THE 



Transactions 



OF 



The Royal Society of South Australia 



(Incorporated.) 



Vol. XLIV. 



The Igneous Rocks of encounter Bay, 

 south australia. 



By W. R. Browne, B.Sc. 

 (Communicated by Professor Walter Howchin.) 



[Read November 13, 1919.] 



' Plates I. to IV. 



Contents. 

 I. Introduction. 

 II. Coastline Physiography. 



III. General Field Relations of the Igneous Rocks. 



(1) Granite Island. 



(2) Rosetta Head. 



(3) Port Elliot. 



IV. Petrography. 



(1) Porphyritic granite. 



(2) Quartz mica diorite. 



(3) Even-grained granite. 



(4) Albite mica syenite. 



(5) Red (potash) aplite. 



(6) Minor* potash aplites, etc. 



(7) Soda aplite. 



(8) Greisenised soda granophyre. 



(9) Uralitic dolerite. 

 V. Petrogeny. 



(1) Genetic relationships of the rocks. 



(2) Mineralogical variations. 



(3) Discussion of the variation diagram. 



(4) Shape and nature of the intrusion. 



(5) Mechanics of differentiation. 



(6) Comparisons with similar rocks elsewhere in the 



State. 



