On the Geology of Flat and Gahnel Inlands hy 

 Ph. B. Ap-es, M.-D., London. 



In a volcanic island of recent geological formation 

 and small extent, little more than the evidences of vol- 

 canic action, and the usual mineral products of that 

 action, can be expected to interest the geologist. Mau- 

 ritius and the small islands to the north of it, being 

 of recent geological formation, I Avas agreably sur- 

 prized by finding on one of the neighbouring islands a 

 formation of mvich geological interest as evidencing the 

 existence at a former period of a far larger tract of 

 land in these seas ; mutations of level of the islands 

 themselves, together with the remains of a fossil flora, 

 interspersed with fossolised specimens of still existing 

 shells and corals. 



The group of islands to the north of Mauritius are 

 Gunner's Quoin, Flat Island, Gabriel Island, Round 

 Island and Serpent Island, the nearest of which Gun- 

 ner's Quoin is about three miles from the main-land, 

 while the furthest. Serpent Island, is about twenty-five 

 miles. The first of these. Gunner's Quoin is a mass of 

 volcanic rocks, apparently destitute of any secondary 

 formation, the sea around it being generally so rough, 

 as to preclude the formation of a coral reef. Round 

 Island has, from the descriptions of those who have vi- 

 sited it, a similar formation, being a hemispherical 

 mass of volcanic rock, the surface of which is worn 

 into fantastic figures by the action of air and Avater. Of 

 the geological character of Serpent Island, I have been 

 able to gain no information, but its Avhite appearance in 

 the distance, contrasted with that of the other islands, 

 would seem to indicate either a different formation, or 

 that the volcanic rock is covered by some secondary 

 deposit. 



During a residence of several months on Flat Island 

 as Superintendant of Quarantine, I had ample leizure 

 and opportunity for the examination of the geological 

 foniKilion of Fiat and Gabriel Islands, the results of 

 which, as they proved interesting to myself, may bo 

 thought worthy of the attention of the Royal Society. 



Like Mauritius, these islands are of volcanic origin. 



