446 H. S. JEVONS, H. I. JENSEN, T. G. TAYLOR AND C. A. 8USSMILCH. 



11. Characters of the Secondary Minerals. 



12. Origin of the Analcite. 



13. Consideration of the Analyses. 



(Analyses stated in full here, only the more important 

 constituents having been stated under the descrip- 

 tion of rocks.) 



14. Nomenclature of the Rocks, (1) on the old, and (2) on the 



American quantitative systems. 



15. Variations of Composition in the main mass. Distribu- 



tion of minerals and space relations of the resulting 

 rocks. 



(Tables showing mineral composition of typical 

 specimens.) 



16. Metamorphism and assimilation of the country rock. 



Fart III. Segregation Veins. 



By C. A. Sussmilch and H. Stanley Jevons. 



17. Distribution of the Segregation Veins in the mass. 



18. Megascopic characters and relations of the rocks compos- 



ing the veins. 



19. Micrographic description of the pegmatites and aplites. 



Appendices. 



I. Determination of the mode. 

 II. Restoration of the original mineral composition. 



I. General Geology and Shape of the Mass. 



By T. Griffith Taylor and H. Stanley Jevons. 



1. Introduction. 

 In the midst of a gently undulating well wooded country, 

 composed of Triassic (Wianamatta) shales, and almost at 

 the centre of the great Permo-Oarboniferous and Triassic 

 basin of New South Wales, there occurs a massive intrusion 

 of essexite (or dolerite) which displays many features of 

 extreme interest, and which has been so well exposed by 

 quarrying operations that it seems to merit a detailed 

 description. The mass forms a conspicuous elevation — 



