BY G. H. HALLIGAN. 633 



is concerned. In fact, it may be laid down as a rule that, on 

 this coast, the wind per se has no effect on the movement of 

 beach-material. It may accelerate or retard the littoral current, 

 and thus influence the formation of sandbanks and shallows, but 

 as a factor in the determination of the position of a river outlet, 

 or in the modification of a lagoon entrance, its effect is negligible. 



We may now consider in detail each of the river-entrances on 

 the coast, where the tide is blocked by moving sand; and see how 

 that movement affects the navigable width, sometimes moving it 

 to the north and sometimes to the south. 



Commencing at the most northern point of the coast, and 

 travelling south, the first river we meet with is the Tweed. 

 Admiralty Chart No. 1028 shows this entrance to be just south 

 of Danger Point, and two miles north of Danger Reefs. The 

 littoral current is here shown to have a velocity of two knots at 

 four miles offshore, and with strong ripples outside the reefs. 

 The beach trends away to the north-west from Danger Point, 

 and it is evident that Fig. 1 illustrates fairly well the state of the 

 current, and the probable movement of the sand in this locality. 

 Danger Point is not sufficiently concave on its northern side to 

 cause a counter current, but it extends sufficiently far into the 

 ocean to cause a deflection of the current as shown on the plan. 

 When this deflected current meets the Danger Reefs and Cook 

 Island, part of it is again deflected to the north, and forms a 

 counter current along the beach, causing the sand to travel 

 northwards, and thus compelling the Tweed River to discharge 

 its waters on the southern side of Danger Point. 



Byron Bay. — The next important headland is Byron Bay, and, 

 being the most easterly point of Australia, it extends well out 

 into the current. Its northern side is concave, so that Fig. 1 

 represents the current-effect we might expect, and which we find 

 to exist. The counter current along the beach forces Belongil 

 Creek northwards until it meets a rocky patch which prevents 

 further progress. The sand-travel due to this current is sufficient 

 to completely block the entrance to this small creek, and it is 

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