THE PHYSIOGRAPHY OF BOTANY BAY. 121 



of its vicinity to Sydney and the ease with which it may 

 be inspected, and the statements made in this paper verified 

 by any member who cares to spend a short day on this 

 interesting work. A visit to Kurnell and a short walk to 

 the top of the hill near the Trigonometrical Station, 

 "Solander," enables one to obtain a panoramic view of the 

 district described. 



It will at once be seen that the dominant feature is the 

 very large area of sand which fringes the shore line on the 

 northern, western and southern sides of the bay, and 

 extends inland as shown by the stippled area on the accom- 

 panying map (Plate V). The edge of the sand furthest 

 from the existing shore-line shows approximately the 

 boundary of the old rocky coast of Trias-Jura sandstone, 

 possibly at the time the last subsidence, of from 200 to 

 300 feet, took place. 1 



In this paper an attempt is made to solve the problem of 

 how all this sand came here, and why the shore-line has 

 assumed its existing shape. 



There are two streams discharging into Botany Bay, 

 viz: — George's River, having a length of 50 miles, and 

 Cook's River, which is about 11 miles long. The combined 

 catchment area of the two rivers is 339 square miles. 



The course of George's River for the upper 30 miles is 

 through steep rocky gorges in the familiar Hawkesbury 

 sandstone formation. High water level of the ocean is 

 reached about the township of Liverpool, at which point a 

 clam was erected about the year 1830 for the purpose of 

 obtaining a water supply for the residents. It will thus be 

 manifest that any sand coming down George's River will 

 be deposited fn the bed of the stream where the gradient 

 of the river ceases, and before any sand can arrive at 



1 David, T. W. E., b.a., d.sc, f.r.s., Anniversary Address to the Royal 

 Society of New South Wales, May 1896, this Journal, Vol. xxx, p. 57. 



