BY W. N. BENSON. 577 



on a very viscous magma, during and after its consolidation. At 

 the same time one must note as a fact at present without ex- 

 planation, tlie very considerable resemblance between these acid 

 quartz-keratophyres, and the veins of quartz and albite, that 

 occur in the serpentine in other parts of the Serpentine-Belt 

 (see 16, p. 691). 



Barraba Series (of Upper Devonian age). 



Two divisions of the Upper Devonian Series are recognised; 

 the lower is the Baldwin Agglomerates, and the upper the 

 Barraba Mudstones. This is in conformity with the classifica- 

 tion adopted in the first part of this series(14). However, since 

 the lower agglomerates are frequently not developed, it seems 

 best to extend the term Barraba Series to comprise the whole of 

 the Upper Devonian formation, and to recognise the Baldwin 

 Agglomerates merely as a basal zone, which may or may not be 

 present. Both divisions occur in the Tamwortli District. We 

 commence with the discussion of the agglomerates. 



It was stated in a previous paper(14, pp. 500-1) that the coarse 

 agglomerates did not, as was previously supposed, rest unconform- 

 ably on the banded claystones of what is now termed the Upper 

 Middle Devonian Series, where they are exposed on the bills about 

 Cleary's Selection, to the north-east of the Tamworth Common. 

 The inference was drawn chiefly from a consideration of the litho 

 logical similarity between the matrix of the agglomerates, and the 

 tulfs and breccias in the underlying Middle Devonian, as well as 

 the overlying Upper Devonian rocks, and the criteria for the litho- 

 logical proof of a conformity through continuous oscillatory 

 change of condition, were discussed from a hypothetical point of 

 view. This conclusion can now be thoroughly substantiated on 

 stratigraphical grounds. The coarse agglomerates may be traced 

 round the face of the hills from the Two-Mile Bridge, on the Peel 

 River, south-east of Tamworth, until they meet the fault in SjDring 

 Creek, on the northern boundary of the Common. The boundary 

 of the agglomerates is at every point, in complete conformity with 

 the strike of the Middle Devonian rocks, on which they rest. Par- 

 ticularly clear proof of this, is afforded by the sections exposed 



