Section C. 



GEOLOGY AND MINERALOGY. 



ADDRESS BY THE PRESIDENT, 



Professor ERNEST W. SKEATS, D.Sc.,A.R.C.Sc., 



E.G.S. 



THE A^OLCANIC HOCKS OF VICTORIA. 



Introduction. 



The Volcanic Rocks of Victoria cover an area probably exceeding 

 10,000 square miles. They form the level plains of the Western 

 District, they occur as mountain masses near Warburton, Healesville, 

 and Marysville in Central Victoria ; the rugged areas near the Snowy 

 River in Gippsland are largely composed of ancient volcanic rocks, 

 while flows of Newer Basalt have been met with hundreds of feet 

 below the surface in several of the deep lead mines. Not only have 

 they a wide geographical distribution but among them are representa- 

 tives of very varied geological age and distinct petrological types, 

 giving rise to diverse types of scenery where they are exposed at the 

 surface. The geological literature dealing with Victorian volcanic 

 rocks is now fairly extensive, and is scattered through a variety of 

 publications. A general account is included in Murray's work on the 

 " Geology and Physical Geography of Victoria " (5), but the last 

 edition was published 14, years ago, and the chemical and petro- 

 graphical aspects receive scant treatment. 



The early work of the Geological Survey laid firmly the 

 foundations of our knowledge of the boundaries and stratigraphical 

 relations of the volcanic rocks, and the work of Selwyn, Ulrich, 

 Murray, and others is recorded in the Survey Reports and the official 

 maps. Our knowledge of the chemical and microscopical characters of 

 Victorian volcanic rocks has been mainly due to the remarkable work 

 of the late Dr. Howitt. Commencing his investigations in the early 

 seventies he was the pioneer, in Australia of scientific petrography, yet 

 his work, both chemical and microscopical, was characterised by such 

 accuracy and thoroughness that the great bulk of it will probably 

 stand with scarcely any modification. 



In Victoria, in recent years, the investigators in this branch of 

 research have increased in numbers, and foremost in importance is 

 the work of my predecessor. Professor Gregory. 



During the last four years my own research has been largely 

 concei-ned with Victorian volcanic rocks. In this work, and in teaching 

 the subject, I have felt the need of a modern general account which 

 should summarise the present position of • our knowledge. The 

 present paper is an attempt to meet this requirement, and it is 

 hoped that it will prove useful not only to workers in Victoria, but 



