44 The South Australian Naturalist. _ 



In the Perth and Adelaide areas the eastern blocks were 

 raised to form the Darling and Mount Lofty plateaus respec- 

 tively. Thus, also, the plateau of Jerusalem was formed, as 

 mentioned. Although the distances and heights in each of the 

 three cases are quite different. Figure 1 may be taken to repre- 

 sent the facts of each case. While these great movements of 

 earth architecture were going on, the rain fell, and the sun 

 shone, the winds blew, and the rivers ran. The wearing down 

 forces of sun and air and running water were persistently at 

 work, ajid while the sinking blocks were being removed from 

 their influences, the rising blocks were being more and more 

 vigorously attacked. The faces of the rising blocks were 

 seamed witli chainiels, which slowly worked their way back into 

 the highlands, and the great burden of rock waste carried out 

 of these valleys was carried down and spread over the sunken 

 blocks. Thus the beauty of the highlands was increased by the 

 formation of hill and valley, cliff and waterfall. The valleys of 

 the Torrens, the Swan, and their numerous sister streams were 

 formed, and all united in building up the wide plains of alluvial 

 material that now form the surfaces which were selected by 

 man for the sites of the cities of Perth and Adelaide. Mean- 

 while, the sea advanced and retreated, according to the varying 

 movements of the great earth blocks and the amount of allu- 

 vium brought down by the rivers. In all i)robability these 

 block movements were not sudden and catastrophic, but quite 

 gradual. They may be still going on, and an occasional tiny 

 "slip"' noAv and then I'attles the windoAvs and startles the 

 inhabitants of these areas. In the later movements, Perth was 

 favoured by a recent sinking of the ])lain, allowing the sea to 

 "drown'' portion of the valley of the Swan, and thus to provide 

 much of the charm and value of the site of Perth. 



Adelaide, however, is much nearer to the uplifted mountam 

 block, Avhich is higher, more dissected, and thus more varied and 

 picturesque than the Darling i)lateau face. So, owing to these 

 briefly described geological hapi)enings, Perth has its King's 

 Park," Swan Water, and the long line of blue hills in the back- 

 ground; while Adelaide has its fertile plains and park-like foot- 

 hills, its gorges and waterfalls, and— best-loved and most fre- 

 quented— "The Hills" of tlie .Mount Lofty Ranges.— (From 

 "The Australasian."). 



