100 



IX. — Remarks. 



The distribution of tertiary basalts in South Australia 

 is confined to the South-Eastern portion of the State and 

 the Menzies district of Kangaroo Island. The principal 

 localities in the South-East are Mounts Gambler, Schank, 

 Burr, Mclntyre, Leake, and Muirhead ; beyond this there 

 is no other report of the occurrence of tertiary volcanoes or 

 outflows. There is a probability that the basaltic outflows of 

 Western Victoria are connected with the Mount Gambler oc- 

 currence, but at present no definite analytical or petro- 

 graphical work has been done in that direction, except what 

 has already been mentioned in this paper. 



X.- Conclusion. 



I am indebted to Professor Rennie for permission to use 

 the chemical laboratory, and to Dr. Cooke for information 

 and advice in connection with the analyses. 



My thanks are especially due to Mr. D. Mawson, B.Sc, 

 B.E., for his loyal support, and to Mr. Benson, B.Sc. and 

 Mr. Howchin, F.G.S., for their kind assistance and help in 

 the preparation of this paper. 



I also extend my thanks to Mr. P. G. Wykeham Bayly, 

 A.S.A.S.M., and Mr. F. Chapman, F.L.S., A.R.M.S., for 

 information concerning the Victorian basalts, and to Messrs. 

 Senior and Foorde, residents of Mount Gambler, for their 

 many kindnesses and advice as to routes. 



EXPLANATION OF PLATE II., 



Fig. 1. Vesicular olivine basalt, showing a dosette of 

 augite and phenocrysts of olivine containing magnetite inclusions, 

 in a microlitic groundmass of plagioclase, augite, and olivine, with 

 dark-brown glass and magnetite. (x20) 



Fig. 2. Vesicular olivine basalt containing a phenocryst of 

 olivine showing spheroidal cracking. (x20) 



Fig. 3. Vesicular basalt rich in felspar microlites contain- 

 ing many inclusions of magnetite. (x20) 



Fig. 4a. Vesicular vitrophyric olivine basalt. The flow 

 structure is indicated by the parallel arrangement of the micro- 

 lites. (x24) 



Fig. Ab. Vesicular olivine basalt (slaggy type) containing 

 a great many vesicules of varying dimensions. (x24) 



Fig. 5. Lherzolite showing predominant olivine, enstatite, 

 diallage, and a dark grain of picotite. ( x 16) 



Fig. 6. Lherzolite showing partial absorption of the olivine 

 and diallage in the black glass. The glass also contains a feAV 

 small grains of olivine. (xl6) 



