26 T. W. E. DAVID. 



mentioned trending about E. 10° N., probably marks a fault 

 along this line. The great scarp to the west of Oradle 

 Mountain, 5,069 feet high, the highest point in Tasmania, 

 probably marks a line of major faulting with a heavy throw 

 to the west. At the same time the existence of the great 

 resistent sills of quartz-dolerite thrust over the thick masses 

 of soft sediment of the Trias-Jura and Permo-Carboniferous 

 systems afford exceptionally favourable conditions in this 

 part of the island for the formation of steep scarps by sap- 

 ping, unassisted by faulting. A prolongation of this hypo- 

 thetical line of faulting to the west of Cradle Mountain 

 trends towards Hobson's Bay, in Victoria. Another 

 possible dislocation line in Tasmania is the gap through 

 which the railway line from Launceston to Hobart passes 

 between Ross and Oatlands. There can be little doubt 

 but that in Tasmania block-faulting has assisted sapping 

 in producing the steep scarps of the ' tiers,' that inland 

 plateau so much of which is over 4,000 feet above sea-level, 

 with peaks such as Mount Wellington 4,400 feet, Mount 

 Field (or Humboldt) 4,721 feet, Ironstone Mountain 4,736 

 feet, and Oradle Mountain 5,069 feet above sea-level. 



Victoria. — A glance at Plate 2 at once reveals the 

 important fact that there are at least two widely divergent 

 trend lines in Victoria. First there is the obvious trend 

 of the Main Divide of Victoria from E. to W. Then there 

 are the older lines having a nearly meridional trend, which 

 mark the position of the Grampians, Howitt- Wellington 

 mountains, Snowy River porphyries, and the deep valleys 

 of the Kiewa and Mitta-Mitta Rivers, the former sunk 

 some 4,000 feet below the summit of the Bogong Mountain. 

 The geological map of Victoria shows that trending 

 sympathetically with the Main Divide is the belt of Trias- 

 Jura sandstone of the Wannon, Otway, and Gippsland areas. 

 Between the last two regions lies the great valley of 

 Victoria. 1 



1 The Geography of Victoria, by Prof. J. W. Gregory, d.Sc, f.b.s., p. 77 



