PRSIDENTIAL ADDRESS. 27 



The central and western parts of this great valley are 

 occupied by the basaltic lavas mapped on the sheets of the 

 Victorian Geological Survey and recently described in 

 detail by Professor E. W. Skeats. 1 This east to west sag 

 of the trough of the " great valley " has led to the isolation 

 of the Wannon Trias-Jura area from that of the Otway 

 area, as the result of the inflow of the sea and deposition of 

 marine sediments over this part of the basin in Tertiary 

 time. The isolation has been further completed still later 

 by the outflow of vast sheets of basaltic lava. Dr. T. S. 

 Hall 2 has emphasised the isolation of the Otway region as 

 the result of this subsidence along the great valley in his 

 chapter " The Otways as an island." Mr. Reginald A. P. 

 Murray 3 has given a brief account of the metamorphic 

 rocks and crystalline schists of Victoria and their trend 

 lines, as well as of those of the older Palaeozoic rocks. He 

 remarks that (op. cit., p. 34) "The leading characteristics 

 of the Lower Palaeozoic rocks of Victoria are the normal 

 N. Westly to N. N. Easterly strike, and the high rate of 

 inclination of their bands caused by the crumpling or fold- 

 ing process to which they were subjected at a period not 

 long subsequent to their deposition etc." 



According to R. A. F. Murray, following A. R. O. Selwyn, 

 Victoria as regards its older rocks and the lines of folding 

 in older and newer Palaeozoic time is a vast syncline extend- 

 ing from the crystalline schists of the Wannon and Glenelg 

 Rivers on the west to the similar rocks of the Mitta-Mitta 

 massif, or Benambra Highland on the east (op. cifc., pp. 37, 

 — 78). Professor Skeats figures as Archaean 4 (op. cit., p. 

 231) the foundation rocks between the Hummocks and the 



1 Kep. Aust. Assoc. Adv. of Sci., Brisbane, 1909, pp. 173 - 229, pis. i - iv. 



2 Victorian Hill and Dale, by T. S. Hall, m.a., d.sc, Melbourne, T. C. 

 Lothian, 1909, pp. 99-106. 



s Victoria, Geology and Physical Geography. By authority, Melbourne 

 1887, pp. 36, 37. 



4 Rep. Auatr. Assoc. Adv. of Sci. Brisbane, 1909. pi. i, p. 230. 



