703 



NOTE ON THE RELATION OF THE DEVONIAN AND 

 CARBONIFEROUS FORMATIONS WEST OF TAM- 

 WORTH, N.S.W. 



By L a. Cotton, B.A., B.Sc, Assistant Lecturer and Demon- 

 strator IN Geology, University of Sydney, and A. B. 

 Walkom, B.Sc, Linnean Macleay Fellow of the Society 

 in Geology. 



(Two text-figures.) 



The following notes are the result of observations made by us 

 during a cycling trip from Tamworth to Mudgee, via Gunnedah 

 and Coonabarabran, with the object of examining the strata. 



The geology of the Tamworth-end of the section examined, has 

 been discussed by Professor David and Mr. E. F. Pittman*, who 

 have shown the characteristic rocks to be interstratified radiolarian 

 cherts and tuffs, with occasional bands of limestone. They have 

 also shown that, as a result of tectonic movements in the district, 

 the strata have been folded into a sharp anticline between Moonbi 

 and Tamworth, and they have indicated the position of a probable 

 fault, with a throw of 9,000 feet to the east.f 



Our section (Fig. 2) is a continuation of that given by Professor 

 David and Mr. E. F. Pittman, and extends to a point three miles 

 west of Gunnedah, the section being taken along the road. It is 

 built up from dip and strike observations made, where possible, in 

 the road-cuttings. These are represented on the map. Unfortu- 

 nately, relatively few of these were obtainable, on account of the 

 extensive development of recent deposits. These consist chiefly of 

 surface-alluvials, and one large bed of river-gravels, at least 60 

 feet thick, containing pebbles about 3 or 4 inches in diameter, 

 which extends four miles on either side of Somerton. 



* " On the Palaeozoic Radiolarian Rocks of New South Wales," Q. J.G.S., 

 Vol.lv., 1899, pp. 16-37. 



t Op. cit. , Plate 3. 



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