182 THE BUILDING OF EASTERN AUSTRALIA 



Tertiary age. In this case, as in that of the Glass House 

 region, a monoclinal fold accompanied by extensive 

 fractures was produced in the Main Range, parallel to, 

 and in part, along the line of igneous activity after the 

 period of vulcanicity. 



The Nandewars, the Warrumbungles, and the Canoblas 

 in New South Wales, are probably also of Lower-Middle 

 Tertiary age, though the Canoblas appear rather younger 

 than the others. These mountains post-date the formation 

 a peneplain carved in the Nandewars out of Palaeozoic and 

 Trias Jura rocks, in the Warrumbungles out of the Trias 

 Jura rocks, and in the Canoblas out of the metamorphic 

 rocks and Older Volcanics. The peneplain was under- 

 going re- elevation at the time of the eruptions, for both in 

 the Nandewars and in the Warrumbungles, the volcanic 

 ejacamenta frequently infill erosion hollows in the pene- 

 plain surface. The age of this peneplain was probably 

 Ijate Cretaceous or Lower Tertiary age, like the Mole 

 peneplain ; there being no indications in these regions of 

 an older peneplain surface, the writer has always hesitated 

 to consider this peneplain the equivalent of the Stannifer 

 (Miocene). If the Avriter is right in this interpretation, 

 it follows that during the great early Tertiary elevation 

 of New England and Middle Tertiar}^ penepla nation, these 

 volcanic groups escaped wholesale degradation by being 

 situated in the Central Australian trough, which was a 

 local baselevel (probably largel}' lacustrine, as hinted by 

 abundant gypsum deposits in the west), for the erosion 

 of regions wliich participated in the Pliocene uplift. 



The fossil leaves collected in the Warrumbungle tuffs 

 by the ^\Titer are most closel}^ allied to those of the Older 

 Volcanics. 



Andrews has suggested to the writer that more or 

 less dissected peneplain underlying the volcanic pile of the 

 Warrumbungles is the equivalent of the Stannifer. This 

 view would place a post Miocene age on the volcanic rocks, 

 and assign them to the newer volcanics. Fossil evidence, 

 as well as physiographic, discountenance this view. 



The alkaline rocks of the Mittagong district, N.S.W. 

 [30], and the tinguaites of Kosiusko [31], and of Barrigan 

 [12] are probably of an early Tertiary age. 



