Physical, Features of the Australian Alps. 103 



Detailed Topography of the Mitta Mitta Source 



Basin. 



The heads under which I propose to delineate this area 

 (enclosed with red Hnes on feature-map presented with this 

 paper) are — (1) Its topography ; (2) geological structure ; 

 (3) botan}^ or vegetation. To give even a fair outline in 

 each of these subjects would occupy more time than is 

 allowed for the reading of this paper, so that, for the present, 

 I shall confine my observations to its surface configuration, 

 or topography. The area under consideration embraces fully 

 1050 square miles of territory, made up of the following 

 drainage areas : — 



n c x1 nn , f Livingstone Creek, 138 square miles. 



1. southern affluents < ^ T . , °. t>. oi 



( Victoria Kiver 81 „ „ 



Cobungra River 98 „ „ 



Bmidarali River 65 „ „ 



Big River 160 „ „ 



Wombat Creek 61 



2. Western affluents 



t> 



Eastern affluents ^ Benambra Creek 233 



( Gribbo River 112 „ ,, 



Mitta Mitta, between Cobungra and Big Rivers 78 „ „ 



Omeo Lake drainage area ... ... 24 „ „ 



Owing to the western affluents draining* the Bogong High 

 Plains, and to the general altitude of the western watershed 

 line_, the volume of water brought down by these affluents 

 constitutes the principal source supply of the Mitta Mitta. 

 And, as an instance of the effect which the higher plateaux 

 have in regard to the collecting capacity of a source basin, 

 it is interesting to note that, although the Victoria River 

 only drains an area of a little more than half as much as the 

 Livingstone Creek, yet the former empties almost as great 

 (if not quite as great) a volume of water into its recipient, 

 the Cobungra, as the latter does into its recipient, the Mitta 

 Mitta; the Victoria rising at the Paw-Paw Plains, and 

 draining those tablelands, over 5000 feet above sea level, 

 while the highest point drained by the Livingstone Creek 

 hardly exceeds 4000 feet. 



Taking into consideration, first, the physical conformation 

 of the western watershed line which intersects the highest 

 plateau, the Bogong High Plains, we find it starting from 

 Mount Hotham, on the Dividing Range (at a much lower level 

 than that height), as a well-defined, narrow ridge, separating 



