occupying himself with the geological structure of the 

 country between Mount Arden and the South coast, and east- 

 wards of the meridian of Mount Arden, has given us a sketch 

 of the sequence of the strata of these ranges. He notes their 

 southerly dip, and considers them, probably, to correspond 

 with the Cambrian and Skiddaw systems of Sedgwick, having 

 been led to this belief from the circumstance of there being no 

 fossils in them. In his generalised section of the arrangement 

 of these old rocks he has not attempted to giA*e thicknesses ; 

 and it appears to me that he has inverted the true order. In 

 an ascending series he represents it as follows : — 



1. Quartzose sandstone. 



2. Dark-coloured slate. 



3. Limestone beds, frequently very impure, and passing into 



4. Slate and slaty beds (metalliferous) . 



5. Mica slate, chlorite slate, and thence frequently into 

 sandstone (metalliferous) . 



6. Grneiss, which is metalliferous, resting on 



7. Unstratified granite, and other igneous rocks. 



The strata composing the principal range of South Australia 

 have a general dip to the south-east, and show a succession of 

 clay slate with quartzite bands, crystalline limestones, mica 

 slate and other decidedly metamorphic rocks, and granite. 

 It is remarkable that the apparently less metamorphosed 

 strata occupy the lowest position, whilst the uppermost 

 stratum is gneiss, unless we regard the granite, which follows 

 next, in the light of the extreme of alteration of which the 

 gneiss is an earlier phase. That the highly metamorphic rocks 

 do not form the axis of the Adelaide chain is beyond dispute. 

 And in various traverses across the strike of the strata of our 

 hills I have failed to detect faults or inversion, which would 

 account for their exceptional position, whilst, on the contrary, 



