50 PLANT HABITS AND HABITATS IN THE 



VEGETATION AND PLANT HABITATS IN VICINITY OF 



OODNADATTA. 



PHYSIOGRAPHY. 



The country to the south and to the west of Lake Eyre and Lake 

 Eyre South, as seen from the railway, has a monotonous topography, 

 although not without a certain diversity. As one goes west from 

 Maree (Hergott Springs) the land-surface on every side, except to the 

 south, is fairly level. Some distance on the south lies the north- 

 western spur of the Flinders Ranges, but in the other directions the 

 general flat expanse is broken only occasionally by low hills or mounds. 

 Maree lies on the southern edge of the great Australian artesian basin 

 and in its vicinity, as elsewhere along the line of the railway, mounds 

 mark the presence of springs. There are 50 or more of these springs 

 in the southern and southwestern part of the basin. The water is 

 charged heavily with mineral matter and upon evaporation leaves a 

 calcareous deposit. Thus the travertine mounds are formed. The 

 water flows out of the summit of the mounds and extends for a greater 

 or less distance from the base. The mound springs thus can carry 

 vegetation and are often the only green spots, truly oases, on a parched 

 and barren plain. 



But the leading characteristic of the country to the south of Lake 

 Eyre South is its flatness. On every side it is a plain, and to the north 

 it stretches as far as the eye can reach, a grayish-green plain that finally 

 merges in a mirage, suggesting flat expanses of a lake. Shortly before 

 reaching the station of Stuart's Creek the railway crosses what is 

 probably the southern edge of the bed of the lake of earlier times, 

 running below the level of the sea, and here, on the rare occasions 

 when filled with water, it may be seen from the railroad. Thus, in 

 July 1918, there seemed to be water in the south arm of the lake. 



After leaving Stuart's Creek the railway ascends gradually until 

 at Oodnadatta it is about 400 feet above sea-level. The topography 

 becomes more broken and presents several features of especial interest. 

 Beyond William Creek some worn-down pre-Cambrian hills extend, and 

 flat-topped hills may be seen to the west, which are probably outliers 

 of the desert sandstone tableland (Upper Cretaceous). Occasionally 

 sandhills were seen lying toward Lake Eyre. The railway line also runs 

 among low hills and along salt flats, and finally, not far south of Oodna- 

 datta, it crosses a wide and poorly defined river bottom, which at the 

 time of my visit was dry. Thus we have the leading topographical 

 elements of the Oodnadatta region, namely, the lower plain, itself 

 somewhat diversified, on which the railroad runs, the flat-topped hills, 

 the sand dunes, and the drainage channels. 



Oodnadatta, which is the present end of the railway running from 

 Adelaide, and approximately 700 miles from that city, is situated near 



