100 Physical Features of the Australian Alps. 



notably Mount Bogong, 6508 feet at its northern ex- 

 tremity; Mount Cope, 6015 feet at its eastern rim; and 

 Mount Feathertop, 6303 feet at the south-west margin. 

 The Main Dividing Range, as at present existing, is not 

 an original axis of elevation, but, on the contrary, has 

 assumed its present position by a long-continued process 

 of denudation and erosion from a once extensive high- 

 land existing during miocene time, and of which such 

 peaks as Mount Wills and Mount Gibbo north of it, 

 and Black Mountain, Mounts Bindi, Baldhead, and Welling- 

 ton south of it, are some of the remaining representatives. 

 Some of the evidences of this ancient highland are found 

 in localities now occupied by coatings of basalt, overlying 

 miocene flora resting on Silurian rocks, some of the present 

 river valleys having eroded their courses along the margin of 

 these lava flows, leaving the height of the underlying strata 

 and the depth of the basaltic coating plainly discernible. 

 Such a case is noticeable at Mount Tabletop, along whose 

 margin the deeply eroded valley of the Dargo River passes, 

 leaving this isolated patch of basalt as a connecting link be- 

 tween the partially denuded coatings on the Bogong and 

 Dargo high plains. The numerous igneous dykes* traversing 

 the metam orphic schists along the valley of the Livingstone 

 Creek (admitting their contemporaneousness with the lava 

 flows existing on the higher elevations) seem also to me to 

 point to a period of higher elevation than at present exists, 

 the igneous dykes being the undenuded portions of an 

 ancient lava now covering the then existing miocene 

 plateaux. 



The present elevated plateaux, as might be expected, form 

 the gathering grounds of most of the principal streams. The 

 Omeo Plains tableland, however, is a noticeable exception 

 to this. Covering an area of 24 square miles, this depressed 

 tableland has a small lake in its centre, 3J miles long by 

 1J wide, which is fed by rains and the storm- waters from 

 the surrounding hills. It has no visible outlet, the character 

 of the country surrounding it consisting of open, treeless 

 plains, merging by gentle slopes into the encircling timbered 

 ranges. 



Owing to the proximity of the coast line, about 49 miles 



* There are two sets of igneous dykes within the area, the one intrusive 

 from deep-seated sources, the other as indicated — probable remnants of surface 

 lava flows. 



