THE 



VOYAGE OF H.M.S. CHALLENGER. 



PHYSICS AND CHEMISTRY. 



REPORT on the Rock Specimens collected on Oceanic Islands during 

 the Voyage of H.M.S. Challenger, during the years 1873-1876. By 

 Professor A. Renard, LL.D., Ph.D., F.G.S., Hon. F.R.S.E., etc., of the 

 University of Ghent, Belgium. 



PREFACE. 



The examination of the rocks which are described in this Report was commenced at 

 the time when I became associated with Mr. Murray in the study of the deep-sea 

 deposits collected during the cruise of the Challenger. Mr. Murray had discovered 

 that loose volcanic materials played a very large part in the formation of the deposits 

 of the deep sea, and it was considered desirable to institute a comparison between these 

 and the products of the same origin in volcanic islands situated in, or on the borders 

 of, the great ocean basins. These researches have been conducted with the object just 

 indicated, and have led to a detailed description of the rocks placed in my hands. As 

 this description has no direct relation to that of the deep-sea deposits, the Editor has 

 judged it desirable to publish these researches in a separate Report, comprising 

 especially questions relative to the lithology and mineralogy of the hand specimens 

 collected on Oceanic Islands during the cruise of the Challenger. 



All considerations of a more general order, as to the relations which these islands 

 bear to the orography of the deep sea, will be treated of in the Report on the Deep-Sea 

 Deposits. 



I desire to thank here Mr. John Murray, Mr. J. Y. Buchanan, Professor H. N. 

 Moseley, and Fleet Surgeon George Maclean, R.N., for all the information they have 

 been so kind as to furnish concerning the rocks collected, and for placing their numerous 

 specimens at my disposal. 



(PHYS. CHEM. CHALL. EXP. PART VII. 1889.) « 



