70 GKOLOGV OF MT. FLINDKlib AM) FAS8IFEKN DISTRICTS, Q., 



tricts, 1889. In that Report Mr. Rands refers to a fine sanidine- 

 trachyte, " apparently interbedded with " the Ipswich Coal 

 Measures, near Walton Station. This is the only place in the 

 district where Mr. Rands met with trachytes. On my own 

 visit to the district I unfortunately did not see the locality, for 

 neither do the maps show, nor could anybody I asked at Beau- 

 desert tell me of, such a place as Walton Station. The occurrence 

 referred to by Mr. Rands is probably not a truly interbedded 

 sheet but a fine-grained sill. 



Although the main object of my investigation in the present 

 paper is Mt. Flinders and the immediate neighbourhood, yet on 

 the present trip I extended my researches to a review of the 

 interesting volcanic rocks of the Fassifern district, of which I 

 hope later to make a closer study. In all my field work I have 

 had the benefit of the advice of Mr. Wearne, B.A., Princi])al of 

 the Ipswich Technical College, who is an e.Kcellent geologist and 

 is intimately acquainted w4th the district. 



The most fertile part of the Fassifern District is known as 

 the Fassifern Scrub, which has a diameter of about eight miles. 

 This area was originally covered with a dense jungle of vine- 

 scrub, though now most of it is under cultivation; and the strange 

 thing about it is that the underlying rock is essentially trachyte. 

 The trachyte-masses intrude sandstone of a very calcareous nature, 

 and are associated with trachyte-tuffs and were followed by 

 eruptions of andesitic basalts. The basalts of the adjoining 

 districts are forest-covered, the chief timbers being Ironbark 

 (^E. melanophloia and E, crebra), and Blue Gum {E. tereticornis). 

 We have, therefore, at Fassifern the inverse of the usual order 

 of things. Generally the basalts have scrub and the trachytes 

 forest, but here the trachytes have scrub and the basalts forest. 



The dense vegetation of the trachytes of the Fassifern Scrub is 

 due to three main causes : — 



1. There is a mixture of soils derived from alkaline trachyte, 

 from calcareous sandstone of the Walloon Coal Measures, and 

 from the numerous dykes of basalt which intrude the trachytes. 



