THE 



VOYAGE OF H.M.S. CHALLENGEE. 



REPORT on the PETROLOGY of the ROCKS of ST. PAUL (Atlantic). 

 By the Rev. A. RENARD, F.G.S., F.R.M.S., &c. 



THE object of the present Keport is to give a lithological description of the specimens 

 collected on the island during the voyage of the Challenger. Numerous and carefully- 

 selected specimens of these rocks were forwarded to me from the Challenger Office for the 

 purpose of minute petrographical investigation and description. They were accompanied 

 by a complete series of microscopical sections prepared by Mr. Murray. I received at 

 the same time the chemical analyses of the principal specimens which had been made 

 by Professor Brazier, of Aberdeen, at the request of Sir Wyville Thomson. These 

 analyses have been inserted in the text of the report. 1 



The description of this rock-mass, standing as it does apart in the mid- Atlantic, is in 

 every way worthy the attention of geologists. The position of this islet, far removed from 

 any continent, lost as it were in the middle of the ocean, caused it to be considered as the 

 last trace of some vast districts lost by submergence. In the hypothesis of an Atlantis 

 the island of St. Paul is one of the peaks belonging to the continental masses that formerly 

 existed between the Old "World and the New, and which united those islands now 

 separated by the ocean, but which certain relations in their fauna and flora have led some 

 naturalists to consider as at one time united. With this revival of the idea entertained in 

 ancient times by the Greeks and the Phoenicians regarding the Atlantis, it was admitted, 

 on the ground of the distribution of living beings, that there formerly existed north of 

 the Equator a continental mass, of which the present groups of islands scattered through- 



1 After completing this report I wished further to prove some of the conclusions at which I had arrived, by making 

 a fresh analysis on a specimen which I had used in my studies. My friend Dr. L. Sipocz kindly undertook to do this 

 for me, and the result of his investigations will be found ia the present work. The analyses of Prof. Brazier are indi- 

 cated by (B) in the text 



A 



