PAPERS READ IN SECTION C 



1.— A PRESENT REVIEW OF THE TERTIARIES OF AUSTRALIA. 

 By G. B. PRITCHARD. 



2.— A PRELIMINARY ACCOUNT OF THE GEOLOGY OF NUNDLE 

 DISTRICT. NEAR TAMWORTH, N.S.W. 

 By W .N. BENSON, B.Sc. 



Part 1. — The Geology of Nundle. 



NuNDLE lies near the head of the Peel River, 37 miles south-south- 

 east of Tamworth, and towards the southern end of the great 

 serpentine belt of New South Wales. Though of cons-iderable 

 geological interest and complexity, it has so far escaped detailed 

 study. 15 19 35 



The Devonian System forms the foundation of the whole district 

 and is of very great thickness. It is most convenient to divide it 

 into three sections, which, commencing with the oldest, are re- 

 spectively the Woolomin Series, the Bowling Alley Series, and the 

 Nundle Series. The Woolomin Series forms the eastern portion 

 of the area studied. It consists of steeply- dipping slaty rocks, 

 usually inclined to the east, and striking on the average about 20° 

 west of north. Sometimes rather tuffaceous bands appear and 

 also andesites, but whether these are interbedded flows or intrusive 

 is not yet quite certain. The most remarkable feature is the occur- 

 rence of several parallel bands of red jasper, which are continuous 

 over long distances, but are not as a rule much above 100 feet in 

 thickness. Towards the southern end of the area the series passes 

 up into felspathic quartzites and pinkish felspathic sandstones, and 

 in places is conglomeratic. The series must be several thousand 

 feet in thickness, though it is probable repetition of the beds by 

 overthrust faulting may have occurred. Their lithological 

 uniformity, however, prevents this being readily recognisable. It 

 has been suggested^ that this series has been thrust over the one 

 succeeding it on the west, and there is considerable evidence in 

 support of the hypothesis. The Bowling AUey Series is also of great 

 thickness, and here there is sufficient variety in the formation to 

 allow it to be ascertained that there is little probability of extensive 

 repetition by faulting in the series. Minor repetitions, however, 

 may be fairly common. The strike of the beds is parallel to that 

 of the Woolomin Series, but the dip is predominantly to the west, 

 being nearly vertical in the eastern portion. The order of deposition 

 appears to have as follows : — A thin layer of banded radio- 

 larian chert, on which lies a huge thickness (1000 feet or more) of 

 coarse, grey-blue andesitic tufi, since silicified, containing angular 



