BY W. N. BENSON. 497 



particular, the area of the Lower Tuff -breccias is so full of intru- 

 sions of dolerite, that it is, in all probability, much disturbed. The 

 uppermost member of this Series, in the Bowling Alley Point dis- 

 trict, lies directly below the Nundle Series, the southern equivalent 

 of the Barraba Beds. It is interstratified with thin beds of chert 

 and shale, contains Lepidodendron australe and radiolaria, and, in 

 microscopical structure, is very similar to the rock of the Baldwin 

 agglomerate, but more finely granulated. The Upper, Banded 

 Cherts are also interstratified with tuff, showing very peculiar 

 relations with it. Occasionally there are small lenses of limestone, 

 and numerous flows of spilite; one of which is very continuous, 

 and several hundred feet thick in one place. The limestones are 

 intermittently developed, generally in one horizon associated with 

 spilite and breccia. The Lower Cherts and Breccias are similar to 

 those above, but are more free from spilite in the Bowling Alley 

 Point region. It is not yet clear how far the Upper Series is dis- 

 tinct from the Lower Series, or may be a repetition of it. 



The section at Tamworth, described by Messrs. David and Pitt- 

 man, commences at the top of the Lower Breccias, and includes the 

 remainder of the Series. For this, they give a thickness of 9,260 

 feet, or about the same thickness as the whole of the Bowling Alley 

 Series. The dip, which is very steep at Bowling Alley Point and 

 Tamworth, lessens at Attunga; and the great thickness (1,000 feet 

 or more) reported for the Moor Creek limestone, is probably incor- 

 rect. The widening of outcrop is due chiefly to change of dip. The 

 limestones of Tamworth and Moor Creek are really a repetition, by 

 folding and faulting, of the main line of limestone, which passes 

 northwards from Moonbi to the higher part of Attunga Creek. 

 Beyond this, it appears to pass into the eastern side of the serpen- 

 tine-belt, and may be traced northwards to the latitude of Crow 

 Mountain. Probably the continuous band of limestone, from Bin- 

 gara to Warialda, belongs to this horizon. The fact that the grey, 

 even medium-grained, andesitie tuff, so common in the Nundle- 

 Barraba Series, is absent from the Tamworth Series in its typical 

 form, is often a useful distinguishing feature. 



37 



