178 GEOLOGY OF QUEENSLAND COAST, 



examples of drowned topography occur in the neighbourhood of 

 Hinchinbrook Island, also inaST.S. Wales in the vicinity of Port Jack- 

 son and Hawkesbury River. To the south of Queensland longer 

 continued marine erosion during periods of more stable equilibrium 

 is shown by the cliffs of Sydney district, Victoria and Tasmania. 

 (This after pronounced movement or movements of depression.) 



The existence of islands like Frazer, Moreton and Stradbroke, 

 and widespread extensive coastal plains of the Queensland area, 

 the tombolos* of the shelf islands, the lagoons and lagoon-marsh 

 meadows, the bay bars, etc , all point to the adolescent and late 

 adolescent stage of development attained by the Queensland coast. 

 These features are necessarily more accentuated south of the 

 Barrier owing to the increased wave-action in Extra-Barrier 

 areas. When the harbours of the coast become silted uj^, the 

 headlands cut back, and the sea able to carry out its intention of 

 establishing a straight or gently swinging shore line, then will the 

 coast have advanced to maturit}''. That period is far away at 

 present, although even this stage has been attained in certain 

 small areas, seeing that elevation has accelerated the movement. 

 The straight eastern shore-line of Frazer Island is suggestive of 

 maturity for that particular spot. Here, however, the sea has 

 had a sand mass only to work on. 



The situation of Frazer Island, the distribution of the great 

 coastal flats, the deflection northwards of such streams as the 

 Brisbane, Tweed, Clarence, Richmond and Macleay, points to a 

 dominant along-shore current from the south, and a weak fluvia- 

 tile action. The streams, in their attempts to push their loads off 

 shore, are opposed by a stronger wave action which piles up river 

 bars; a dominant current redistributes the debris along its own 

 path, offsets and overlaps occur, and finally the stream is deflected 

 for miles out of its normal course. 



The occurrence and present aspect of the aoastal plains and 

 allied features at heights above sea level argues a general elevation 

 in historic times for the coast line itself. 



* A sand bar connecting two islands, or islands with mainland. Gulliver 

 " Shoreline Topography." Proc. Am. Acad. Arts & Sci., 1899, xxxiv. 



