BY H. I. JENSEN, D.SC. 165 



The progressive increase of folding in Permo- Car- 

 boniferous rocks observed on going north from the Vic- 

 torian to the Queensland border, reaches its climax in the 

 Macleay-Manning and Southern New England districts 

 of Xew South Wales. North of the Macpherson Range, 

 the Permo- Carboniferous have only been materially dis- 

 turbed in certain senkung&feldt areas of small extent. 



At Bega, in N.S.W. {see Fig. 11), we have the Ordovician 

 rocks and igneous rocks of granite composition. Further 

 north, in the Cobargo district, lightly folded Silurian shales 

 (Xarira, schists) rest on the Ordovician. Still further 

 north, not far from the Narrigundah goldfields, Devonian 

 rocks appear, according to Anderson [16], sitting horizon- 

 tally on top of folded Silurian. These Devonian rocks 

 are seen at Braidwood and Ettrema, folded into huge 

 anticlines and synclines. At Sassafras, horizontal Greta 

 and Ui)per Marine rocks rest on them. That is the case 

 in the Turpentine Range, Sassafras, the headwaters of 

 the Clyde, Endrick and Danjera rivers. [17] 



Still further north, as at Sydney and Maitland, the 

 Permo- Carboniferous is lightly folded, and horizontal 

 Triassic caps it. Still further north, on the Macleay and 

 Manning Rivers, the Permo- Carboniferous is greatly folded. 

 After that the intensity of fold movements diminishes 

 progressively as we go north into Southern Queensland. 



These facts may be stated in geological parlance in 

 this w?y — 



Sydney was the centre of a great geosyncline, the 

 Bega-Monaro district and the Macpherson Range were 

 the stable and resistant hinges [13] during all periods 

 up to the Permo- Carboniferous. As sedimentation con- 

 tinued in the Xew England subsidence area during the 

 Permo-Carboniferous, the uplift of this province took place 

 in the Triassic. During the coal measures period, therefore, 

 the centre of the geosyncline was near Sydney. East and 

 west folding has taken place in the same way, Sydney 

 being the centre of the depression. {See Fig. 11), 



During the subsequent Triassic period, the Permo- 

 Carboniferous sediments were folded in subsiding areas, 

 and eroded away in other areas. 



The synclinal nature of the Sydney basin closed with 

 the Triassic period of sedimentation. 



