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THE GEOLOGY AND PETROLOGY OF THE GREAT 

 SERPENTINE BELT OF NEW SOUTH WALES. 



Part iii. Petrology. 



By W. N. Benson, B.A., B.Sc. 



(Plates xxv.-xxvii.) 



Before commencing the detail of this chapter, I wish to record 

 my indebtedness to many friends, for advice and assistance in this 

 portion of the work. Professor Bonney has given me constant 

 help, placing his unrivalled knowledge and collections of ultra- 

 basic rocks at my disposal. Mr. Harker has rendered every assist- 

 ance possible in checking petrological determinations, and direct- 

 ing me to the broader aspects of the work, and the most useful 

 literature. Mr. Hutchinson has guided me through analytical dif- 

 ficulties, and has given every facility for working in the Mineralo- 

 gical Laboratory at Cambridge. To the guidance of Dr. Flett in 

 the Lizard area, and of Mr. Dewey in North Cornwall, I am 

 indebted for field-knowledge of English serpentines and spilitic 

 rocks ; while, by permission of the Director of the British Geologi- 

 cal Survey, and the Petrologist, Mr. H. H. Thomas, I have been 

 able to examine the official collections of slices of these rocks 

 Many useful facts, also, were gleaned from a study of the collec- 

 tions of the University of Paris, to which I was given access by 

 Professor Lacroix. To all these gentlemen, I offer most hearty 

 thanks. 



The following chapter is based upon a collection of about 900 

 specimens, and over 320 microscopical slides of rocks gathered 

 from all parts of the area. These are very varied in character, and 

 must be described under many heads. The igneous rocks are 

 treated in the first portion of this chapter; the breccias, agglomer- 

 ates, tuffs, and normal sedimentary rocks in the second portion. 



