ARID PORTIONS OF SOUTH AUSTRALIA. 43 



The main influences which shape the temperature of South Australia 

 are the latitude, the relation of the state to the balance of the continent 

 and to the Southern Ocean, and the topographical variation of the 

 state itself. 



The temperature conditions of the Lake Eyre Basin, of the Flinders 

 Ranges, and of the southern end of the central rift valley will be char- 

 acterized in connection with descriptions of the flora of these respective 

 regions. In this place it will be necessary only to refer to the tempera- 

 ture of the plateau region of the western portion of the state. 



As described in the preceding section, the Western Plateau is a vast 

 region, since it is united to the plateau of Western Australia. The 

 extreme north-south extent is approximately 700 miles. Not much 

 is known exactly in regard to the meteorological conditions of most of 

 the plateau. The reason for this lies in its sparse settlement and in 

 the fact that much of it is hardly more than explored. From the 

 usually meager notes of the rare explorer, however, it is known that in 

 the northern and western portions of the plateau there is a very con- 

 siderable daily as well as large seasonal variation in temperature. 



Howchin and Gregory (1909:145) state that in the inland and central 

 regions the diurnal variation may be as great as 40° to 50° F., and that 

 in winter, while the days may be very warm, the cold at night may be 

 sufficiently intense to freeze the contents of a water-bag into a solid 

 mass of ice. The same authors cite the observations made on tem- 

 perature by the Elder Scientific Exploring Expedition, 1891-92, which 

 crossed the plateau between the Peake and Western Australia borders. 

 In winter during the day the temperature was about 60° to 80° F., but 

 at night it dropped to 8° or 10° below freezing. White (1915:713), 

 speaking of the northern portion of the plateau, says that just before 

 reaching the foothills of the Musgraves camp was made in a dense 

 thicket — ''the night was bitterly cold and everything was frozen hard." 



Further south the temperature, especially of summer, is greatly 

 influenced by the Great Bight to the south. In an earlier account of 

 the general temperature conditions of the continent reference has 

 already been made to the drying effects of the desert winds, and it was 

 stated that these effects are to be experienced several hundred miles 

 from the deserts themselves. In the southern portion of the Great 

 Plateau region, however, opposite conditions may also be encountered. 

 For example, at Tarcoola, which is 100 miles or more from the Bight, 

 its influence is frequently met. The summer temperatures at the place 

 may be as high as 118° F., as unofficially reported, but after a wind 

 from the south sets in the drop in temperature is immediate and 

 considerable. It may be remarked that similarly situated regions 

 of the state also share the cooling effects of the winds from off the 

 southern sea. 



