80 president's address — SECTION c. 



beds of the Lower Devonian series. Towards the later part 

 of the Lower Devonian, when the portion of the earth's 

 crust in Eastern Victoria was probably stationary, great 

 eruptions took place, forming lofty subaerial volcanic cones. 

 With the subsidence, which succeeded in early Middle 

 Devonian time, volcanic activity became locally extinct. 

 The Middle Devonian beds were then folded, and the 

 tipper Devonian were deposited unconformably upon them. 

 Probably before the subsidence, which took place in Upper 

 Devonian time, was completed, basaltic eruptions supervened. 

 The volcanic evidences in the Devonian beds of Victoria 

 therefore favour the inference that volcanic action ceased 

 locally in those areas of the earth's crust which were sub- 

 siding, but returned as soon as they became nearly stationary 

 or commenced to be re-elevated. 



The evidence in Victoria is probably as yet insufficient to 

 justify the conclusion that there was a direct relation in 

 Devonian time between volcanic activity and sedimentation 

 in that country. 



In the case, however, of the Permo-Carboniferous volcanic 

 rocks of New South Wales, there is, in the author's opinion, 

 a distinct relation between sedimentation and the volcanic out- 

 bursts of that period, as it is chiefly in those areas where the 

 Permo-Carboniferous sediments acquired a thickness of several 

 thousand feet that volcanic energy manifested itself. These 

 eruptions were all situated at no great distance from the shore- 

 line of the Permo-Carboniferous ocean. 



The eruptions of basalt in the Tertiary and Post-Tertiary 

 eras in Victoria, and in the Tertiary era in New South 

 Wales, appear to have taken place chiefly in those areas 

 where the earth's crust was stationary or undergoing elevation, 

 but to have ceased during subsidence. 



The comparative thinness, however, of the Tertiary sedi- 

 ments in Victoria and New South Wales does not warrant 

 the opinion that the volcanic action during the Eocene, 

 Miocene, Pliocene, or Pleistocene ages in either of those 

 countries was directly due to or assisted by sedimentation. 



There appears to have been a tendency on the ]mrt of the 

 Victorian volcanoes to migrate southwards, as the coast-line 

 receded in the same direction. 



As regards the highly interesting series of volcanic rocks 

 in Tasmania we as yet know very little. What we do know 

 is due to the labours of Count Strzelecki, Chas. Gould, Rev. 

 J. E. Tenison-Woods, F.G.S., R. M. Johnston, T. Stephens, 



