BEACH FORMATIONS AT BOTANY BAY. 181 



alongshore from N. to S. at average rate of from 8 to 10 

 minutes a mile. 



Deductions. 

 The heavy onshore winds of Sydney are from the south- 

 east quadrant. When the heaviest and most continuous 

 winds blow from the south-east, the rain is also generally 

 heaviest and the sea is also piled up in a measure against 

 the land to increase the tidal range. The heavy waves 

 enter Botany Heads and advance across the bay to Lady 

 Robinson's Beach. Although they enter the bay at various 

 angles, nevertheless they break on the beach in such a 

 manner that such breaking wave travels alongshore from 

 N. to S. at a rate of from three to six miles an hour. 

 From a study of the beaches of Sydney it is evident that 

 the main beach outlines have been determined by record 

 storms, 1 while the weather of interstorm periods appears 

 to be capable only of modifying the flood or storm profiles. 

 Thus the north and south points of Lady Robinson's Beach 

 have been determined as to their main features when 

 onshore winds, waves and stream activities have joined their 

 maximum forces. The small foreland at the entrance to 

 Cook's River is a compromise between the flow of the river 

 when in high flood and of the storm waves from the east, 

 coupled with the current generated alongshore by the storm 

 wind and waves. Similarly for the sandy foreland (Doll's 

 Point) forming the southern horn of Lady Robinson's Beach 

 at the entrance to George's River. The two or three small 

 intermediate blunt-nosed forelands at the foot of President 

 Avenue and one mile farther south, for example, arise from 

 the interaction of waves and currents from both ends of the 

 Day. These points have been formed on the seaward aspect 

 of the bay bars which emerged from the waters of the bay 

 possibly not longer since than several hundreds of years. 



1 E. C. Andrews, (reocrr .^aical Significance of Floods, Proc. Linn. 

 Soc. N.S.W., 1906, p. 828. 



