1911 Encyclopædia Britannica/St Paul (island)

From Wikisource
Jump to navigation Jump to search

ST PAUL, a volcanic island in the southern Indian Ocean, in 38° 42′ 50″ S., 77° 32′ 29″ E., 60 m. S. of Amsterdam Island, belonging to France. The two islands belong to two separate eruptive areas characterized by quite different products; and the comparative bareness of St Paul contrasts with the dense vegetation of Amsterdam. On the north-east of St Paul, which has an area of 23/4 sq. m., is a land-locked bay, representing the old crater, with its rim broken down on one side by the sea. The highest ridge of the island is not more than 820 ft. above the sea. On the south-west side the coasts are inaccessible. According to Vélain, the island originally rose above the ocean as a mass of rhyolitic trachyte similar to that which still forms the Nine Pin rock to the north of the entrance to the crater. Next followed a period of activity in which basic rocks were produced by submarine eruptions—lavas and scoriae of anorthitic character, palagonitic tuffs, and basaltic ashes; and finally from the crater, which must have been a vast lake of fire like those in the Sandwich Islands, poured forth quiet streams of basaltic lavas which are seen dipping from the centre of the island towards the cliffs at angles of 20° to 30°. The only remaining indications of volcanic activity are the warm springs and emanations of carbon dioxide.

See C. Vélain, Passage de Vénus sur le soleil (9 décembre 1874). Expédition française aux Îles St Paul et Amsterdam (Paris, 1877); Description géologique de la presqu’île d’Aden . . . Réunion . . . St Paul et Amsterdam (Paris, 1878); and an article in Annales de géographie, 1893.