ARID PORTIONS OF SOUTH AUSTRALIA. 37 



graphic areas. Of these, the more ancient, Archsean, make up the large 

 and relatively high upland area in the extreme northwest portion of the 

 state, where are the Musgrave Ranges and others. Remnants of for- 

 mer extensive mountain ranges, similar ancient rocks, occur south of 

 Oodnadatta, and as isolated hills and low ranges to the west of the 

 great valley of South Australia. Of these, the chief may be said to be 

 constituted by the Gawler Range, and among the isolated hills, those 

 at Tarcoola and Wynbring. In addition, portions of the Flinders 

 Mountains, including parts of Mount Lofty Ranges near Adelaide, 

 belong to the ancient pre-Cambrian mountain system. In the region 

 west of the great valley the elevations of such rocks are for the 

 most part inconsiderable. It is the waste of the ancient granitic 

 rocks, which, according to Howchin (1909:67), has supplied the sand 

 in the region to the north of the Great Bight. The elevation of the 

 ranges referred to as being in the northwestern portion of the state is 

 very considerable, reaching an altitude of 5,200 feet, which is the great- 

 est altitude in South Australia. 



But the greatest area of highlands hi South Australia is made up of a 

 hilly or mountainous central region which extends from the southern 

 ocean due north to Maree (Hergott Springs), approximately 500 miles. 

 This elevated region may perhaps be regarded as a peneplain which 

 has become much worn down and much dissected by streams. It con- 

 stitutes one geographical unit. In the northern portions the mountains 

 bear the stamp of an arid climate, but in the south the outlines are 

 rounded from the accumulation of soil and are well covered with vege- 

 tation. 



Following Howchin, we can for convenience separate the Central 

 Highlands into three groups. Of these, the southernmost is made up 

 very largely of the ranges which together constitute the Mount Lofty 

 system. These attain an extreme altitude of 2,334 feet (Mount Lofty) . 

 The middle section is made up of peneplains and rugged hills, the highest 

 of which (Mount Bryan) is 3,065 feet. The general direction of the 

 mountains of the Central Highlands is north-south. They are separated 

 from one another by the undulating plains, peneplains, which, in the 

 middle section, along the line of the railway at least, do not attain a 

 greater altitude than 2,000 feet above the sea (Howchin and Gregory, 

 I. c., 86). The middle section joins the southern end of the Flinders 

 Mountains. Extending as it does north to Maree (Hergott Springs) 

 and east to Lake Fromme, the Flinders Range constitutes by far the 

 largest portion of the Central Highlands. In the region of Port Au- 

 gusta-Quorn the mountains attain an altitude of 3,174 feet (Mount 

 Remarkable), with Mount Brown and Devil's Peak, near Quorn, 

 slightly less. Mount Arden, about 10 miles north of Quorn, is one of 

 the lower summits. 



On its way north the railway parallels the eastern shore of Lake Tor- 



