president's address — SECTION c. 65 



In the mountain known as the Cobboras, in Eastern 

 Victoria, it attains an elevation of 6000 feet above the level 

 of the sea, sloping down to an altitude of about 1000 feet, 

 where it disappears under the marine Tertiaries near the 

 coast. The series rests uncomformably on Silurian sediments, 

 the latter having a thickness of perhaps 30,000 feet, and is 

 capped in places by limestones of Middle Devonian age. 



Mr, Howitt considers that these rocks were erupted from 

 a series of volcanoes on a meridional line of fissure, the 

 Cobboras forming the denuded stump of one of them. The 

 lavas and tuffs of this series are considered to be chiefly sub- 

 aerial, but partly subaqueous, 



Mr. Murray remarks with reference to these volcanoes,* 

 " This volcanic chain probably resembled, on a smaller scale, 

 that now in action in the Andes of South America, Its 

 position is worthy of notice, as it includes portion of the 

 present Cordillera, and extends southward from where the 

 latter now diverges suddenly to the west of Forest Hill 

 directly in the line of prolongation of the general course of 

 the Cordillera through New South Wales from Mount 

 Kosciusko to Forest Hill, and the general bearing of the 

 chain from Forest Hill to the mouth of the Snowy would, if 

 produced, run through Tasmania. Whether the crest of the 

 land surface, which once connected Australia with Tasmania, 

 was on this line or further to the westward is a matter of 

 speculation, but it does not appear unlikely that the igneous 

 belt extended to Tasmania, either as a wholly terrestrial or 

 partially marine chain of volcanoes. If the former, the con- 

 nection as a land surface was probably severed by denudation 

 early in Middle Devonian times. It would be interesting to 

 ascertain whether, in the older igneous rocks of Tasmania, 

 the same evidences are observable as those which justify 

 the conclusions arrived at by Mr, Howitt as to the origin of 

 the Snowy River belt of porphyries." 



By the severance of Tasmania fi'om Australia in the Middle 

 Devonian time, Mr. Murray presumably means the tem- 

 porary severance, as of course the fauna and flora of Tasmania 

 both indicate that the final severance of Tasmania from Aus- 

 tralia did not take place until late Tertiary or possibly even 

 Post-Tertiary times. The suggestion of Mr, Murray's that 

 this chain of Lower Devonian volcanoes may have been con- 

 tinuous into Tasmania is worthy of the consideration of 

 Tasmanian geologists. If Mr. R. M. Johnston's cautiously 



* Loc. cit, pp, 76-77. 



