261 



PETROLOGICAL NOTES. 



No. ii. The Relations between some Western Australian 



Gneissic and Granitic Hocks. 



By M. Aurousseau, B.Sc. 



The following notes are the results of three visits to Roelands 

 and one to Albany. As I may not be able to resume the work, 

 it is given here as it stands. Detailed mapping was begun at 

 Roelands, but was not carried far enough to be of value. Prac- 

 tically no laboratory-work was done, therefore all rock-names 

 must be interpreted as field-names only. 



The Geology op the Roelands District. 



Roelands, 11 3| miles from Fremantle, on the South- West 

 Railway, stands at the foot of the Darling Range (fault-scarp), 

 east of Bunbury. The surrounding country was examined by a 

 number of traverses between the Collie and Brunswick Rivers, 

 as far east as Shenton Elbow on the former, and Olive Hill 

 Siding on the latter. The formations met with are, in order of 



increasing age- 



Alluvials. 

 Laterite. 

 Conglomerate. 

 Basic dykes. 

 Pegmatites. 

 Gneiss. 



Porphyritic granodiorite. 

 The Alluvials occur all along the foot of the range, and in the 

 Brunswick River Valley, where they are stratified. 



Laterite is sparingly distributed as a capping on the highest 

 hills, about two miles east of the foot of the range. 



An outcrop of Conglomerate, to be correlated tentatively with 

 the Donnybrook Series, occui's as a low hill between tlie railway 

 and the foot of the range, but separated from the range by 



