ALKALINE ROCKS OP S. QUEENSLAND. 251 



The analogy is veiy close between the situation of Movint Beei^wah 

 and Mount Mitchell. Mount Mitchell, on the Little Liverpool Range, 

 has the Darling Downs tableland on the west and the low Fassifem 

 plain on the east bestrewn with trachyte peaks (Mount French, Mount 

 Edwards, &c.). Mount Beerwah, on the D'Aguilar Range, has the 

 5^tanley River tableland (Woodford peneplain) on the west, and the 

 low coastal plain of Tooi-bul on the east with trachyte peaks 

 (Conowrin, Ng:iui-Ngun, &c.) towering up above it. 



The trachytes appear to have been extruded from a line of 

 fracture separating adjacent earth seginents undergoing differential 

 uj>]ift or subsidence — that is, while the one segment was uplifted the 

 adjacent one was depressed. 



3. The AijKaline Areas of Southern Queensland known to the 

 author may be divided into the following groups : — 



(a) The Maroochy-Cooran alkaline group, comprising the fol- 



lowing heights : — (1) Mount Coolum (620 ft.), consisting of 

 comendite; (2) Mount Peregian (300 ft.), pantellarite ; (3) 

 Mount Nindherry (900 ft.), pantellarite and rhyolite; (4) 

 Mount Cooroy (1,340 ft.), monzonite; (5) Mount Eerwah 

 (1,290 ft.), pantellarite and rhyolite; (6) Mount Cooran 

 (950 ft.), and Mount Cooroora (1,290 ft.), comendite and 

 riebeckite trachyte; (7) Mount Tinbeenvah, pantellarite; 

 and (8) the portion of the Blackall Range known locally 

 as The Bottle and Glass. The rhyolites of the Toolburra 

 Range and the poi'phyrites of Point Arkwright have 

 alkaline affinities. 



(b) The Glass House Group, comprising the following hills : — 



(1) Coochin Hills; (2) Mount Ngun-Ngun (810 ft.); (3) 

 Beerwah (1,760 ft.); (4) Conowrin (1,170 ft.); (5) Ban^en 

 Mountain (350 ft.); (6) Tibrogargan (1,160 ft.); (7) Ewin; 

 (8) Beerburrum (920 ft.); (9) Tunbubudla (1,020 ft.); (10) 

 Micketeebumulgrai (750 ft.), &c. All these mountains 

 consist of arfvedsonite, riebeckite, and eegirine comendites, 

 and trachytes. 



(c) The Mount Flinders Group, consisting of Mount Flinders 



and a number of smaller mountains and hills surrounding 

 the larger heights. Mount Flinders (2,240 ft.) is composed 

 of alkaline felspar porphyry, tegirine trachyte, tuffs, and 

 breccias, and dacitic lava. The smaller hills consist mainly 

 of pantellarite and breccias. 

 {d) The Little Liverpool Range Group. — This consists of 

 most of the peaks on the Little Liverpool Range 

 (Mount Mitchell, Mount Huntley (4,153 ft.), Spicer's 

 Peak, Mount Roberts (4,850 ft.), and Wilson's Peak); 

 several parts of the Macpherson Range, and a number 

 of isolated peaks in the Fassifern plain ; including Mount 

 Flinders (2,240 ft.), comendite; Mount Edwards, quartz 

 trachyte; Mount Greville, quartz trachyte; and many 

 others. Mount Obelisk and a number of other peaks on 

 the New South Wales side of the border form a continua- 

 tion of the Little Liverpool Range, and consist of 

 riebeckite comendite. 



