PRESIDENTS ADDRESS. 13: 



These features indicate the approaching limit of sediment. 

 Wherever the profile of the New South Wales coast be examined, 

 a terrace is found to project from the beach to the hundred-fatliom 

 line, whence the ground quickly changes to a steeper grade. 

 Compared with most other coasts, the continental shelf is here 

 exceptionally narrow, resembling in this respect that of Western 

 South America. Off Cape Dromedary the shelf contracts to a 

 dozen miles, and off Newcastle it broadens to thirty-four. This 

 narrowness of the shelf renders it impossible that extensive 

 trawling grounds may be discovered in the waters of our State, 

 The continental shelf of New South Wales is described and con- 

 trasted with that of Queensland by Dr. H. B. Guppy.* 



Working across the shelf with dredge or trawl, the bottom 

 proves rough and rocky upon the shallower inshore half. Out- 

 side Sydney the projecting reefs are the favourite resort of the 

 schnapper, and their positions are known to the fishermen by 

 cross bearings. But in the outer portion the rocks disappear 

 and the bottom is found to be a smooth even floor of sand and 

 mud, a plain of sedimentation. Geologists have collected con- 

 vincing evidence of recent submergence of this coast. f So that 

 it is likely that the rough inshore part of the shelf within forty 

 or fifty fathoms I'epresents an old denuded land surface, including 

 perhaps the stumps of sea cliffs of a former coast-line. In Western 

 Europe river-beds have been traced into the Atlantic for a hundred 

 miles beyond their present estuaries. | Thus we might expect to 

 find submarine gorges crossing the Australian shelf in continua- 

 tion of present valleys. But I am unable to distinguish traces 

 of such among the soundings on the chart, and conclude that if 

 in existence they have been obliterated by sediment. There are 

 indeed some irregularities of the contour lines outside Port Jack- 

 son and Port Stephens, but these may result from the ebb tide 

 eddying from those harbours. 



* H. B. Guppy, Journ. Vict. Inst, xxiii., 1890, p.59. 

 t David and Halligan, Journ. Roy. Soc. N.S. Wales, xlii., 1908 (1909)^ 

 p. 229. 



X Hull, Trans. Victoria Institute, xxx., 1897 (1898), p. 311. 



