RECENT MARINE EROSION AT BONDI. 157 



Plate VI is shown other boulders of sandstone transported 

 and broken by the waves. These, in their present position, 

 are on a shelf 6 to 10 feet above high water mark and some 

 200 feet from its edge. The one marked A is a remnant 

 of a much larger block, and still weighs from 15 to 20 tons; 

 the white surfaces shown in the photograph are all fresh 

 surfaces produced by the breaking off of large portions, one 

 of which is shown at B. This fragment alone weighs about 

 8 tons, and behind it there are others not visible in the 

 picture. The white scars on the adjoining masses of sand- 

 stone give eloquent testimony of the way in which they 

 were battered by A and B being hurled against and over 

 them by the waves. Similar effects are in evidence at 

 many other points, and to any one familiar with the locality 

 it is obvious that more marine denudation was accomplished 

 above high- water mark during the few hours of this one 

 storm than the cumulative results of many previous 

 years. 



The writer has been a frequent and regular visitor to 

 this and other parts of the coast near Sydney during the past 

 fifteen years, but never before has he seen anything 

 approaching in magnitude the work of wave erosion during 

 this particular storm. It affords ample testimony of the 

 correctness of the principle enunciated by Mr. E. O. 

 Andrews, b.a., that it is the infrequent great storm wave 

 which is the main factor in producing coastal erosion, just 

 as it is the infrequent great flood which is the main factor 

 in river erosion. 



The great boulders transported and broken by the storm 

 of July 1912, will probably rest peacefully in their present 

 position for many years, until another wave arrives of 

 sufficient magnitude to again disturb them from their 

 present position. The photographs used in the illustrations 

 were taken by Mr. J. W. Tremain. 



