BY E. C. ANDREWS. 825 



Plate xlii. — Pittwater (Lower Hawkesbury), illustrating drowned valleys. 

 Post-Tertiary subsidence. Photo by A. E. Dyer. 



Plate xliii. — View of the Lithgow Peneplain, showing the canon cut by the 

 Port Hacking River, and the later drowning of the same. Photo 

 by A. E. Dyer. 



Plate xliv.— Map of Sydney district, showing extent of recent alluvium, 

 deposited during recent subsidence and exposed by more recent 

 elevation. Drawn by M. Morrison. 



The stippled area shows the area occupied by recent alluvium as mapped 

 by Mr. M. Morrison. 



The area indicated by hatching shows recent alluvium mapped by Prof. 

 David. 



The influence of a current from the South is shown by the characteristic 

 disposition of the Narrabeen type of bar. 



