158 THE GEOLOGY OP THE CANOBOLAS MOUNTAINS, 



this Society,* in which he referred particularly to the occurrence 

 of andesitic lavas on this mountain. In 1891, the Rev. J. M. 

 Curran, in a paper read before the Royal Society of New South 

 Wales,! described several rocks from this area, including porphy- 

 ritic basalts from German's Hill, and fine-grained basalts from 

 the Orange Racecourse. The German's Hill rocks were evidently 

 andesites. 



In December, 1901, one of us (C. A. Siissmilch) began a 

 geological survey of the area in conjunction with the Rev. J. M. 

 Curran. A considerable amount of field-work was then done, 

 but the work was subsequently dropped. A re examination, some 

 years later, of the material which had been collected, together 

 with subsequent visits to the Canobolas by one of us (C.A.S.) 

 showed that a resurve}'' was desirable. This has now been done, 

 and although the rough geological map which resulted from the 

 previous investigation forms the basis of the present survey, the 

 field-work has been done practically de novo. 



ii. PfiTROGRAPHY. 



The rocks of this area may be classified as follows : — 

 I 1. Diatomaceous earth. 

 ,„ J 2. Tuffs. 



I 3. Lavas — Comendites, Trachytes, Andesites, and 

 I Basalt. 



4.(?)Carboniferous — Augile-Porphyrite (intrusive). 

 5. Devonian — Shales, Sandstones, Quartzites and 

 _, , Conglomerates. 



PaL.EOZOIC. ^ ^ c^., . ^, , -r . . -nx ^' 1 



b. Silurian — Slates, Limestones, Khyolite, and 

 i Rhyolite Tuff. 



[ 7. Ordovician — Graptolite Slates. 

 Ordovician. — Graptolite slates occur over a small area near 

 Cadia, a few miles to the south of the Canobolas. This area has 

 not been included in the accompanying map. 



* Note on the " Occurrence of Andesitic Lavas at the Canoblas, near 

 Orange." These Proceedings, Second Series, Vol. v., p. 426, 1890. 



t A Contribution to the Microscopic Structure of some Australian Rocks. 

 Journ. Proc. Royal Soc. of New South Wales, Vol. xxv., pp. 198-204, 1891. 



