36 



porphyritic granite. Further, Mr. Tilley has reported (27) the 

 occurrence at Cape Willoughby, Kangaroo Island, of rutile- 

 bearing albitites closely associated with potassic granites and 

 connected with them by the common link of the opalescent 

 quartz. As these Cape Willoughby rocks constitute another 



I 



MaS^-""'^^ 



"^--/ 



-5.10^.260% J 



^ 



^"^^W-^ 



_iS^o_— ^--^ ' 



•^■'^^ 







-^ 



^^^-^^ ' 



h- I:;:;:::::^^ 





^ -^oj^^^^--.^ ~~" 



- — ~~—Jko^ 



^^^^^^^r^-- 



TjOp 



Izr— ^-. ^^--j 





=-— - — . 



(/) 2-71$ 



Specific Gravities 

 Fig. 4. 



(3;e-6/5 



facies of the Encounter Bay magma, the connection of the 

 Rosetta Head syenite with the granite magma is again 

 indicated. As pointed out above, the syenite is to be con- 

 sidered as an end product of differentiation, the last member 

 of the series which includes the diorite and the two granites. 



(27) C. E. Tilley: loc. cit. 



