560 THE GEOLOGY OF THE WARRUMBUNGLE MOUNTAINS, 



formations. Naturally in the centre of the volcanic region dips 

 are much disturbed. West of the Warrumbungles we find, at 

 Tenandra, calcareous shales dipping W. at 10° — probably of 

 Upper Trias- Jura or Cretaceous age. These too are intruded 

 by andesitic eruptives (Tenandra Mountain) coeval with the 

 Warrumbungle lavas. 



At Scabby Rock, about 10 miles north of Coonabarabran, we 

 find the trachytic knob surrounded by a narrow rim of highly 

 inclined slates with quartz reefs, surrounding which we find 

 gently inclined Triassic (or Permo -Carboniferous) sandstones. 

 The slaty rocks are probably of Gympie (Carboniferous) age. 

 (Figs. 4a and b). 



At Timor Rock, about 8 miles west of Coonabarabran, fragments 

 of chert are included in the trachyte. Several fine specimens of 

 chert with Glossopteris (Permo-Carboniferous) were collected by 

 Mr. McLeod, until lately schoolmaster at Bugaldi, near Wheoh 

 Mountain on Upper Bugaldi Creek. I have been unable to find 

 the outcrop, which is probably small, and brought to the surface 

 by an igneous intrusion. 



These occurrences, however, prove that rocks older than the 

 Triassic occur at no great depth. One might also mention in 

 this connection that at Tundebrine Station pieces of quartz and 

 fragments of biotite granite have been brought to the surface by 

 volcanic action. 



The Pyrodastic Rocks consist of tuffs and breccias. Inter- 

 bedded with them occur diatomaceous earths at Bugaldi, Yarra- 

 man, Wandiallabah Creek and Govvang. Tuffs and breccias of 

 the arfvedsonite trachyte-comendite series were met Avith at 

 Gowang, Wandiallabah Creek, Berum Buckle (Tannabar), Timor, 

 Scabby Rock and Siding Spring Mountain. They occur very 

 abundantly everywhere in the heart of the AVarrumbungle 

 Mountain group in association with the trachytes related to 

 them. Andesitic and basic tuffs occur in association with more 

 basic lavas on top of Mount Exmouth, at Chalk Mouiitain, Cow 

 Mountain, Lion's Head, Paddy McCulloch's Mountain, and other 



