PHYSIOGRAPHY OF THE AUSTRALIAN ALPS. 361 



plains table-land, 6,000 feet. This plateau, the highest in Victoria, 

 is further connected by a narrow, low, and sinuous ridge, with 

 Mount Bogong, the highest mountain in Victoria, at an elevation 

 of 6,508 feet above sea level. South from Mount Hotham, an 

 undulatory and sinuous ridge, separating the waters falling into the 

 Wongungarra and the Dargo Rivers (both tributaries of the 

 Mitchell), rises some eight miles distant from the Dargo High 

 Plains, 4,000 to 5,000 feet above sea level. 



An extension of the western watershed line of the Mitta Mitta 

 forms the picturesque Omeo Plains, a depressed table-land 2,000 

 to 3,000 feet, with a small lake, the Omeo lake, on its western 

 margin. 



Easterly from the Omeo Plains and on the watershed line 

 between the Tambo and Buchan Rivers (the latter a tributary of 

 the Snowy River), is situate the Nuninyong table-lands, 4,500 

 feet ; while still further easterly on the divide between the main 

 Snowy River and the Buchan, is found the Gelantipy table-land, 

 These elevated and now disconnected plateaux of basaltic rocks 

 would appear to have been united during Middle Tertiary times 

 as one vast mountain plateau. 



The physical features and scenery of the higher table-lands are 

 distinctively Alpine, and whether we examine the Kosciusko 

 plateau, or the Bogong High Plains, the surface features and 

 physiognomy of the vegetation are the same. 



PHYSICAL FEATURES OF THE MAIN VALLEYS. 



It follows from the remarks already made concei^ning the 

 former existence of a once vast extent of table-land throughout 

 the area now occupied by the Australian Alps, that the valleys 

 are mainly valleys of excavation. And that many of the higher 

 points within their catchment basins, are made up of those hai'der 

 rock masses which have longest resisted the detritive agencies by 

 which the softer rock masses were abraded. 



At the same time it is in the plutonic distuibances which 

 characterised the close of the Silurian, and extended througli the 

 Devonian periods, that we must recognize the influences which 

 dominated in the evolution of existing contours by the conversion 

 of the softer sedimentary rock masses into crystalline schists, or 

 the intrusion of molten masses, which on subsequent cooling 

 acquired a hard crystalline aspect. Similarly in Tertiary times 

 the iNIiocene lava flows, sealing up the valleys, have left dense 

 sheets of basalt which have resisted the denuding action of 

 the atmosphere while the softer adjoining ranges have been 

 degraded. The contours of the valleys there necessarily depend 

 on the character of the rock masses out of wliich they have been 

 excavated. 



Above the township of Harrietville, the upper affluents of the 

 Ovens are torrential, and have sculptured deep hollows in the flanks 



