14 president's address. 



It is now suggested that the continental shelf of this State 

 owes its profile lo the Notonectian current. A bank so regular 

 in depth and so extensive in length must be of recent geological 

 date. Otherwise diiferential crustai movements, lowering in one 

 place and hoisting in another, would have disturbed its unifor- 

 mity. It is again a fair infei'ence to deduce that, however it is 

 made, this bank is still in the making. Since recent depression 

 of the coast is an accepted fact, it has been deposited since the 

 last subsidence and an older or e\en a succession of shelves may 

 lie buried beneath the present one. The sudden angle of the 

 shelf seems to have suggested faulting to Mr. C. S. Wilkinson, 

 who wrote: "[At] a line about 20 miles east from the precipi- 

 tous coast . . . the bed of the ocean probably . . . has 

 been faulted to a depth of over 12,000 feet."* 



On the Kosciusko Range, long wreaths of snow stretch along 

 the eastern mountain brow through the summer and after all 

 the rest of the winter's fall has melted away. The cause of this 

 snow wreath is the prevailing westerly wind which sweeps off 

 the winter's snow falling on the mountain top and drops it on 

 the sheltered slope where it packs in a talus to a great depth. 

 In such a manner I imagine that the current sweeps sediment 

 along the continental shelf till it is tipped over the edge into 

 quiet waters. A section of the bank thus formed is sliown in 

 the Ulladulla profile; the sedimentary deposit being separated 

 from its conjectured continental base by a white line. 



Neither the irregularities of the land above nor of the base 

 beneath disturb the sweep of the 100-fathom line upon the 

 chart. But east and south of Newcastle and Broken Bajr, 

 whence issue the Hunter and Hawkesbury Rivers, the shelf 

 broadens considerably so that Sydney is past before the shelf 

 retreats to its ordinary breadth. Where the shelf is carried out 

 farther the talus slope beyond is correspondingly longer, just as 

 would be the case in a railway embankment carried along a 

 mountain side. Thus in the model of the coast off Sydney, 



* Wilkinson, Notes on Geology of N. S. Wales, 1887, p. 70. 



