BY W. N. BENSON. 325 



V. Upper Bowling Alley Tuffs and Breccias, with some cherts. 

 With these are two lenses of limestone considerably west of the 

 main zone. 



vi. Mudstonesof the Nundle Series, gradually passing up from 

 the cherts associated with the Upper Breccias and including a 

 conglomeratic zone which forms Nundle Sugar Loaf, two miles 

 west of the township. 



In putting forward this sequence, it was noted that there 

 seemed a possibility of considerable repetition occurring within 

 it. The distinction between the phyllites and jaspers east of 

 the serpentine (the Eastern or Woolomin Series), and the rocks 

 to the west of it, seemed very clear. 



In the Tam worth District, however, further facts were dis- 

 covered. Parts of the Eastern Series were recognised as being 

 merely infolded and highly crushed equivalents of western rocks, 

 and the Western Series itself was subdivided as follows (6): — 



(a) The Lower Middle Devonian series of radiolarian cherts 

 and claystones, with intercalated tuffs containing the Nemingha 

 Limestone, which is often closely associated with a very ferru- 

 ginous tuff or agglomerate. 



(b) The Igneous Zone, consisting chiefly of breccias, agglomer- 

 ates, and tuffs with dolerites and spilites. 



(c) An Upper Middle Devonian Series of radiolarian cherts 

 and claystones, containing, in its lower part, the Loomberah 

 limestone, and, in its middle or upper part, the Moore Creek 

 limestone. In the portion of this Upper Middle Devonian Series 

 which lies above the Moore Creek limestone (as, e.g., the clay- 

 shales of Tam worth Common), the cherty character of the sedi- 

 ments is entirely lost. 



(d) The Baldwin Agglomerates, which form the base of the 

 Upper Devonian Series. 



(e) The Barraba Mudstones, forming the Upper Devonian 

 Series proper. These are often difficult, indeed impossible, to 

 distinguish lithologically from the rocks of the upper portion of 

 the Upper Middle Devonian. 



It was further shown that there are several repetitions of zones 

 (a) and (6) in the region lying immediately west of the Serpen- 



