SHORELINE STUDIES AT BOTANY BAY. 167 



squarely, but reach the northern point about a minute 

 earlier than the southern one. The small cuspate fore- 

 lands which break up the otherwise simple curvature of 

 the southern portion of the beach experience the breaking 

 of the wave a little before those portions which lie immedi- 

 ately to the north. With these insignificant local excep- 

 tions, the wave, as it is traced southwards, may be said to 

 lag behind the northern portions in a uniform manner, the 

 rate of travel from north to south, however, of the inter- 

 sections of the breaking wave with the beach being very 

 great. 



Cusps or Scallops— It was noted that during periods of 

 strong local north-east and south-east winds, or indeed, of 

 winds which acted along rather than at right angles to the 

 beach, that neither beach cusps nor scallops were formed, 

 but instead of such forms, a smooth beach was made with 

 a ledge of erosion marking the maximum advance of the 

 waves, 1 the position and height of the ledge depending 

 upon the strength of the wind and the height of the high 

 tide. The influence of a strong local wind upon a heavy 

 ground swell was insignificant, however. While a heavy 

 storm was at its height no scallops were seen. The heavier 

 the storm on Lady Robinson's Beach, the flatter the beach 

 and the higher was it piled in its central portions. Directly, 

 however, the maximum strength of the waves had gone, 

 the beach became scalloped with cusps, the sizes of which 

 were approximately proportional to the heights of the 

 waves. The larger axes of these cusps varied in direction 

 according to the direction of approach of the storm waves 

 and the direction of the wind, but it was always noted that 

 the cusps were arranged in sets, and that these sets had a 

 definite relationship to the configuration of the beach. Thus 

 the main southern salient was only once observed to have 



1 Andrews, E. C, Op. cit. 



