122 E. 0. Teale: 



and th(e Bairnsdale-Orbost railway line intersects the southern end 

 of the mass, showing some good sections in one of the cuttings a 

 few miles east of Bruthen. The rock is of medium grain and pink 

 colour, closely resembling the better known Gabo Island granite, 

 with which it is most probably to be correlated genetically. At the 

 locality east of Bruthen, the granite intrudes sedimentary rocks, 

 presumably of Upper Ordovician age. 



There is, therefore, no opportunity to study the relationship to 

 the volcanic rocks of the Snowy River Series. 



Another occurrence lies to the east of the Tara Range in the vicin- 

 ity of the now deserted district of Bete Bolong. The granite here 

 takes the form of two elongate elliptical masses more or less parallel, 

 with their longer axes striking north easterly across the Snowy 

 River. The surrounding rocks are entirely sedimentary, again pre- 

 sumably Tapper Ordovician. This area was only very hurriedly 

 visited, at one place on the western margin. Two type^ were noted, 

 one a fine grained aplitic variety, and the other a distinctly horn- 

 blendic form without the prevailing pink colour of the types previ- 

 ously mentioned. Distinct contact alteration is shown in the sedi- 

 ments in the vicinity, characteristic hornfels being common. As 

 the area examined at Bete Bolong was very limited, it is impossible 

 to say wliether or not the position seen is typical of the whole of 

 the area. 



Thin sections of the granite from all tlie above localities were 

 erxammed. 



No. 98, Tara. Range, and that from near Bruthen, most nearly 

 resemble each other, but liornblende is most abundant in the Bete 

 Bolong example. 



.They all agree in having at least three types of felspar — ortho- 

 clase and two triclinic forms; much of the felspar is partly kaolin- 

 ised, and, therefore, unsuitable for determining accurately the rela- 

 tive proportions, but approximately the monoclinic and tri- 

 clinic forms aj^pear to be about equal in amount. One triclinic 

 form is well zoned with moderately broad twinning, while a less 

 common type has exceptionally fine twinning, often of the pericline 

 type, and Avith undulose extinction, indicating probably anortho- 

 clase. The ferro-magnesian mineral is sparsely represented in No. 

 98, and in the Bruthen type. It is partly chloritized. but in the 

 former it is green hornblende, and in the latter it appears to 1>p a 

 greenish brown biotite. No analyses have been made of tliese rocks, 

 but it is probable that they would correspond fairly closely with 



