6 



PLANT HABITS AND HABITATS IN THE 



sheets of salt-incrusted clay, or damp mud and salt marsh. . . . Owing 

 to the absence of recent fold mountains the rehef of the continent depends on 

 the weathering of the old plateau and the formation of highlands and low- 

 lands by the uplift or subsidence of wide tracts of country." 



The same writer divides the continent of Australia into the Eastern 

 Highlands, the Great Plains, and the Western Plateau. The rela- 

 tive extent and position of each division is indicated in figure 1. It 



Fig. 1. — Physical divisions of Australia, after Gregory, ]916, to which has been added the 10-inch 

 isohyet. The shaded areas have an altitude of 1,000 feet or more above the sea. 



will be seen that the desert-arid regions lie in the western and cen- 

 tral divisions and that possibly half of the area within the 10-inch 

 isohyet has an altitude of 1,000 feet or more. On the other hand, a not 

 inconsiderable proportion of the whole of the desert-arid regions is 

 situated in the artesian basin of the Great Plains regions and is below 

 the level of the sea. 



The Western Plateau is not level, but several mountain chains rise 

 upon it; certain of these attain to considerable altitude, as, for example, 

 Mount Woodrofe, of the Musgrave Range, which is over 5,000 feet 

 above the sea, approximately 3,000 feet higher than the surrounding 

 plain (Jack, 1915). 



