BY fl. I. JENSEN. 569 



feet. At Tooraweanab, to the S.W. of the mountains, it is aVjoiit 

 1,500 feet; and at Tundebrine about 1,400 feet. At Tenandra 

 Station it has fallen to about 1,100 feet; at Goorianawa Station 

 the level is 1,200 feet; at Bngaldi it is about 1,350. Mundooran 

 is about 1,000 feet above sea-level, Gumin-Gumin about 1,200, 

 and Kalga 900 feet. 



We see then that there is a tendency for the level to drop 

 rapidly to that of the western plains around, i.e., to about 900- 

 1,100 feet. Around Coonabarabran there is a tableland elevated 

 400-500 feet above the Liverpool Plains to the S.E. Studded 

 over this tableland are flat-topped sandstone mesas, and butte.s 

 of trachyte; the former all reach a level of between 1,900 and 

 2,000 feet — the same height as the Warrumbungle Range where 

 it is composed of sandstone. The trachytic buttes, e.g., Nandi, 

 The Forked Mountain, Yarrighnan, Yarabala, etc., usually attain 

 the same altitude, but frequently vary within wider limits. 

 Very often trachyte caps a sandstone mesa, thereby increasing 

 its altitude. The buttes and cappings represent remains of a 

 sheet of lava which tilled the valleys in the sandstone in the 

 volcanic period. The lavas in the Warrumbungle Mountains 

 proper overlie a continuation of this Coonabarabran plateau. 



The foregoing description of the Warrumbungle Mountain 

 topography with a glance at the reproduction of a stereogram 

 (Plate XXV.) shows that the region has the nature of a lava cono- 

 plain, as pointed out in my preliminary note. 



South and west of the mountain group we also find mesas and 

 buttes which were originally portions of the Warrumbungle 

 conoplain, but are now severed by erosion. Thus between Toora- 

 weanab and Bearbung there are the Dillys, masses of sandstone 

 with steep, often vertical walls, which overlie conglomerates 

 (probably Permo-Carboniferous), and are in some cases capped 

 with trachyandesite at a level of 2,000 feet. Similar masses 

 occur north of the Warrumbungles in the Pilliga Scrub. 



The soils are very different in different parts. In the sand- 

 stone belts they are poor and sandy, and characterised by pine 

 {Callitris rohusta and C. calcarata) and white gum {Eucali/ptus 



