ALDABRA ISLANDS, in the Indian ocean, part of the Brit ish colony of Seychelles, in 9° ,30' S., 46° E., 265m. N.W. of the northern point of Madagascar and 69om. S.W. of Mahe, in the Seychelles. The islands are an oval atoll some 4om. in circumfer ence and about broad, enclosing a shallow lagoon. Channels divide the ring into four islands, which rise from 2o to 8oft. above the sea. Grande Terre.or South island forms three-fifths of the circumference. The other islands are West island or Ile Picard, Polymnie, Middle island, and several islets (e.g., Ile Michel) in the lagoon. The total land area is estimated at about 6osq.m. Pop. (1906) 127. The external cliffs of coral and lime stone are in places replaced by sandy beaches and sandhills. There is very little soil. Dense scrub covers most of the land, but the lagoon shore is bounded by mangrove swamps. The flora and fauna are of great interest. The gigantic land tortoise (Testudo elephantina) is now carefully preserved. Peculiar birds include a rail (Dryolimnas aldabranus), an ibis (Ibis abbottii) and a dove (Alectroenas sganzini). Oysters and large crabs occur, and a small mussel is found in enormous numbers. The flora includes man groves, Rubiaceae, Sapotaceae and other forms requiring more than pure coralline material for their growth. The predominant species are Madagascar plants and birds, carried by currents and winds. There are few endemic species of plants. Aldabra seems to have been built up on the sunken surface of the old Gondwana continent by a deposit, in the opinion of Prof. A. Voeltzkow, of foraminiferal remains (mostly coccoliths and rhabdoliths), and it has never been joined to any other land (Stanley Gardiner). Dupont states that at Aldabra the coral foundation is totally above water. The coral limestone of the atoll is vitrified and gives out a ringing sound when struck or simply walked on. The coral is generally reddish, but runs from light yellow to chocolate-brown.
Aldabra was visited by the Portuguese in 151i but was already known to the Arabs, who gave the name. In the i8th century the islets became dependencies of the French establishments at Bour bon (Reunion). In 1810 with Mauritius, Bourbon (for a time), the Seychelles and other islands, Aldabra became British. The in habitants are emigrants from the Seychelles. Goats are bred and coco-nuts cultivated, but fishing is the chief industry. With other outlying islands Aldabra is held under lease from the Seychelles Government, the lessees having exclusive trading privileges.
See R. Dupont, Report on a Visit of Investigation to . . . the Aldabra Group of the Seychelles Islands (Seychelles, 19o7) ; Dr. Abbott in Proceedings, United States National Museum (Washington, 1894) ; A. Voeltzkow in Abh. der Senckenbergischen Naturforschenden Ges. vol. xxvi. pt. iv. (pgoi) ; J. S. Gardiner, "The Indian Ocean," Geo. Journ. (Oct. 1906).