174 



E. C. ANDREWS. 



beaches in the neighbourhood and with the hinterland of 

 the subject beach. 



The highest sand dunes of Lady Robinson's Beach rise 

 about 25 feet above the average height of the bay, and 

 these overlook the series of long sandridges and flat troughs 

 which rise about 15 or 17 feet above the bay level and 1000 

 to 1400 yards in width. 



Similar sand flats about 12 or 15 feet above sea level, and 

 modified in places by sand ridges rising to accordant heights, 

 tie various recent islands together around Sydney. On the 

 seaward edge of these flats, high sand dunes have been piled. 



Fig. 3. — Diagram of shoreline forms near Long Reef. 



ABC = a well-subdued profile of sapping. CE = subhorizontal terrace 

 of erosion in gently-dipping rocks. G = Low water mark. 



High cliffs of sandstone, dipping gently inland, occur 

 around Sydney. At Long Reef and Narrabeen the cliffs 

 are subdued and are formed of sandstone and other rocks 

 dipping somewhat gently to the south-south-west. Under 

 these cliffs horizontal ledges of sandstones occur, never- 

 theless such ledges transgress the bedding planes of the 

 sandstones, thus shewing that the surfaces of the ledges 



