320 THE BONDI ANTICLINE. 



of all sizes up to twenty feet in diameter, embedded in the sand- 

 stone in the most confused manner"; also rounded pebbles of 

 shale "usually ovalin shape and embedded in such a manner that 

 the longer axis of the pebble is nearly always inclined, or dips 

 towards the South-west." Tn his matured opinion, these i-oeks 

 were broken and pushed by the movement of ice.* 



Contorted beds at Coogee were figured and described by Prof. 

 David, t who accepted Mr. Wilkinson's explanation that the dis- 

 turbance was caused by the grounding of contemporary icebergs. 

 Objections to this theory were raised by the Rev. J. E. Tenison- 

 Woods,i who contended that the usual accompaniments of ice- 

 action, such as transported and engraved stones, moraines, till, 

 glacial mud, or boulder clay, are here absent. He considered 

 that the breaking and scattering of the sliale might have been 

 accomplished b}- the floods of contemporary streams. 



Mr. R. D. Oldhamll was not convinced that the evidence ad- 

 vanced by Mr. Wilkinson proved the presence of glaciers. 



Neither afloat nor aground does ice work thus. Transported 

 rocks, so constant a feature of ice, and so easy to detect, are 

 absent here. It is now submitted that neither ice-action nor 

 contemporaneous denudation satisfactorily explains the crushed 

 shales. On the contrary, it is thought that their injuries were 

 received when they were caught in the press of the Bondi anti- 

 cline, and ground lietween moving masses of sandstone, and that 

 the disturbances arose from a series of thrusts and folds started 

 in the yielding and quaking mass by the advancing anticline. 



From an economic point of view, it will be of importance to 

 consider if the coal-deposits in this area have deteriorated by 

 crushing. 



The dune-and-pond origin of the Hawkesbury Sandstone, so 

 ably advocated by Tenison-Woods, would be favoured by the 

 withdrawal of the ice-hypothesis. 



* Wilkinson, Mem. Dept. Mines, Pal. iii., 1890, p. 28, footnote. 



t David, Quart. Journ. Geol. Soc, xliii., 1887, pp. 190-196. 

 Ten. -Woods, Proc. Roy. Soc. N. S. Wales, xvi., 1882(1883), p. 75. 

 II Oldham, Rec. Geol. Survey India, xix., 1886, p. 43. 



