592 ALKALINE PETROGRAPHICAL PROVINCE OF E. AUSTRALIA, 



tinguaibe-laccolites; and the Kosciusko nepheline-segirine phonolite 

 described by David, Guthrie, and Woolnough. 



4. In Queensland : The Little Liverpool Range and Fassifern 

 trachyte lavas — The Mt. Flinders mass — The Glass House 

 Mountains and the Yandina-Coolum area — TheYeppoon Ranges. 



It has already been pointed out how all these rocks lie in a 

 definite but somewhat sinuous belt, which only ramifies to a 

 minor extent; and it has been suggested that this belt occupies 

 the position of a long line of fractures. I would further here 

 suggest that these fractures owe their origin to differential 

 movement of uplift and subsidence in adjoining areas, such as 

 gave rise to the elevation of the Blue Mountains (east of the 

 Mittagong-Canoblas-Dubbo line), New England (east of the New 

 England), the Darling Downs (west of the Little Liverpool 

 Range), and the Woodford peneplain (west of the Glass House 

 group). 



B. Age of Intrusion. 



With the exception of the Regatta Point and Kiama-J amberoo 

 areas all the alkaline intrusions investigated so far have been 

 shown to belong to the late Cretaceous or early Tertiary eras. 

 Definite fossil evidence fixes the Warrumbungle mass as early 

 Tertiary. In the other districts no such definite evidence has 

 been discovered as yet, but the alkaline rocks have been proved 

 later than Trias or Trias-Jura, as the case may be, and strong 

 probabilities exist that they belong to the same era as the 

 Warrumbungle mass. 



C. Textural Evidence of Consanguinity. 



(a) In most of the areas mentioned an abundant rock-type is a 

 rather acid, very fine-grained, grey, alkaline lava, often exhibiting 

 fine columnar structure. This rock is sometimes orthophyric, 

 sometimes microgranitic in fabric, and belongs to the Rosenbusch 

 families of comendite and pantellarite. Dyke-varieties of the 

 same rock have been described by me under the same names as 

 the lavas, although I should, strictly speaking, have applied 



