president's address. 573 



E.S.E.* At Chaiters Towers the strike of the Pre-Devonian 

 quartzites, greywackes, slates, and shales has been carefully 

 determined to be N.W. and S.E., the rocks being folded. f At 

 the Gilbert tlie Pre-Devonian slates strike W.N.W. to W.S.W.J 

 At Peak Downs foliated and contorted micaceous and hornblende 

 schists (Pre-Devonian ?) strike N.E. and S.W. The last-mentioned 

 locality is on the line of strike of the great line of folding, which 

 may be termed the Adelaide Axis, trending from St. Vincent's 

 Gulf to Broken Hill and thence through Girilambone north-east- 

 wards. The dominant strike of the Pre-Devonian schists in 

 Queensland and of their axes of folding lies between N.W. to 



^Y.N^Y. 



As regards the date of the folding of the Upper Silurian strata 

 in Tasmania, it must have antedated the Permo-Carboniferous, as 

 the latter are not folded. The Upper Silurian rocks in Tasmania 

 are not seen in contact with Devonian strata, the existence of this 

 system not yet having been proved in that island. 



In Victoria a considerable amount of folding of the Upper 

 Silurian rocks took place before the Middle and Lower Devonian 

 rocks were formed. § 



In New South Wales the folding antedated certainly the close 

 of the Devonian or commencement of the Carboniferous Period, 

 and the folding of these Upper Silurian strata was probably the 

 chief factor in the production of the southern portion of the Main 

 Dividing Range in New South Wales. 



In Queensland the folding of the Pre-Devonian rocks took 

 place for the most part in Pre-Devonian time. 



IV. Devonian. 



No rocks of undoubted Devonian Age have as yet been deter- 

 mined in Tasmania or in South Australia, but in Queensland, 



* Jack and Etheridge — Geology and Palasontology of Queensland and 

 New Guinea, 1892, p. 20. 



t Loc. cit. p. 27. 



X Loc. cit. p. 29. 



§ f. Murray, loc. cit. p. 56, and plate facing p. 51. 



