Vol. 55.] ON PALEOZOIC EADIOLAEIAX EOCKS m N. S. WALES. 37 



District of 'New South Wales is now explained by tlie 

 fact that they are almost wholly formed of marine micro- 

 scopic organisms. 

 (5) That the age of the rocks at Tamworth, judged from the 

 macroscopic fossils, is probably either Middle or late De- 

 vonian, or possibly even Lower Carboniferous. That the 

 Barraba and Bingara radiolarian rocks of New South Wales 

 are probably homotaxial, and that those of the Jenolan 

 Caves may be somewhat older, perhaps Lower Devonian or 

 Upper Silurian. 



Our thanks are especially due to Mr. Donald A. Porter, of Tam- 

 worth, for much information regarding the geology of Tamworth, as 

 well as for personal help and guidance; to Mr. G. W. Card, P.G.S., 

 for petrological observations ; and to Mr. W. S. Dun, Assistant 

 Librarian and Palaeontologist to the Geological Survey of New South 

 Wales, for references to literature relating to the radiolaria. 



EXPLANATION OF PLATES II-VIL 



Plate IL 



Geological sketch-map of the parish of Tamworth (N.S.W.), on the scale of 

 1 inch to the mile ; with a key-map showing part of the Colony of New South 

 Wales. 



Plate IIL 



Section near Tamworth (N.SW.)- Showing the occurrence of the radio- 

 larian rocks and their relation to the Devonian coral-limestone and to the 

 Le^idodendron australe-heds. 



Plate IV. 



Section of submarine acidic tuiFs and radiolarian shales of Middle (?) Devonian 

 age, exposed in cuttings on the Great Northern Railway', near Tamworth 

 (N.S.W.). Section approsimately from west-north-west to east-south-east. 



Plate Y. 



Radiolarian claystones, near Tamworth (N.S.W.), dipping west 20^ south 

 at 52°. Probably Middle Devonian. 



Plate VL 



Laminated and contorted radiolarian chert in submarine acidic tuff. Section 

 on the Great Northern Eailwaj, near Tamworth (N.S W.). 



Plate VIL 



Eadiolarian cherts, with submarine tufis crushed into them. Quarry on 

 Tamworth Common (N.S.W.). 



[For Discussion, see p. 64.] 



