ARID PORTIONS OF SOUTH AUSTRALIA. 35 



PHYSICAL ENVIRONMENT OF THE VEGETATION OF 

 SOUTH AUSTRALIA. 



PHYSICAL GEOGRAPHY. 



The state of South Australia comprises about 12.8 per cent of the 

 area of AustraUa. It lies between south latitude 28° and about 38°, 

 and longitude 129° and 141° east from Greenwich. The state, there- 

 fore, is wholly included within the temperate zone. In latitude 

 South Australia roughly corresponds with central Chili, Argentina, 

 and southern Africa, and in the northern hemisphere with Algeria, 

 southern Spain, and southern Italy, northern Egypt, Palestine, and 

 the most of Asia Minor, and northern China and Japan. So far as the 

 climate is concerned, as will be shown below, the state probably most 

 nearly resembles southern California, the Mediterranean region, and 

 southern Africa. 



South Australia may be fairly \7ell divided into three physiographic 

 general regions, as indicated in figure 10, page 34. These may be 

 referred to as the western plateau, the (central and northwestern) 

 highlands, and the lowlands (of the south and east). 



The western plateau is an eastern continuation of the great plateau 

 of Western Australia, which embraces about half of the land surface 

 of the continent. So far as concerns the portion of the plateau within 

 the borders of South Australia, it can be divided into three leading 

 physiographic formations, which may be referred to as the Bunda 

 plateau or Nullarbor plains, the Lake Torrens plateau, and the desert 

 sandstone tableland. 



The country which lies along the Great Australian Bight, and extend- 

 ing about 150 miles inland, constitutes the region known as the Nullar- 

 bor plains, from its supposed treeless character, or Bunda plateau, 

 from the native name for the cliffs. The plateau rises from about 250 

 feet at the sea to 800 or 1,000 feet along the northernmost portion. 

 It is a limestone plain of Miocene age and constitutes an extension of 

 the older plateau of Western Australia. 



The Lake Torrens plateau lies to the west of Lake Torrens, or, more 

 exactly, to the west of the great valley of South Australia. It is of 

 limited extent and is made up in part of flat-topped hills west of Point 

 Augusta, known as the Tent Hills. It attains its greatest width just 

 to the west of Lake Torrens (Howchin and Gregory, 1909 : 93) and is 

 much older, geologically, than the Nullarbor plains, being of the same 

 age as the Flinders Ranges (Howchin and Gregory, I. c). 



The third tableland, the Desert Sandstone, "once extended over 

 most of central and northern Australia. * * * it represents the 

 old land and fresh-water deposits which accumulated after the Cre- 

 taceous sea drained off from central Australia." The desert sand- 

 stone tableland extends from Copley north and forms the general fea- 



