514 GREAT SERPENTINE BELT OF NEW SOUTH WALES, i., 



Permo-Carboniferous Beds so long escaped notice. There was so 

 little to distinguish them from the older palaeozoic slates asso- 

 ciated with them. No doubt, the series of Permian and early Meso- 

 zoic intrusions accompanied these foldings. 



A long period of erosion followed, and the granite was laid 

 bare. On it was deposited a series of arkoses, conglomerates, and 

 sandstones, which occur in the neighbourhood of Warialda, over- 

 lying granite ; rocks of the Eastern series, serpentine and Barraba 

 mudstones. These sandstones, etc., are about 100 feet thick, and 

 contain Alethopteris, Phyllopteris, and Brachyphyllvm, and have 

 been referred to the Jurassic period(6d). They are quite undis- 

 turbed or merely gently inclined. In the neighbourhood of 

 Slaughterhouse Creek, they form the upper parts of the range, 

 capped by basalt, and are probably rather thicker than at 

 Warialda. 



The Tertiary formations are largely volcanic, and, for the sake 

 of completeness, a very brief resume* of Dr. Jensen's(9) work in 

 the Nandewar district, together with other facts, may here be 

 given. In early Tertiary or late Mesozoic times, there occurred 

 crustal movements, throwing down the western part of the Nande- 

 war region. This induced volcanic action, commencing with the 

 intrusion of dolerite-sills into the Permo-Carboniferous strata, fol- 

 lowed by: — 



(a) Sill-like and laccolitic intrusions of syenite, accompanied by 

 flows of phonolite, trachyte, and allied alkaline lavas. 



( b ) Alkaline andesites and more porphyry-sills. 



(c) Basic porphyrite-dykes and basalt-flows, which lasted into 

 Pliocene times. 



In the Barraba region, an ancient, wide-spreading river-basin 

 became greatly alluviated during the early part of these eruptions, 

 and a considerable amount of trachytic tuff is contained in its leaf- 

 bearing clays, which are of considerable thickness, and contain 

 Eucalyptus; the upper layers include a bed of diatomaceous earth 

 about 10 feet thick (22). These are covered by the great flows of 

 basalt of the last igneous epoch. Elsewhere there are masses of 

 basalt covering a greater or less thickness of leaf -bearing, Tertiary 



