44 



PLANT HABITS AND HABITATS IN THE 



Rainfall. 



South Australia is the only state of the Commonwealth in which the 

 area receiving 10 inches, or less, of rain is greater than the area which 

 receives more than 10 inches. The ratio of the two is roughly 6:1. 

 The 10-inch isohyet runs in a general east-west direction. The 15-inch 

 isohyet lying to the south has a fairly similar course, but the northern- 

 most point attained is at the southern end of the Flinders Mountains, 

 near Mount Remarkable. Between these two isohyets lies ''Goyder's 

 Une of rainfall," which marks the northern limit for the successful 

 growing of wheat. The pastoral occupations are mainly carried on in 

 the country of intermediate rainfall to the north of "Goyder's line," 

 although sheep in large numbers are raised in the far north. The 

 leading industries of the state can thus be said to be strictly limited and 

 made possible by the amount and the distribution of the rain. 



Table 10. — Rainfall of 1 inch or more occurring in S4 hours at Oodnadatta, Copley, and 

 Quorn, 1901-1906. 



The rainfall of South AustraUa is periodic. The seasons of rainfall 

 are the best marked in the southern portion. As one progresses north- 

 ward the distribution through the year is more equable until the far 

 north is reached, when the rainfall conditions typical of the central 

 portion of the continent are met. Thus at Adelaide, which may be 

 used to illustrate the rainfall conditions of the southern districts, about 

 80 per cent of the rain occurs during the cool season. The average 

 rainfall at Adelaide is 21.06 inches. At Quorn, near the southern end 

 of the Flinders Ranges and nearly midway in the Central Highlands 

 section of the state, the average yearly rainfall is 13.82 inches. Of 

 this, about 57 per cent occurs in the cool season. At Copley, near the 

 northern end of the Flinders and on the western side of the mountains, 

 the amount of rainfall in the cool season, April to August, is about 38 



