BY W. N. BENSON. 347 



the quartz-keratophyre breccia, associated with the limestone, 

 described and figured in a previous paper (5, p. 137), belongs to 

 this horizon. In the southernmost extension of the zone, the 

 strong impregnation of the rock by ferruginous solutions, and 

 its consequent red colour, are not always present. 



We find in this another zone, which can be traced all through 

 the Loomberah District, and into the Nundle District. It is 

 also seen, in all probability, in the Tam^\'orth District. The 

 masses of red, ferruginous breccia associated with the southern- 

 most masses of the Nemingha limestone in the south-east of the 

 Tamworth Region, doubtless belong to this zone, and it is a 

 matter of great difficulty to determine how much of the pyro- 

 clastic rocks on East and West Gap Hills in that parish rightly 

 belong to the Nemingha Red Breccias or to the Igneous Zone. 



The Silver Gully Agglomerate. — A short distance westward of 

 this zone, commencing at Black Jack, is a second mass of coarse 

 breccia associated with limestone, which, however, is nearly 

 always in the form of small fragments except on Black Jack 

 itself. This may be traced southwards across Cope's Creek, and 

 obtains a great width in Silver Gully. A small lenticle of lime- 

 stone appears on the slope to the north of this creek. It is 

 apparently heavily faulted near this creek. Beyond Silver 

 Gully, it continues as a narrowing band containing small lenti- 

 cular patches of limestone, but is cut off by a fault before reach- 

 ing Hyde's Creek. 



Though the limestones on this zone are of the Nemingha-type, 

 though in small lenses, the lithology of the breccias, the occur- 

 rence of fragments of coarse dolerite, etc., and the absence of 

 red colouring, are features so distinct fiom those of the Nemingha 

 Red Breccias, that the two masses cannot be considered to be 

 on the one horizon. We may conclude, therefore, that the Silver 

 Gully Agglomerate is a third horizon of pyroclastic rocks, inter- 

 mediate in position between the Igneous Zone and the Nemingha 

 Red Breccias. 



This intermediate horizon appears to be repeated on the 

 hills west of Wallaby Mountain. It commences immediately 

 south of the fault which truncates the keratophyre, and here is 



