BY H. I. JENSEN. 559 



Victoria. — Afc Mt. Macedon in Victoria occurs a series of 

 phonolites and alkaline trachytes described by Professor J. W. 

 Gregoty.* He remarks that it is possible that Mt. Macedon was 

 formed at the beginning of the great series of eruptions which 

 ended with the formation of the basalt plains of Victoria. He 

 considers it to be the remnant of a great volcano which emitted 

 lavas and tuffs of intermediate to acid character. The sequence 

 was apparently first dacites, then trachytes and solvsbergites, 

 then trachy-phonolites and andesites, and lastly basalts. If we 

 leave out of consideration the dacites, concerning the supposed 

 age of which and connection with the alkaline lavas, the work of 

 Professor Skeats has lately cast serious doubts (proving them 

 Palaeozoic), the age and sequence as well as petrological character 

 of the rocks are identical with those of the Warrumbungles and 

 Nandewars in New South Wales. 



The Macedon group is situated on the south-western extremity 

 of the highly metamorphic Ordovician complex of Victoria. No 

 Mesozoic sediments occur in the vicinity. To the south lies a 

 subsidence-area, the Pliocene Melbourne basin. 



At Macedon the following lavas are represented — geburite 

 dacite, trachy-phonolite, solvsbergite, andesite, and basalt. The 

 andesite appears to occupy an intermediate position between the 

 basalt and the trachyte, but sufficient analyses have not been 

 made to permit of any deductions as to magmatic differen- 

 tiation. The analyses published by Gregory are very poor, and 

 seem quite unworthy of reliance. 



New South Wales. 



The Cambewarra Trachyte and Alkaline 

 Basalts of the Bumbo Flow and Minamurra 

 Flo w.f — These rocks belong mainly to the Permo-Carboniferous 

 period. The succession which has been ascertained was as 

 follows : — 



* Proc. Roy. Soc. of Victoria, 

 f " Geology of the Kiama-Jamberoo District," by Jaquet, Card, Harper, 

 Mingaye, and White. Records Geol. Survey of N.S. Wales, Vol.viii. Part 1. 



