406 Ridley — Raised Reefs of Fernando de Noronha. 



Art. XLYIII. — The Raised Reefs of Fernando de JVoronha; 

 by Henry K Ridley, M.A.J F.L.S., Director of Gardens 

 and Forests, Straits Settlements. 



I have recently received three numbers of this Journal (for 

 February, March and April, 1889) in which are papers by 

 Messrs. Branner and Williams on the Petrology and Mineral- 

 ogy of Fernando de Xoronha. I was one of the party sent 

 out by the Royal Society of England and the British Museum, 

 to explore this island not only mineralogically but botanically 

 and zoologically in 1887. My companions were the Rev. T. S. 

 Lea and Mr. G-. Ramage. We explored the whole group and 

 brought home upwards of 200 specimens of rocks and min- 

 erals, with sketches, plans and photographs of the more inter- 

 esting geological bits. The minerals, which are now in the 

 British Museum, were worked out by Mr. Davies of that 

 establishment, and a short account was published in the Jour- 

 nal of the Linnean Society (Botanical Division) as an intro- 

 duction to the natural history. These are, though much 

 condensed as the Linnean Society does not as a rule publish 

 petrographical papers, our views upon the structure and his- 

 tory of Fernando de Noronha, from its petrology. I hope 

 Mr. Davies will publish further notes upon our rock-specimens, 

 at fuller length. The results we arrived at as to the origin 

 and history of the island differ a good deal from those of 

 Messrs. Branner and Williams especially as to the relations of 

 the phonolite and basalt and the rocks included by the latter 

 under the name of £eolian sandstones. It is about the latter I 

 should like to speak as we carefully examined this rock in all 

 parts of the islands and brought home specimens in all states 

 of existence. 



Briefly stated our theory was that, this certainly rather 

 variable rock, is what we have called reef rock, and is the same 

 rock that is forming at different spots along the shores of Fer- 

 nando de JSToronha, of the Recife at Pernambuco and at Itama- 

 raca in the same province. 



This reef rock is full of corals, nullipores, broken shells, 

 tests of echini, and at low water mark it is full of living 

 organisms. Break into the interior it is more and more com- 

 pact the nearer you go towards the shore, and eventually and 

 at no great distance within the mass, you will see that the 

 forms of its constituent animals are gone, and the whole is an 

 amorphous mass of carbonate of lime, not as I shall show later, 

 pure but mixed with mud in varying quantities. Owing to its 

 irregular structure and growth it is soon worn into those 

 curious shaped pinnacles and peaks that one sees often buried 



