166 THE BUILDING OF EASTERN AUSTRALIA 



Prior to the Permo-Carboniferous, the whole of the 

 East Australian Coast was a synclinal. The formatio;i of 

 the Bega-Monaro ge-anticline commenced in the early 

 Palaeozoic, and that of the Macpherson Range commenced 

 in the Permo-Carboniferous. 



To make the position clear, we may regard the move- 

 ment along the whole Australian coast as either a move- 

 ment upwards or a sinking. 



From the point of view of uplift without tangential 

 pressure, the Kosciusko mass has continuously risen since 

 Ordovician times ; proceeding northwards, uplift came 

 later and later, post-Devonian at Narrigundah, post- 

 Carboniferous at Nelligen and Braidwood, post Permo- 

 Carboniferous at Yalwal, Ettrema, etc., post Triassic at 

 Sydney. In the country stretching from Ar mi dale on New 

 England to the mouth of the Macleay and Manning Rivers 

 uplift, accompanied by tangential compression, took 

 place prior to the elevation of the Sydney area, namely 

 in the Triassic period. This uplift was also experienced 

 in Northern New England and the Macpherson Range, 

 but was there only accompanied by tangential pressure in 

 localised subsidence areas. 



Compression is, generally speaking, the outcome of 

 subsidence. When subsidence ceases, earth segments rise 

 without being folded. Small areas lagging behind in the 

 general uplift may undergo compression. Viewing the 

 East Australian earth movements in the sense of downward 

 movements, we see from the above that the maximum 

 subsidence took place in the New England-Manning belt 

 prior to early Triassic, when elevation commenced in this 

 region. 



The Sydney area remained submerged longer — in fact 

 until the Triassic sediments had been laid down, when 

 regional uplift set in ; and south of Sydney the cessation 

 of subsidence came earlier and earlier in geological time. 



The Macpherson Range became a stable or rising area 

 in late Permo-Cabroniferous. 



During Mesozoic times, as well as Tertiary, the general 

 tendency has been towards uplift and tension along the 

 whole east coast of Australia, for the horizontal disposition 

 of a formation of a given geological age may be considered 

 as indicating that subsidence had ceased, or did cease, in 



