183 



Victoria in late Tertiary times, and which is known as the 

 Newer Basalt Period. The newer basalts, with their associ- 

 ated scoria and cinder cones, tuffs, etc., cover thousands of 

 square miles of Central and South-western Victoria, and ex- 

 tend almost to the South Australian border. 



The close relation in composition between the materials of 

 the Victorian Newer Basalt Period and those of Mount Gam- 

 bier has already been established. The relationship in space 

 of the volcanic features of the two States is quite clear from 

 fig. 5, and strongly suggests that the South Australian foci 

 are outlying centres of the one great area of activity. 



Professor Skeats/ 12 ' in describing the Victorian Newer 

 Basalts, says: — ''They form the Melbourne and Keilor plains, 

 and occur . . . over thousands of square miles in the 

 the Western District, passing over into South Australia and 

 connecting with the recent volcanic rocks of the Mount Gam- 

 bier district." 



(b ) Physiographic Evidence. — One of the features stressed 

 by those who have dealt with the denudation of cinder cones 

 is the remarkable way in which, in some cases, these very 

 porous beds will absorb the rainfall, lessen the ' 'run-off, " 

 and so preserve for ages an appearance of youth. While giving 

 full consideration to this fact, the physiographic evidence 

 (denudation, etc.) at Mounts Gambier and Schank points to 

 a fairly recent geological period for their age. Familiarity 

 with the volcanic features of a considerable portion of the 

 Newer Basalt area in Victoria suggests also that the age of 

 the cinder cones of Mounts Gambier and Schank is about 

 equal to, or less than, that of similar Victorian features. 



On those portions of the exterior of the cones that may 

 be unquestionably accepted as unaffected by the great col- 

 lapses that have taken place, the small amount of denudation 

 is remarkable. Wherever opportunity for testing the matter 

 arose, the general surface slope was found to be that of the 

 dip of the stratified material. 



( c) Fossil Evidence. — In the paper previously referred 

 to. Professor Skeats discusses the age of the Victorian Newer 

 Basalts, on the evidence of fossil leaves and fruits, etc., 

 and believes that the volcanic activity extended throughout 

 a considerable period, "from the Pliocene to the Recent, 

 if not Historic periods. . . . The tuffs about Tower Hill 

 overlie the geologically- recent dune -limestones of that 

 district." 



(12) -The Volcanic Rocks of Victoria," E. W. Skeats. Pre- 

 sidential address. Section C. A.A.A.S. 1909. 



