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THE DISTRIBUTION, ORIGIN AND RELATIONSHIPS 

 OF ALKALINE ROCKS, 



By H. I, Jensen, D.Sc, late Linnean Macleay Fellow of the 

 Society in Geology. 



Ch.i. Introduction. 



This paper is in the main a revision of a portion of a thesis 

 submitted to the Sydney University with the view of qualifying 

 for the Doctor of Science degree. The work on which the thesis 

 is based was carried out while I held the position of Linnean 

 Macleay Fellow of the Society. I am indebted to the University 

 authorities for permission to republish. 



To my teachers, Professor T. W. Edgeworth David, B.A., 

 F.R,S., and Mr. H. Stanley Jevons, M.A., B.Sc, F.G.S., I owe a 

 lasting debt of gratitude for the excellence of the instruction 

 which they have imparted to me. To the former, in particular, 

 I am indebted for my acquaintance with the broad principles of 

 structural geology and for the constant interest which he has 

 taken in my own work; to the latter I feel grateful for thorough 

 instruction in petrology and for an introduction to the German 

 masters of penological science, for whom my esteem has in nowise 

 been lessened by a closer acquaintance with the American 

 authorities. 



In my researches I have given particular attention to alkaline 

 rocks, partly because since boyhood my interest had been attracted 

 by the wonderful monoliths of the Glass House Mountains near 

 my home at Caboolture, Queensland, partly because alkaline rocks 

 have been investigated in great detail in other parts of the world, 

 while in Australia, a continent marvellously rich in alkaline 

 comagmatic regions, they have been almost totally neglected. On 

 closer acquaintance, I soon found that alkaline rocks, in addition 

 to having an interest for their own sake, might shed important 



