174 president's address SECTION c. 



also to others interested in volcanic rocks who may not have access to 

 all the literature. During the preparation of this paper I have made 

 a bibliography of the most important papers dealing with the subject, 

 and this is added as an appendix. In the preparation of the biblio- 

 graphy I have to acknowledge considerable assistance from Messrs. 

 H. J. Grayson and H. S. Summers, M.Sc, of the Geological Depart- 

 ment of the University, wliile Mr. Grayson and Mr. H. C. Richards, 

 B.Sc, have also helped me in tlie preparation of the map and sections 

 which accompany this paper. 



It is hoped that this account of the Volcanic Rocks of Victoria 

 will not only serve to show in a general way what is at present known 

 concerning them, but, by revealing the considerable gaps in our 

 knowledge, will serve tc) direct attention to those rocks and areas in 

 which further research is required before our knowledge of them can 

 be regarded as even approximately complete. 



In order to emphasise their geological I'elations the volcanic 

 rocks will be described according to their a'ge, all those of a given 

 geological period being grouped together. 



The oldest rocks in Victoria are probably two areas of meta- 

 morphic rocks, consisting of schists and gneisses outcropping in the 

 one case near the Western boraei: of the State in county Dundas, and 

 in the other forming a belt of country in Gippsland, in N.E. Victoria. 



They have been regarded as altered Ordovician rocks, but, in 

 recent years, the opinion has been gaining ground that they are not 

 only Pre-Ordovician, but, probably, of Archtean age. Very little is 

 yet known of their petrological characters or original composition, and, 

 while it is possible that highly metamorphosed volcanic rocks are 

 represented among them, we have at present no evidence of their 

 existence. (AVe Plate I., Fig. 2, and Plate II., Fig. 1.) 



BASAL ORDOVICIAN. (?) 

 The " Hbathcotian " Series. 

 Geographical Distribution [See Map, Plate 4). 

 The oldest known volcanic rocks of Victoria consist of a series of 

 diabasic rocks associated frequently with cherts. The best known and 

 type locality is Heathcote, from which town a narrow belt of these 

 rocks stretches northwards for about 30 miles, forming the Colbinab- 

 bin Range, and ending near L. Cooper. Some miles south of Heath- 

 cote and east of Lancefield similar rocks occur, and the same associa- 

 tion is met with near Mount Stavely in W. Victoria (24), near Tatong 

 (33), and Dookie in N.E. Victoria (17 and 22), and, according to Mr. 

 Dunn (28), just N. of Nowa Nowa at the head of L. Tyers, in Gipps- 

 land. A serpentinous diabase with chert occurs at the Hummocks, a 

 few miles N. of Casterton in W. Victoria. The serpentine of Mount 

 Wellington, Gippsland, and the diabase occurring W. of Geelong may 

 belong to the same series, and the serpentine near the Limestone R. 

 in Benambra is regarded by Mr. Dunn as probably Heathcotian (30), 

 The cherty and slaty rocks of the phosphatic deposit near Mansfield, 

 of Edi, on the King R., and on the Divide, W. of the Macalister R., as 

 well as some rocks near Egerton, have been claimed by Mr. Dunn as 

 probably Heathcotian (7). 



