PRESIDENTIAL ADDRESS. 53 



the Lower Cambrian of South Australia. In Northern 

 Territory the Cambrian strata are folded and faulted onN.W. 

 to S.E. lines, while the Ordovician rocks are tilted in a 

 S.W. to S. direction. 



Iq Silurian time the west-Tasmanian, the Melbourne 

 Lilydale and other basins in Victoria were folded on N.N.W. 

 lines. In the Monaro-Bathurst Tableland of New South 

 Wales the folds strike mostly W. of N. and E. of S., 

 without pronounced overfolding. In the Forbes and Cobar 

 areas the folds swing around to E. of N. and W. of S., 

 conforming more to the Broken Hill lines. At Chillagoe 

 the Silurian strata are folded on E.S.E. to W.N.W. lines. 



In Devonian time, in the Victorian areas, there is a slight 

 tendency for the folds to fan out or virgate north of the 

 Tasmanian V. On the upper Murrumbidgee near Burrin- 

 juck, they strike north north-westerly, and are uncom- 

 formable to the Silurian strata though folded on the same 

 lines, the folding being from W. to E. At Yalwal they 

 strike N. by E. and S. by W. Along the S.W. portion of 

 the Blue Mountain area of New South Wales the Devonian 

 rocks are folded sympathetically with the main axis of the 

 trough of the great coal-field. There is a tendency for 

 these strata to be overfolded inwards towards the centre 

 of the trough. In the New England area the Devonian 

 rocks still preserve a N.N.W. to N. 30° W. strike with a dip 

 towards the trough of the coal basin. In the Burdekin 

 Basin of Queensland the Middle Devonian rocks are folded 

 on north-easterly lines, In the Ord River region of the 

 Kimberley District of West Australia they describe an 

 arc with its convexity directed southwards. 



Carboniferous. — In Victoria, in the Avon and Mansfield 

 districts the rocks are folded on N.W. to S.E. lines. In the 

 Grampians area the strike is more meridional. In New 

 South Wales the Carboniferous rocks form a selvage to the 



