[Proc. Roy. Soc. Victorta, 32 (N.S.), Pt. I., 1919]. 



Art. VII. — The Diabases and Associated Rocks of the Howqua 

 River near Mansjield, witli reference to the Heathcotian 

 Prohlemi in Victoria. 



By E. O. TEALE, D.Sc, F.G.S. 



With an account of the Petrography of the Diabases by 

 Prof. E. W. Skeats. 



(With Plate IV., 4 Text Figures and Map). 

 [Read July 10th, 1919]. 



Contents. 



1. Introdiiction. 



2. Position and Access to the Howqua Re^uon. 



3. Physiographical Features. 



4. General Geology. 



5. Lower Palaeozoic Rocks (Heathcotian to Silurian). 



A. Diabases : — 



(a) Normal Diabase. 



(b) Soda Rich Diabase. 



(c) Platy Diabase. 



B. Tuffs and Agglomei-ates. 



C. Alteration features of the Diabase : — 



(a) Red Jasper. 



(b) Siliceous — cax'bonate rocks. 



(c) Talc rocks. 



(d) Serpentine and Chrysotile. 



(e) Mineralization of the Diabase— Auriferous sulphides, etc 



D. The Sediments : — 



(a) Tlieir Lithological features. 



(b) Apparent structural relationships. 



(c) Phosphatic Deposits. 



E. Concerning the Age of the Diabase and Cherts — a comparative 

 review. 



6. The Upper Palaeozoic Rocks. 



A. Devonian : — 



(a) Dacite-porphyry. 

 ^b) Grano-diorite. 

 (c) Diorite. 



B. Lower Carboniferous : — 



(a) Basal conglomerates. 



(b) Rhyolite. 



(c) Conglomerate. 



(d) Sandstones. 



(e) Purple shales. 



7. Summary and conclusions. 



1 



